PSTX Seal

Emerging Infections and Biodefense

Dr. Lemon: Thank you very much, Jack. It's a pleasure to be here this afternoon. I'm just happy that the game is not closer or there might be fewer of you. It's good to see Texas doing so well.

I'm going to be talking this afternoon with two of my good friends and colleagues here in the infectious disease faculty, Scott Weaver and John Peterson, about emerging infectious diseases. I think to some extent emerging infectious diseases is a bit like a football game. Right now the score is - maybe the humans are little bit ahead of the bugs. But it's not clear what the end game is going to be. And it's a continuing struggle.

What I want to present today is, my part first, an overview of why infectious disease are important, what we mean by "emerging infectious disease" - throw out a few specific examples of that - and then describe some of the activities that are taking place here at UTMB to address those issues. I plan to focus more specifically on the question of highly pathogenic avian (or H5N1) influenza that has been in the press so much lately, and to update you on the current situation in Asia, describe some of the challenges that this poses for public health officials worldwide, and then wrap up with a specific plan ‑‑ a proposal that we are developing in collaboration with some of our partners here in Texas, for improved flu surveillance in Texas.

Now, my message today will be that the threat of infectious diseases is much more broader than what we usually conjure up when we think of "biodefense". When we think of biodefense we think of bioterrorism ‑ for example, the anthrax attacks of 2001. Those were very important signal events that we need to pay a great deal of attention to because it's very clear that when something like that happens once, someone will try it again sometime in the future. On the other hand, I think that most of us who work in infectious diseases believe that Mother Nature is the mother of all terrorists, and that that's what we really need to be concerned about.

But in truth these two threats, bioterrorism and the natural emergence of a new infectious disease, go hand in hand. So that is what I will talk about first in this overview. Then I'll be followed by Scott Weaver who will discuss in greater detail a virus that has threatened Texas in the past and may in the future - a naturally emerging virus, but one that also has a bioterrorism side to it potentially. And then Johnny Peterson will talk about anthrax and what we're doing here at UTMB to look at better ways to treat persons who might become infected with this bacterium.

So by way of starting out, I think all of you are aware of the fact that infectious diseases seem to be much more important today than they were perhaps 30 years ago. In fact, back a few decades ago, the Surgeon General of the United States made a statement to the effect that infectious diseases were licked. We had penicillin, we had antibiotics, and infectious diseases were on the run.

Well, since then we have eradicated smallpox and we have really knocked down polio. But polio is threatening to come back. Equally important, many new infections have seemed to emerge out of nowhere ‑ diseases we knew nothing about before, diseases like AIDS or hepatitis C, for example, or Monkeypox and West Nile Virus infections here in the United States, where they never occurred before.

At the same time the antibiotics that we use to treat bacterial infections are becoming less and less active against the common important pathogens that we see in our hospitals every day. The problem of antimicrobial resistance is becoming very serious indeed.

Now, the factors that drive the emergence of new infections - for example the appearance of West Nile or Monkeypox viruses in the United States ‑ are multiple. The overarching factors are shown on this slide: the deforestation of rain forests; social factors leading to migration from rural regions to cities internationally, resulting in the rise of "mega-cities" of 20 million persons, many of whom have no access to clean water or any form of preventive health care; global air travel, with potentially rapid transport of persons and pathogens internationally; the creation of new environments that favor the breeding of insects, important disease vectors for many pathogens; and finally, viral and bacterial evolution.

Most of these factors reflect the huge growth in the number of humans populating this planet; how we now occupy virtually every corner of this planet and what we have done to the environment and as we have changed the environment that we lived in, how animals, insects, bacteria, and the viruses have responded, in many cases changing the way that we can come in contact with as we have done so.

Keep in mind that a bacteria or a virus requires only a few minutes or even seconds to replicate one generation to the next. A human takes 25 to 30 years in today's society. So viruses and bacteria have the ability to change their genetic makeup much more rapidly than we do. They can out-evolve us very easily. They can more readily adapt to new environments, new situations and new opportunities for their own survival.

And the outcome of all this is shown on this slide: a really large number of infectious diseases, many of which you will recognize, like H5N1 influenza or hepatitis C or Lyme disease, that are all new infections that weren't in the textbook when I went to medical school, which wasn't all that long ago. But there's others here that you will recognize like yellow fever and dengue, cholera ‑ old infections that have historically threatened humans, but that are now re-emerging in certain areas of the world, or in some cases invading new territory.

And then on top of this map we have anthrax, the bioterrorist event here in the United States. Now, that's only one example, only one example in the United States even, where bacteria have been used purposefully to cause illness or potentially death, used with intent to do serious harm.

In this integrative view, we can really consider bioterrorism, or the human dissemination of a pathogenic agent, as simply another factor driving infectious disease emergence. Like many of the others, it is a factor driven by variety of socioeconomic, political, demographic issues.

Now, a seminal report came out of the Institute of Medicine in the early 1990s point out the danger that emerging infectious diseases pose. This was co-authored by Josh Lederberg, a Nobel Laureate, and Bob Shope, who was a member of the faculty at UTMB up to his death just a little over a year ago. That report was followed by a more recent report, "The Microbial Threats to Human Health" Committee report, which summarized their findings by concluding that a "transcendent moment nears upon the world for a perfect microbial storm", sort of like Sebastian Junger's report of the perfect meteorological storm.

This storm is coming about due to a convergence of factors that include changes in our physical environment, changes in the society we live in, the political and economic forces that drive human behavior, changes in ecology, the evolution of microbes and viruses and their interface with humans, and a variety of genetic and biological factors that we don't understand completely today.

Now, the outcome of all this is the advent of an infection like SARS. A disease caused by a coronavirus. Prior to its appearance in 2003 the textbooks would all tell you that coronaviruses don't cause serious pulmonary disease in humans. Now we know they do. In this outbreak, which had its origin through some interaction between humans and animals that we don't still understand completely, this coronavirus infected about 8,000 people and caused about 800 deaths worldwide.

The single most striking feature of this outbreak was the speed with which it spread; from China to Hong Kong to Toronto and that speed was facilitated by commercial air traffic, and the fact that you can now move from any point on earth to any other point in less than 24 hours. A hundred years ago that same movement would have taken weeks, if not months. So that speed of movement, coupled with a much greater number of people now populating the planet, pose great challenges, and create new interfaces between people and animals, opening up opportunities for pathogens to jump from one species of animals to another (i.e., humans). I think Dr. Weaver may talk more about this.

So SARS is one example: it popped up, it was controlled, and now it's gone away. Is it going to come back? We really don't know. It's a continuing possibility, however. I've already alluded to Monkey pox in the U.S. This was imported from Africa to the United States in Gambian giant rats that were brought into the United States as pets ‑ a rather surprising fact. In pet stores, these giant rats infected prairie dogs, which also were to be sold as pets. And several pet owners, including some children, became infected, in all about 72 cases.

The monkeypox agent is a virus that's distantly related to smallpox. It belongs to the same family of viruses, but it causes a much less serious infection in humans. And in this case there were no deaths, but still a great potential for serious disease.

West Nile I think you're all aware of. It's changed our behavior. We don't sit outside in the evening any more unless we're enclosed in a screened porch, hopefully, to avoid mosquitoes. This is a virus that was unknown in the United States prior to 1999 when it suddenly appeared in bird populations near JFK Airport. Then, very predictably, over a succession of years, it expanded from that point in the northeastern United States westward until at this point every state in the country has experienced the virus. Last year, this past year, has been a relatively mild year for West Nile compared to what it was a few years ago. But we've had a total of 2,744 cases as of this week in the U.S. In Texas, 158 cases and ten deaths. So this is a very real continuing problem.

Prion disease or "mad cow" disease ‑‑ you're all probably aware of the recent identification of several infected cattle in the United States. The magnitude of that problem and what that means for the cattle industry and human safety is something that's extremely important, yet not yet clear. You're all aware of what's happened in the U.K. in the late '80s and '90s where the mad cow outbreak among cattle led to a number of human cases and deaths associated with the mad cow outbreak in the U.K.

It's very interesting if you look at all of these emerging infectious diseases, as Dr. Julie Gerberding, currently director of the Center for Disease Control and Prevention (a.k.a., the "CDC") in Atlanta, has pointed out here, almost all of them have their origins in the interface between animals and humans. That is, they are mostly all "zoonotic infections". And from a policy perspective, one of the places where we fall down repeatedly in the U.S., and in virtually every other country in the West, I think, is in properly integrating agricultural (animal) health and human health control measures at all levels or the government and, indeed, even in professional schools!

In the United States we have the U.S. Public Health Service (the CDC monitoring public health and the NIH managing research) concerned with maintaining human health. On the other hand, we have the USDA taking care of animals. They don't talk with each other or work together nearly as much as they should. I think they're doing a much better job of it now for reasons that Dr. Gerberding's put on the slide here, but there's still room for a lot of improvement there I think. And, again, I think you'll hear more about this this afternoon.

There are also viruses that can't be transmitted to humans from animals, and that pose threats only to our herd animals. Foot and Mouth Disease Virus (FMDV) is the most worrisome of these. This is a virus that was present in Texas several generations ago, but it has not been seen in this state for over 60 years, I believe. It's not been found in the United States for that period of time. However, the U.K., which was previously free of this infection, sustained a large and rapidly expanding outbreak in 2001, as you can see here. This outbreak was recognized rapidly, but by the time it was recognized, infected sheep had been shipped all over the country because of the large scale movement of animals within the sheep industry.

Within a matter of weeks, almost 4 million animals were slaughtered in the U.K. in an effort to bring that outbreak under control. The economic consequences for the U.K. were really disastrous, not only to the industry most directly involved. Walks in the countryside were banned in an effort to limit spread of this highly contagious virus, and the tourism industry was strongly affected. In fact, a survey by a government ministry in 2002, looking at six mainly rural districts, found that about a third of all businesses had been affected. As you can see here, about a fifth of those businesses were "very severely" or "devastatingly" affected by the outbreak.

This outbreak was brought under control by the slaughter of animals, previously the tried and proven way to stop an outbreak of FMDV. Our policy here in the United States today is that if a case is identified, the affected herd is slaughtered. There's no magic drug, no vaccine that we can use in today's setting to effectively control an outbreak. Now, in fact, there are good FMDV vaccines, but the reason that vaccines aren't used to prevent the infection is one of economics. It’s currently impossible to distinguish an infected from a vaccinated animal by testing of blood, and the import or export of FMDV-infected meat is forbidden by the laws of many countries. Thus, it is the lack of willingness of any country to import meat or cattle products from a country in which FMDV infection is suspected in cattle or sheep. This would be the case if you used the vaccine to control an outbreak today. However, modern science should be able to find a way around this, and more research on this is needed quite urgently.

And then, finally, bioterrorism, another facet of infectious disease emergence, due to purposeful, malevolent, human-mediated dissemination of pathogens. You'll be hearing more about this from Dr. Peterson.

So, as Dr. Stobo was saying at the outset, when the anthrax attack happened in 2001 we believed ‑ we felt very strongly - that we here at UTMB could contribute in a significant way to the national response to the concerns raised by bioterrorism, which were great, as you know, in the wake of the 2001 9/11 events. Prior to that period of time we had, been developing a program that focused on natural mechanisms driving the emergence of infectious diseases. You'll hear more about this from Scott Weaver shortly. The Center for Tropical Diseases was started here at UTMB under Dr. David Walker's direction in 1994, and had achieved the capability to work with viruses in ways in which interactions between insect vectors, animals, and humans, the integrated ecology of infectious diseases, was taken into account and could be further elucidated.

I think if you go to most universities where there are excellent microbiology departments and virology research programs, you'll find them focusing mostly on molecular virology, something which my own research group which works on hepatitis C tends to do. In contrast, here on the UTMB campus, we have a large number of scientists who are very much aware of, knowledgeable about, and able to work on the interaction between viruses, humans, insects, and animals. That's the continuum from which these emerging infections evolve, and it just so happens that most of the agents that we worry about in the context of bioterrorism are agents that are vector borne or that normally cause disease in animals. These are the pathogens that the terrorist would like seek to facilitate transmission to humans - anthrax is a good case in point.

So in 2001, right after the 9/11 attack, and before the anthrax events, we created the Center for Biodefense in recognition of the possibility of bioterrorism. Since then we have received several very large research grants from the National Institutes of Health, which I'll go through briefly, to help support that kind of research at UTMB. I'll tell you a little bit about what we're doing with those funds here at UTMB in response to this national crisis.

At present we have about six research programs or centers that are focusing on the problem of emerging infectious diseases, including two World Health Organization Collaborating Centers, that are working together under the rubrics of an newly established institute, the Institute for Human Infections and Immunity, here on the UTMB campus.

These include the Center for Biodefense and Emerging Infectious Diseases, which is the largest, that is focused primarily on the threat agents related to bioterrorism, but also is carrying out research on naturally emerging infectious diseases such as the H5N1 influenza virus I'll talk about more momentarily. This center is supported primarily by a very large, approximately $50 million, grant from the National Institutes of Health: the Western Regional Center of Excellence in Biodefense and Emerging Infectious Diseases. This grant supports research at UTMB as well as a variety of other partnering institutions in the six-state region, as you can see here on this slide, all within this five-state region.

The critical thing to mention here is that one thing we have really learned about and come to appreciate is the power of collaboration. This consortium involves UTMB, Texas A&M, UTHSCH, UT Southwestern and virtually every one of the major institutions in this part of the country that are typically competitors for federal awards. Under this grant, they work together in a very good and positive way, taking the strengths of each to apply them to the problems before them. Now, you can see here this grant is bringing in about $12 million this year from the National Institutes of Health to Galveston. But you can see that less than half of those funds actually remain in Galveston, whereas the rest are being subcontracted out to our partner institutions to allow this to happen.

This Western Regional Center of Excellence grant is supporting the development of vaccines, diagnostics, and drugs (therapeutics to act as countermeasures to these biodefense threats) primarily the so-called Category A select agents. You'll hear more about that from Dr. Peterson shortly.

In addition to the UTMB Center for Biodefense and Emerging Infectious Diseases, we have the Center for Hepatitis Research that also operates also under a consortium grant from the National Institutes of Health (in partnership with UT Southwestern, the Southwest Foundation in San Antonio, and Johns Hopkins), as well as a contract to our institution here for testing antiviral drugs for the NIH that might have activity against hepatitis C virus specifically. This has been a very successful center, in operation here at UTMB since 1997, generating a great deal of new information about the virus; new ways in which you can grow the virus in cell culture and test the virus for it susceptibility to new drugs as they're becoming available.

The hepatitis center, which I direct, is part of a national network  of such NIH-funded centers‑ and this is one of the first centers in the network - is going to be very a important part of a new generation of therapeutics that will be coming available for hepatitis C in the next few years. I point out this example to show that we're doing more than biodefense, much more than just bioterrorism-related research at UTMB. We are addressing not only hepatitis C, but a whole panoply of emerging infectious diseases.

We have the Sealy Center for Vaccine Development that was founded under Dr. Stanberry's leadership with the use of institutional funds from the John Sealy Memorial Endowment for Research, but which has since achieved substantial funding from the NIH and the Department of Defense to support the development of vaccines at all phases. It is now also supporting through an arm's-length relationship, the "National Network for Immunization Information", which is a leading global source of valid vaccine information. They run a fantastic website. It's been on this campus, or associated with this campus, for a little over a year-and-a-half, and has been cited for excellence by the World Health Organization.

Then there are the two World Health Organization collaborating centers, one focusing on Tropical Medicine and the other on Arboviruses and Encephalitis Viruses. Now, to be a collaborating center means you are recognized by the World Health Organization for your specific expertise, your excellence, and your ability to help the rest of the world to deal with these issues.

We are very fortunate to have a generous endowment, the James W. McLaughlin Endowment for Infection and Immunity, that was bequeathed to UTMB in the '50s and that has supported over 400 students and research fellows working in this area over the past half centruy. It's been a real bedrock of support for us, helping provide support for many worthy trainees.

Then there is the $110 million grant from the National Institutes of Health to construct the Galveston National Laboratory (GNL), the construction that you see right outside the building here. I'll tell you a little bit about this building. I want to say at the outset, though, that this is a building that's going to cost much more than that $110 million. The overall cost will be closer to 170 million before we're done. And we've been very grateful to the number of foundations that have very graciously helped support this activity here on the UTMB campus, as well s the university in its support for the $57 million required in matching funds by the National Institutes of Health.

I want to be sure to mention the Brown Foundation, the Fondren Foundation, the Keck Foundation, and the Kleberg Foundation, because the generosity of these foundations has provided us with the ability do the kind of things that we're going to show you this afternoon.

This slide shows the construction site for the GNL. This will be a building that will be seven stories tall when it's complete. And it will connect with this building just to the north of it that right now is the most sophisticated biocontainment laboratory in the southwestern United States. When this building is complete there will only be two other research facilities, biocontainment research facilities, with equal sophistication to this in the entire United States, one of those being the U.S. Army Medical Research Institute for Infectious Diseases at Fort Dietrich, and the other being the BSL4 laboratories of the Centers for Disease Control in Atlanta. Another such laboratory is being planned by Boston University, and if it is successfully constructed, together with the GNL, these two laboratories will be the only non-federal laboratories with that level of expertise and capability in the U.S.

You can see here that GNL is going to really dwarf the Keiller building that currently houses our biocontainment laboratories that will sit right next to it. Here is the Robert E. Shope BSL4 Laboratory, our current BSL4 (maximum biocontainment level) research laboratory and the only one of its type on an academic campus in the U.S. Now, BSL4 space is the kind of research laboratory space that you may have seen in the movie Hot Zone, in which individuals work in what looks like spacesuits. You saw a little bit of our existing BSL4 space in Glenn's movies at lunchtime. The GNL will have a substantial greater amount of BSL4 research space, as well as BSL3 research space (a lower level of containment for potentially airborne pathogens).

BSL4 biocontainment laboratories are very rare, and the scientists that know how to work within them, even scarcer. There are probably less than a hundred well-trained scientists worldwide that know how to work safely and have deep experience in these kinds of facilities. And we figure we have about 10 percent of that world's population, if not more, here at UTMB right now.

This is a research facility that is designed to be as secure as possible. There's two double concrete walls, airtight walls, that separate the inside of the facility from the outside. The virus is actually handled within special biocontainment cabinets within the laboratory. The individuals work in suits with air being fed into the suits to protect them against the inadvertent escape of even a small amount of virus that might come out of these biosafety cabinets. At almost all times, there is no contamination of the air in the facility. The suit is just one of a series of redundant protection mechanisms, each very important, to keep the infectious agent in the lab, and to protect the worker from it.

When individuals leave this laboratory they go through a chemical shower. They're in the shower for about seven or eight minutes so that anything that may have been deposited on the surface of their suits is washed off. This is serious stuff. The viruses that they're working with within this facility are viruses that are potentially fatal if an infection occurs. And they're viruses for which there are no vaccines and no antibiotics; no ready cure let alone treatment.

So it's essential to have this kind of containment in order to do the research that needs to be done to develop the vaccines and the antiviral drugs we need to take these kinds of agents and put them on the shelf. These are thus very sophisticated laboratories with a tremendous amount of engineering above and below the research space to take care of the waste that comes out of these facilities. All the waste is cooked or filtered before it leaves the facility and to make sure the air going in and especially coming out is sterile.

We have substantial training facilities: this slide shows a mock BSL3 laboratory, and this an engineering mockup of a BSL‑4 lab control system. Our ability to train scientists and engineers in BSL3 and BSL4 biocontainment practices here is recognized nationally. We've been sought out by other universities or federal agencies that with to develop expertise in this area. In fact, right now we are training the future lab manager for the National Institutes of Health BSL‑4 lab which is to be constructed in Montana.

So that, then, is the background within which we're working here. Now, I'd like to spend the last five minutes here of my time talking a little bit more about bird flu (or "highly pathogenic H5N1 avian influenza", as the virologist would call it) and to try to put what I've told you already into specific context with this infection. We are poised to work with the avian flu virus here on campus now. Adjacent to the GNL construction site, the Robert E. Shope BSL4 Laboratory which I described previously provides us with the capacity to do research with this virus. And research is urgently needed for a vaccine or therapeutic for this very real, natural infectious disease threat.

As of the middle of this week there have been 133 cases of H5N1 influenza reported in humans in Asia. Of those 133, 68 have died. These were almost all children and young adults who were in close contact with poultry. If you look retrospectively ‑ and some scientists with foresight, like Dr. Rob Webster at St. Jude, have been following this for some years ‑ this virus has been expanding in both wild and domesticated bird flocks in Asia, such that now this virus is widely disseminated throughout all the chicken and duck populations that are being raised in Asia, and, moreover, has spread into the wild waterfowl populations. So now it's being carried by migratory birds.

This virus H5N1 is a typical influenza virus. And what many of you might not realize is that flu, the influenza virus that comes around every year, is basically a bird virus. Humans get it as a bit of an accident. It's not primarily a human virus, it’s another "zoonotic" virus. But there are strains that have become relatively well adapted to humans, and that's what we see every year.

Now, occasionally one gets genes imported from influenza viruses infecting birds into the human virus pool. And when that happens we have the potential for a very substantial epidemic, or what we call a pandemic. The last two pandemics happened in the '50s, and about '68, when Asian flu and the Hong Kong flu viruses suddenly appeared on the scene, both ostensibly from sources in Asia. Now, those were serious outbreaks, but they were nothing like the 1918 "Spanish influenza" outbreak that was much more lethal.

What we know now about the current H5N1 virus is very sobering and this information has only been determined in the past few months. These newly derived data suggest that the 1918 virus was actually very similar in many ways to the H5N1 bird virus now circulating among birds (with occasional transmission to humans) in Asia. It was a bird virus that jumped quickly (and for still unknown reasons) into human populations.

The H5N1 has been expanding among avian flocks in Asia, jumping occasionally to those having close contact with infected domesticated ducks and chickens. As I have said, it has to date killed about half of the individuals that it has infected. I think the average age is about 11 years for those who have died ‑ that is, mostly children. So this is not a virus that is attacking the elderly, those with respiratory infections, or the immune-compromised as you might think of flu doing normally. It's attacking normal healthy people in Asia, as I said before, almost always those in very close contact with birds.

Now, if we look back over the past few years we can see that the birds have been sustaining greater and greater numbers of infections with this H5N1 virus, both in wild as well as domesticated aquatic and terrestrial birds‑‑ ducks and chicken. The latter numbers have become truly extraordinary in the past year. Unlike the normal avian influenza viruses, this highly pathogenic H5N1 virus is killing the domesticated birds at a very high rate, and it has also begun to kill the the wild waterfowl as well. That's very unusual.

I referred previously to the 1918 epidemic, which was really horrendous. This is a picture of a makeshift hospital at a camp in Kansas in September of 1918. This virus emerged at the time of World War I and it spread rapidly around the globe. No one's actually sure how many people were killed. The estimates run anywhere from 20 to 50 million. In the United States it was somewhere close to 700,000, a huge number for USA, which had a much smaller population in 1918 than it does today.

As with the H5N1 flu we see in Asia today, almost all of the deaths were in individuals under the age of 45. These were not the elderly that we normally think of as being at risk with flu. That's something we just don't understand. This virus appeared to cause an unusually aggressive infection when it entered a normal healthy adult, leading to respiratory failure and death, often within 24 hours ‑ very, very fast. Now, although it's controversial, and there is a lot of debate about it, I think many of these cases were probably due to primary flu infection and not a secondary bacterial infection, although that's debated.

Very recently, investigators at the Armed Forces Institute of Pathology at the Walter Reed Army Medical Center in Washington have been able to recover the genetic material from the virus that killed a woman who died of flu in 1918 in Alaska and who was buried in the permafrost. They were able to recover the genetic information from the lungs of this individual and determine the genetic sequence of that virus in 1918 - a bit of viral archeology if you would. And, as I said, we know now that this virus was, by all its genetic fingerprints, a bird virus that suddenly was able to achieve the ability to be transmitted to and among humans.

You can see the impact of this infection in 1918 on the mortality rates in the United States. The average life expectancy dropped significantly in the U.S. as a result of that pandemic. And you can see here that the death rate due to infectious diseases just about doubled. If you put that death rate against the current death rate, either infectious or all causes, you could see it would be an enormous increase.

The human cases of H5N1 influenza that have appeared in Asia so far have a number of very important features. First of all, as I mentioned, the case fatality rate is very high, about 50 percent of the infected persons have died as a result of the infection, even though some of these patients were treated with Tamiflu, which is an antiviral that has activity against most strains of this virus in cell culture. At present it looks as though almost all of these individuals have acquired their infection from birds, usually from close contact during the slaughter of chickens or eating chickens that may have been infected and not adequately cooked.

But there's at least one incident, one cluster of cases that occurred in Viet Nam within a family where it looks as though the virus may have acquired the ability to be transmitted between members of the family. And that's the thing that virologists and public health experts are all worried about; that is, the potential for the virus to acquire the ability to be easily transmitted between people. That would make the difference between what we have now, a very serious public health menace in Asia, and what would be a global health emergency.

Right now the H5N1 virus lacks the ability for efficient spread among humans, although it spreads readily among birds. Some virologists feel that that ability is only a few mutations away and that the clock is ticking. The problem is only we don't know exactly what time it is. Other virologists feel, well, that the virus hasn't been able to achieve this ability to be readily transmitted among humans yet, so it may never do be able to do so. Unfortunately, only time will tell us which group of scientists has it right. So if you look at pandemic flu it's a bit like hurricanes. You know they're a threat, you know it's going to happen sooner or later, but you don't know if it's going to be this week or next week, this season or next season.

Nonetheless, the World Health Organization has put together a color-coded panel of pandemic threat. Staring over here on the left is Phase 1, when there's no new virus in humans and those in animal populations have a low risk and over to here in Phase 6, where you're in a frank pandemic with increased and sustained spread in the general population. On this scale, we're probably in Phase 4 right now. We have extensive spread among animals. We have limited spread among humans, small clusters and localized. And the question is where it is going the rest of this year and next year…

Now, how could H5N1 reach Texas? After all, we're a long ways from Asia. Well, migratory birds are probably the most likely way in which that could happen. But bear in mind we have a number of direct flights from Dallas and Houston to Asia and that an infected individual, be he or she infected with the SARS virus or with avian influenza, if we got to that point in the pandemic, could arrive here very suddenly unbeknownst to us.

In addition, there's always the potential for birds to be imported, even smuggled, into this country and other countries. Birds with H5N1 infection have been recognized in quarantine at Heathrow Airport in London recently and exotic birds were discovered in Brussels recently that were being smuggled into Belgium wrapped in a rug. They weren't infected, but it just shows the risk that you have for bird traffic.

Now, if you look at the major flyways of migratory birds, you can see that they are global in their span. Many of you probably know this, those of you that are bird watchers and follow bird movements. But you can see that from infections among waterfowl in Southeast Asia, there has been a spread of the H5N1 virus in flocks along migratory routes up into central Asia into Turkey. It seems very clear that the virus is in the flyways moving with the birds.

The question for us to ponder is whether the H5N1 virus will reach the United States via an airplane, or instead travel on feathered wings via the east Asia-Australian flyway, and then the Pacific-Americas flyway into central southern United States, as shown here. There's a real need for us to begin doing more effective surveillance for this virus in the United States, including Texas.

Now, a few weeks ago I had the interesting experience of hearing the President of the United States present a half-hour lecture on pandemic flu at the National Institutes of Health, and along with it a summary of the federal government's pandemic preparedness plan. The President's plan is based on three pillars. One is preparedness in communication. Another is surveillance and detection, an area where we need to have a great increase in our ability to do these things. The third pillar is response and containment, another area where we are woefully inadequate at this point in time.

What types of countermeasures do we have available in the event of a pandemic? The NIH has actually made a vaccine against H5N1, that is about 2 million doses of it, and it's been tested. It works, but it requires a high dose maybe two doses. So that's not a lot of virus vaccine to protect 300 million people in the U.S. If you look at the United States we have the capacity to make in any one year about 55 million doses of vaccine for influenza. So we can cover about a sixth of the U.S. population with our manufacturing capacity in this country. We need to do much more to be ready with a vaccine should a pandemic happen.

The President's plan calls for the procurement of a stockpile of the anti-flu drug, Tamiflu. It's not there yet, however, and when we do get it, we will only have 40 million doses. It requires a daily dose to protect an individual, and as I mentioned above its potential effectiveness as a therapeutic is not without question.

In the face of very limited countermeasures, what we can do is improve our surveillance and rapid reporting capacities. The CDC is working hard with the various state health departments to do that and to develop rapid response teams that have could antiviral drugs (and possibly vaccine) that could be shipped to a site in an effort to contain the infection, or delay its spread, if and when an outbreak of infection were to occur in the U.S.. But the challenge is to properly fund the human resources, and to carry out the planning, coordination, and cooperation required among multiple agencies. In this case, the Department of Health and Human Services, the Department of Homeland Security, the Centers for Disease Control, the NIH, the USDA, the Department of Agriculture ‑ the list goes on and on just within the federal government.

So here in Texas we have been working with our partners, and it's been a very interesting and very pleasing experience thus far to work very closely with the group in Houston at the Center for Biosecurity and Public Health Preparedness and in College Station at the National Center for Foreign Animal and Zoonotic Disease Defense. We have been developing a concept for rapid, real-time surveillance of influenza in Texas, something that we have proposed to do in close coordination with the Texas Department of State Health Services and in partnership with a company from California called Ibis that has developed very novel technology called TIGER by which it seems possible to rapidly identify and type influenza viruses, in culture certainly if not directly in human and animal samples.

Without going into the details, this is a very complex, automated reverse transcriptase, polymerase chain reaction-mass spectroscopy device that takes a sample and four hours later tells you what virus is in it. It gives you a pretty exact fingerprint of the genetic makeup of that virus. The output is rapid, it's real time, it's capable of high throughput, and the output is digital so it can be shared in real-time over the internet. What we propose is to site such instruments at a variety of locations so that we can sample the influenza viruses present in the community: in emergency rooms, in hospital and community-based practices, as well as in the avian species that are flying through the state, or that are being raised in the state for commercial purposes. Our vision is to have all these facilities capable of exchanging such data on a real-time basis, and to develop a network for surveillance that would be the envy of the rest of the United States and an example for the world.

That's the proposal that we're working on, and we are in the process of trying to make it a reality. Now, the reason we can do this is that we have the laboratory facilities that I've reviewed with you earlier, and we've had the support of the NIH and several generous foundations that have allowed us to pursue these activities.

So at this point I'd like to ask Dr. Scott Weaver to come up. Scott is a professor in the Department of Pathology and an expert on what are called alphaviruses. They're small RNA viruses that infect humans and are transmitted typically between animals and humans by mosquito populations. And he'll tell us all about it. Thank you.

 

Dr. Weaver: Thank you, Stan. I'm going to tell you a little bit about a virus that you probably haven't heard very much about before. It's a virus called Venezuelan equine encephalitis virus. And I think it's a nice example of, first of all, one of the viruses that we've studied here for quite some time at UTMB.

It's a virus that we've known for a long time has the capability of emerging naturally to produce large epidemics of disease in people and in equines, such as horses, donkeys, and mules. And we've also known for a long time that it's a very potent biological weapon. It was highly developed during the Cold War, for example. So this is a virus that, based on our expertise and experience prior to 2001, studying it as an emerging pathogen left us in a very good position to take a leadership role in the biodefense efforts to try to prevent this virus from being used by terrorists or rogue states in the future.

So why is this virus a biological weapon? Well, it has several properties that lend it to that use. First of all, we know that it was highly developed during the Cold War, both here in the U.S. and in the former USSR. It's readily available from natural sources. A terrorist doesn't have to break into a laboratory to get their hands on this virus. They can go out and get it in nature fairly easily. It replicates very well in cell cultures, and it's very stable. So it's a very user friendly virus from a laboratory standpoint. It's highly infectious by aerosol. And this is a property that most of the potent biological weapons share. In other words, if you generate an aerosol of very tiny droplets containing this virus you can very efficiently infect large numbers of people. It produces a very debilitating, sometimes fatal disease.

It produces immunosuppression, so it predisposes people to a secondary infection, with a bacterium, for example. And many people who survive the disease have permanent neurologic disease for the rest of their life. If you introduce this virus into the right place with mosquitoes and horses, for example, you can develop a secondary epidemic through the natural emergence process that I'll show you in a moment. And then there's no licensed human vaccine or effective drug against this virus. So we have no way to prevent infection or to treat an infected person. And, finally, we know that this virus can be manipulated using genetic-engineering techniques to probably make it even more virulent and to kill more people and horses if the person with the appropriate expertise went about this the right way.

So, in general, what can we say about the way that emerging infectious diseases occur? What are the factors that result in these emergences? Well, there are a number of them in common. One is deforestation. And the reason is that many of these viruses and some bacteria that we consider to be emerging pathogens have their natural home in forest environments, especially tropical forests. They're zoonotic agents, which mean that they normally infect wild animals, and people are not their natural hosts.

When we destroy their forest habitat we - first of all, we invade their territory, and, second of all, we sometimes force them to find a new way to be transmitted, which can be more dangerous for us. The second factor is that we're building large cities. And, in fact, many of the most rapidly expanding cities in the world occur right in the tropics. So we're putting large populations of people right in the middle of the territory where these viruses occur and offering the virus a perfect opportunity to find better ways to infect people.

As Stan mentioned, an infected person or an animal can get onto an airplane anywhere in the world, and within a day they can transport the virus or the bacteria to a new location to start a new outbreak if person-to-person transmission can occur or sometimes animal-to-person transmission.

Environmental changes that we make on the planet can have a dramatic effect on the ability of these viruses to spread and emerge. For example, this is a tire dump here. And we know that in 1985 a mosquito called Aedes albopictus colonized Texas, coming from Asia, in used tires that were imported for retreading in the Houston area. So this mosquito appeared in Houston in 1985 and has spread throughout much of the United States now. And we know that it's a very potent vector of many of the viruses that are considered threats in this country, such as West Nile virus and also Venezuelan encephalitis.

And, finally, as Stan also mentioned, the viruses and also the bacteria have the ability to evolve much more quickly than we can evolve our natural host defenses to combat the infections that these agents cause. So we can't keep up with them in our natural evolutionary processes. The only way that we can attempt to do this is with our science.

A Venezuelan encephalitis virus actually has a history right here in Texas. In 1971, through more or less a natural emergence process, this virus was introduced into South Texas. And over the course of about three months it infected about 300 people in South Texas and killed about 1,500 horses in the state. There was a massive vaccination program that actually extended almost throughout the United States and a massive mosquito control effort here in Texas spraying Malathion insecticide out of airplanes all over the coastal regions that was put into place to control this outbreak in 1971.

The history of natural outbreaks from the virus probably dates back to about the 1920s. And most of these outbreaks have occurred in northern South America, and they've involved up to several hundred thousand horses and people over a period of a few months to a few years. One of the outbreaks began in 1969 in Guatemala and El Salvador, and this is the one that eventually spread up through Mexico into Texas and caused that epidemic in 1971 here.

But the curious thing about this virus is that after it causes these massive epidemics it disappears for periods of ten, sometimes up to about 20, years and can't be found anywhere in nature. So for a long time the main goal of our research program was to try to understand where this virus comes from, how does it emerge out of nowhere, cause a major epidemic, and then disappear for decades after that.

And what we've learned is that the progenitors, the viruses that cause these outbreaks, actually are viruses that are found only in forest habitats. These are viruses that use small rodents as their reservoir hosts. These are the animals that are responsible for maintaining the virus over long periods of time in a cycle involving mosquitoes in a forest habitat. And these mosquitoes are a type of mosquito that very specific to forest habitats. It rarely ventures very far from a forest.

So, for that reason, this kind of cycle occurs more or less silently in tropical rain forest habitats throughout the New World neotropics and also in Florida in this country. This more or less silent cycle goes on without anyone's knowledge unless they go looking for it. And then periodically this virus finds a way by mutating to allow it to infect much more efficiently horses and to generate large amounts of virus in the bloodstream of a horse.

Once it mutates to allow it to replicate well in horses, horses can serve as very efficient amplifying hosts. And different kinds of mosquitoes, the kinds that you usually would find in a pasture-type habitat where you'd find horses, especially in coastal areas, are very efficient at biting an infected horse. After about a week of incubation they can either bite another horse to continue the cycle or they can bite people in a process that we usually call spillover. People are not really part of the cycle, but they tend to live near horses so they get infected accidentally and often with very severe consequences. So this cycle can go on as long as there are available susceptible horses and lots of mosquitoes. And so the outbreaks usually occur during a rainy season in places where there are horses such as ranch habitats.

Now, we've been particularly interested recently in some activity of this virus in Mexico. So the history of activity of VE virus in Mexico, as I mentioned, began here in 1969 in El Salvador and Guatemala where a virus probably that actually resulted from the use of a bad vaccine escaped into the environment, spread up the coast here in this horse-to-mosquito transmission cycle, across the Isthmus of Tejuantepec, up here to the Gulf Coast, and then moved right up into Texas across the border in 1971 and caused that epidemic. That's the only recorded history of Venezuelan encephalitis activity in Mexico until 1993. And in that year another small epidemic occurred here in the coast of Chiapas state near the Guatemala border. Then another outbreak occurred in 1996 just to the north in Oaxaca State, also on the Pacific Coast, and another outbreak was detected in 2002.

There were a couple of important questions for us to answer about these outbreaks. First of all, what led to the sudden appearance of the virus in 1993? We know that the only previous outbreak was caused by the use of a bad vaccine. We didn't realize that there was the potential for natural emergence of this virus in Mexico, and we didn't really know how it could happen. The second question, most important to us and to the USDA, was what was the potential for spread into the U.S. because you can see that the locations of these outbreaks are right along the path that the virus spread up into Texas in 1971.

We have a major research program in this area to try to understand what's going on now in Mexico. And it's turned out to be quite interesting. What we've learned, partially through collaboration with a USDA scientist who specializes in using satellite imagery to study infectious diseases, and also from our own field studies, is that the area where these outbreaks occur here on the coast, the Pacific Ocean is here, on the coastal plains of Mexico has been severely deforested during the past few decades.

This a satellite image that doesn't contain colors like you would see with your naked eye. These colors represent different portions of the infrared spectrum. And the red and orange colors here represent heavily forested areas that remain in the mountainous areas just north and east of the coastal plain. But the green and blue colors here represent pastures primarily and other disturbed habitats in the coastal plain. So you can see that there's almost a complete absence of forest now in this area.

What we've learned has happened is that originally there were forest cycles, like I showed you in the cartoon a moment ago, where the virus was transmitted by rodents by a certain mosquito that lived in forests here on the Pacific coast of Mexico and Guatemala. But the habitat for this mosquito, called Culex taeniopus, was destroyed here. Basically we forced the virus to find another way to be transmitted by mosquitoes. In other words, we told the virus, you have to adapt to another mosquito if you want to survive here.

Well, what mosquito might that virus use instead of the forest vector? Well, we've discovered that it's this mosquito, Aedes taeniorhynchus. Why would the virus pick this mosquito? Well, there are several reasons for this. First of all, it's the most abundant mosquito in the coastal areas of Chiapas state and Oaxaca state in Mexico. Those of you who are from coastal areas here on the Gulf Coast of Texas are very familiar with this mosquito because it's also usually the most abundant mosquito anywhere near salt marshes in this part of the world. It was probably the most important vector in 1971 when the virus came here.

Unfortunately, this is a mosquito that, instead of preferring to bite rodents in forest habitats, it prefers to bite large mammals like horses and people and it lives outside of the forest in marsh areas and pasture areas. And it's a highly efficient vector for the epidemic transmission from horse to horse and horse to person. What we've discovered in the process of studying the genetics of the virus is that the virus very recently adapted to infect this mosquito more efficiently and to use it as a vector in Mexico. So we've forced the virus to come up with a solution to continue its transmission cycle that's detrimental to us because the vector now is more likely to bite people and horses.

Now, how does this mutation that we discovered affect the ability of the virus to infect a mosquito or to infect horses and people and cause disease? Well, that's a very difficult question to answer. But we're starting to make some progress on that. What we have discovered by doing some structural studies using a process called cryoelectronmicroscopy we've determined the structure of the virus particle here. Here it's magnified for you about a million times to a resolution of about 8.7 angstroms. This is the highest resolution that's ever been produced for an alpha virus, a member of this group of viruses.

What we can see here by color coding different parts of the virus is that the red part here on the surface that forms these projections or spikes here is called the envelope glycoprotein number 2. The mutations that allow this virus to infect mosquitoes better and to infect horses better lie on the surface of this E2 protein. This is actually a reconstruction done with the vaccine strain of the virus, which is safe to handle in a normal laboratory environment. In about two months we're going to be able to do the same kind of structural studies using the wild type highly dangerous virulent virus that causes the outbreaks.

The reason for that is that we're developing a new facility on campus, thanks to gifts from the Keck and Kleberg Foundations, that's going to allow us to put one of these microscopes for the first time anywhere in the world into a high-security level 3 environment here on our campus. So we'll be able to study almost any virus that's amenable to this kind of structural study in the high containment safe environment here on our campus.

To return to these themes about emerging viruses and pathogens and how Venezuelan encephalitis fits into this picture, I show you that these viruses have their origins in forest. So when we start cutting down their forest habitat, when we invade their territory, we do two things. We increase our own risk of infection and contact with the virus, but we can also force the virus to find a new way to be transmitted in a different kind of habitat. And that can have bad consequences for transmission to people and horses.

We build cities right in the middle of these habitats. For example, we do field studies in a place called Iquitos, Peru, which is a city of 400,000 people right in the middle of the Amazonian Rain Forest. And we've detected a lot of infections in that city with this virus. Although we haven't documented this in the past, just like many of these other pathogens, a person who becomes infected with this virus can get on an airplane in Maracaibo or Caracas, get off in Houston, and if they go to a ranch where there are mosquitoes and horses they could initiate the epidemic cycle right here in Texas very easily.

As I showed you, this virus through single mutations, which RNA viruses, viruses with a kind of genetic material that influenza and VE have, can mutate very rapidly and find ways to infect new hosts via these mutations.

 

Dr. Peterson: At UTMB in Galveston, we have built an Aerobiology Facility within our Animal Biological Safety Level 3 Suite for testing new drugs and vaccines against anthrax, plague, and other diseases acquired via the respiratory tract. In this brief presentation, I will illustrate some of the work that we have begun as a defense against the threat of bioterrorism and emerging infections. We have done a lot of extensive evaluation of a monoclonal antibody against anthrax toxin in small animal models of inhalation anthrax here at UTMB. But before I show you some of the data, I'll just show you some of the obstacles that we face in this type of research today. I'm not here to complain - it's just the facts of life in working with select agents.

We can't simply go into the laboratory today like we used to and start working with Bacillus anthracis or other select agents. Everyone in the laboratory, including myself, has to obtain a background investigation from Department of Justice, that is, a background check by the FBI. I'd already had one many years ago because my fiancé worked for the FBI. So back in J. Edgar Hoover's day, even the friends and spouses of FBI employees had to be investigated.

In addition, there are many, many obstacles to the work that delay our work, and inherently increase the costs. I'll just show you some of the types of special equipment that we use to protect ourselves. We wear Tyvek suits with battery-powered respirators that filter the air that we breathe. All of our work is performed in restricted access BSL3 facilities, which have a high-level of biocontainment that Dr. Weaver mentioned.

All the air in the facility is filtered through large HEPA filter units. It's quite a redundant process to ensure safety. Our biosafety cabinets have gloves so that my personnel and I can work inside this protective environment. Our Class III biosafety cabinet is connected to a lower-level Class II biosafety hood.

We have aerosol equipment into which we place small animals and infect them by the respiratory route. Then, we evaluate the effectiveness of therapeutics and vaccines. The infected animals must be housed in special ventilated cages that have HEPA-filtered air input, as well as HEPA-filtered air exhaust.

Figure 1 illustrates some of the periodicals showing the personal protective equipment worn by first responders helping in the cleanup following the intentional release of anthrax spores in Washington D.C. and New York City. The weaponized spores were distributed in the U.S. Mail in letters to public officials (see Figure 1). A total of 5 Americans died from inhalation anthrax among approximately 18 with clinical symptoms.

peterson fig 1

At UTMB in Galveston, we have research programs dedicated to the development of new diagnostic tests, novel drugs, and improved vaccines against anthrax and several other bacterial and viral agents of bioterrorism. Importantly, UTMB provides training to students, who become tomorrow’s scientists (Figure 2).

peterson fig 2

Along with my colleagues at UTMB, Drs. Catherine Schein, Scott Gilbertson, and Alfredo Torres, we are developing a new drug that blocks the edema toxin secreted by B. anthracis. Figure 3 illustrates the molecular structure of anthrax edema toxin. By neutralizing the lethal toxin, the virulence of B. anthracis is reduced. The model shown is from Dr. Schein’s structural research in which she and her team dock inhibitory compounds in the active site of the toxin. Dr. Gilbertson is an organic chemist who has synthesized several hundred related compounds in an attempt to develop superior antitoxic drugs.

Fig. 3. Structure of anthrax edema factor.

peterson fig 3

Figure 4 summarizes the method used by one company (Avanir Pharmaceuticals, San Diego, CA), with whom my laboratory collaborates, to evaluate a new human monoclonal antibody against protective antigen from B. anthracis. Basically, the lymphocytes from human volunteers immunized with Biothrax vaccine are cloned and the antitoxin gens are then expressed in a cell line (Chinese hamster ovary cells). The human anti-PA antibodies are overexpressed and purified to homogeneity. We have been testing the protective capacity of these human antibodies in small animal models of inhalation anthrax.

Fig. 4. One example: a new therapy for Anthrax AVP-21D9 Synthesis Xenerex™ Technology

peterson fig 4

But before I show how protective these antibodies are for experimental animals with inhalation anthrax, what kind of problems do we face due to new federal regulations? Figure 5 lists some of the rules and criteria that we must meet in order to perform studies with B. anthracis. First, all personnel, including myself, must have a security clearance from the U.S. Department of Justice (FBI background check) that can take up to 9 months. As a qualified scientist, I must have completed a select agent registration application, arranged for one or more laboratory inspections, and arranged from controlled shipment of the agent with appropriate federal agencies. Each academic institution must arrange for building security, review of scientific work by an institutional biosafety committee, and maintain current registration status. As an investigator, it is my responsibility to acquire funding to purchase appropriate safety equipment for handling these pathogens, acquire HEPA-filtered housing the infected animals, and ensure that all personnel are properly trained and attired for performing the work. All animal research is overseen by a faculty committee known as the IACUC.

peterson fig 5

Figure 6 shows the positive pressure respirators worn by UTMB personnel in the Aerobiology suite where pathogens are aerosolized under carefully controlled conditions, using the latest biosafety equipment to minimize risk to personnel and the environment. Figure 7 shows some of the biosafety glove cabinet equipment that is used to protect personnel and the environment from the aerosolized pathogens. Figure 8 shows some of the HEPA-filtered ventilated safety cages for housing infected animals while testing new drugs and vaccines.

peterson fig 6

peterson fig 7

peterson fig 8

Finally, we get scientific results! In Figure 9, we demonstrate that the human monoclonal anti-PA antibody mentioned earlier was highly protective against lethal infection in the rabbit model of inhalation anthrax for 5 weeks and then was still protective against rechallenge for at least two more weeks. Complete protection against death was achieved with as little as 1 mg/kg of body weight. Partial protection (50%) was achieved with as little as 0.5 mg/kg (data not shown). Figure 10 indicates interesting data from other rabbits infected with B. anthracis via the respiratory tract with or without protection by the human monoclonal anti-PA antibody. The results indicate that the animals have few symptoms before death. For example, we did not measure any rise in body temperature in any of the animals. Further, the data indicate that the human monoclonal anti-PA antibody blocks dissemination of the bacteria from the lungs to the blood stream, while most positive control animals develop bacteremia. And die within 60-72 hours. The anti-PA antibody is highly effective in protecting against death in the animals.

peterson fig 9

peterson fig 10

The final Figure 11 shows some of the students and personnel working on the anthrax project. We are very grateful to them for their many hours of hard work and the NIAID and the U.S. Army for providing funds to support this research.

Figure 11. UTMB personnel working on anthrax (2005)

peterson fig 11

 

Question and Answer:

Dr. Lemon: We now have 10 or 15 minutes open for questions. I'll ask my two colleagues to join me here in the center. Perhaps I'll act as emcee and take any questions that we have from the audience on any of these three presentations.

Audience: How does one destroy an infected animal to prevent further spread of infection?

Dr. Weaver: Are you talking about Venezuelan encephalitis or mad cow disease?

Audience: Mad cow.

Dr. Weaver: I think they're generally incinerated right on the farms where the outbreaks occur.

Audience: I was told that didn't destroy the prions. The heat did not destroy the prions. Is that right?

Dr. Lemon: If you are looking at prions in an infectivity assay, it's correct to say that they are very heat-resistant. But they would have to be introduced into the bloodstream of an animal to initiate a new infection. And their ability to survive at the very, very high temperatures of incineration would be minimal. Under conditions of autoclaving, like we normally use for sterilization, they would likely survive. But I think incineration where you're reducing it to carbon, basically, there would not be much infectivity left.

Dorothy Ashby: Do we understand why viral outbreaks do not occur between May and October? And also I understand the Japanese have enough Tamiflu for 40 percent of the population, and we certainly don't have anything like that. Is there a reason?

Dr. Lemon: You're talking about influenza here, of course. Influenza is primarily a disease of cold seasons. We think this is because people are indoors and they're more likely to be exposed to other people's exhaled aerosol. So that facilitates transmission. In terms of the Tamiflu situation, I didn't have a chance to say much about antivirals. There are two antivirals that are effective against influenza that are licensed in this country two classes of antivirals.

One is amantadine or the adamantine class. This is the older drug that is typically used and has been used for many years. The H5N1 virus is generally resistant to amantadine, probably because it's been used in poultry herds in Asia prophylactically. The other drug, which is newer and more expensive, is Oseltamivir, or Tamiflu. Several countries purchased large stockpiles of Tamiflu beginning some months back. I think the Japanese were the first to acquire it for basically their entire population.

There's only a single company that manufactures Tamiflu. It's not easy to manufacture; it's a complicated, expensive manufacturing process that's under patent. Several other countries have opted to buy large stockpiles of Tamiflu. And the United States recently has decided to acquire somewhere around 80 million doses. I believe the President called for a federal stockpile of 40 million and another 35 million to be made available to the states under partial federal subsidy.

It's going to take a while to make that. It may require the construction of a factory here in the United States to actually manufacture the Tamiflu, because it's not manufactured normally in the U.S. So it's a question of supply and demand. Right now the global demand is huge. It's expensive, and relatively few governments have made the commitment, or made the commitment early on, to acquire it. But, remember, as I said before, it is not a panacea.

Audience: I have two questions. One, I wanted to comment about the challenge to evaluate drugs and vaccines against select agents, whether it was possible to get data supporting licensure when you do not normally have human infections, and what strategy you have. And, second, I wondered whether you could comment on the probability that you can create a vaccine against the bird virus which will be effective after a mutation takes place, which is likely.

Dr. Lemon: Good question. I'll let Johnny answer the easy question first.

Dr. Peterson: Well, the Food and Drug Administration established a so-called two animal rule for diseases where it would be unethical to challenge humans with an agent like anthrax. So we will never be able to evaluate these compounds in a clinical study because the natural incidence of the disease is so low that that we can only challenge animals and infer from the best animal models that we have. Consequently, we use three small animal models to evaluate treatments for anthrax: the mouse, the guinea pig, and the rabbit. There are other laboratories in the country that use Rhesus macaques or other non-human primates for this. The Food and Drug Administration will consider results from two successful animal models if they mimic the disease in the human. But safety testing would have to be done in humans.

Dr. Lemon: One of the complications there, of course, is that the FDA will be looking for data that were acquired under GLP rules - that is, Good Laboratory Practices - which is enormously expensive and which no university in the United States is well equipped to deal with right now. We're working hard to try to acquire that kind of capability, but it's expensive. It will be time consuming to get there.

As to your second question, you're referring to the fact that influenza mutates rapidly, particularly in its antigenic hemaglutinin protein, which is the major protein on the surface of the virus against which antibodies that confer immunity are directed. And one of the big concerns has been, if we make an H5N1 vaccine now, like the 2 million doses that the NIH has manufactured, how will we know that that vaccine will protect against the real pandemic strain if it acquires the one or two additional mutations needed to allow it to really be transmitted efficiently?

And the answer there is we just don't know. I think most believe that there would be some level of protection even if it's not a perfect antigenic match. Previous exposure to a vaccine against an H5 hemaglutinin would provide some efficacy. The H5 protein, of course, is something we haven't seen in humans previously. So all of us have no experience with that antigen. It would be a novel infection. Any H5 vaccine would probably provide some level of protection. But, optimally, you'd have to wait to identify the pandemic strain, isolate it, grow it, and prepare a vaccine from that before you have a good vaccine a really good vaccine. That could take many months and might be too late to impact on spread of the infection.

Audience: I've been waiting for someone to mention RNA interference. You said you're doing molecular work. I wonder if you can comment on what's going on there. Because that would answer this question if it would work, would it not?

Dr. Lemon: Possible. RNA interference is a recently discovered phenomenon first identified in plants and more recently recognized to occur as a major gene-regulating process in mammals. It offers some really unique strategies for control because, in theory, one can chemically synthesize a small piece of genetic information - a small "siRNA" - and administer that chemical and thereby disrupt the replication of an RNA virus like flu. And, in fact, there are experiments that have been done in mice that suggest that this might work.

The challenge has been to be able to chemically stabilize the siRNA and formulate it as a drug as a medication. There are probably three companies that are making great progress in doing that in the United States. We're actually partnering very closely with one of them and have now two applications pending at the NIH to obtain NIH funding to test their siRNA compounds against influenza, as well as hepatitis C and other viruses. Good question. Yes, in the far back.

Audience: I'm curious if it would make any difference in thinking about people traveling, particularly in close quarters in an airplane, on elevators, and places where people are close together breathing the same air, but that air has not been circulated you're not getting fresh air. It would cost more for an airplane to keep providing fresh air at the correct temperature. But would taking measures like that make any difference at all?

Dr. Lemon: My guess is that if you put really efficient, high efficiency HEPA filtration systems on planes to take care of recirculating that air through very efficient filters, or even introducing new air, which, as I understand it, would be very expensive in terms of fuel consumption for jet aircraft, that you still would have limited impact. This is because if an individual were to be infected and were to cough and produce an aerosol impacting individuals in close proximity they would likely become infected.

The airplane environment is a major and highly specialized concern. The CDC has recently promulgated new quarantine regulations that will call for the airlines' maintaining passenger lists to identify who's been on planes for some period of time after the flight has occurred - something that they can't do now that the airline industry is saying will be very expensive to put into place. So it's one of those areas where technology is working against us. In many of the examples you've seen here we're suffering from the downside of technology and not the upside. Do you have a comment on that, Johnny?

Dr. Peterson: May I make a comment? One of our medical residents, who was also an astronaut, did a study on American aircraft. And it was surprising to me how many of them use HEPA filtration systems now. Maybe they're not all equipped, but I think this is something that will increase in the future. And there's a lot of concern about downdraft of the air.

Dr. Lemon: How good that is though, to protect you against the person next to you coughing?

Dr. Peterson: I still got a bad bronchitis the last time I went to London.

Audience: With respect to influenza vaccine we still seem to be stuck in the era of biologics. And I'm wondering if you could tell us what keeps us from moving into more modern vaccine development technology for influenza vaccines. And are we stuck with just the surface antigens or will the eight or so core antigens be of any use?

Dr. Lemon: It's a very good question, one that I keep asking myself as someone who hasn't worked primarily in the flu field. Our current vaccines are made by growing virus in eggs and it requires a long lead time to produce the eggs to make the vaccine. And then the virus is inactivated and sometimes fractionated.

It should be possible to produce by recombinant genetic engineering a purified protein vaccine of just the protein of interest, the hemaglutinin and the other key protein, the neuraminadase. However, such vaccines when they've been tried in the past have been poorly immunogenic, probably because the proteins haven't been properly folded or assembled into the proper confirmation or haven't assembled into a particle. In the case of the hepatitis B vaccine, which is a tremendously successful recombinant, genetically engineered protein vaccine, the protein actually assembles into a large particle, which is why it's so immunogenic - so good at raising immunity.

And, yet, I think that with the genetic engineering, and the skills that we have today working with proteins, we should be able to create an artificial flu particle with the right kinds of protein on its surface. As part of the President's plan, there is a major focus on developing new vaccines and bringing flu vaccine production into the 21st century instead of using the 1950s technology that's now used. But it's a huge challenge. It takes years and many hundreds millions of dollars to bring a vaccine to licensure.

Audience: I had two questions. One was on the flu vaccine we have now. I've read some articles that it's really not as effective as it had been originally thought to be the current flu vaccine. And the second question was on your estimate on the probability that this avian flu will make the mutations that it needs to make to be transferred from human to human.

Dr. Lemon: Well, the first question, I think there's been a lot of controversy about flu vaccine for many years. Its efficacy is not what we'd like it to be. I think the major question recently has been how best to use it. We normally give it to people that are at risk mostly older individuals, those that have heart disease or that are immunosuppressed. However, there is a strong school of thought that we ought to give it to young individuals, children, who are the major vectors for transmitting influenza in the community. If we immunize them, maybe we'll see decreased rates of disease in the elderly. And that's something that we could perhaps discuss afterwards.

And the second question, the chance of a pandemic, well, I think the best answer I have heard is that the clock is ticking but we don't really know what time it is. I honestly don't know. I have real concerns. This virus is undergoing continuing evolution as we speak. The rate of genetic change is accelerating. It has an enormous pool of different types of birds and mammals including not only humans but also swine and other domesticated mammals to replicate in. And it's probably only a matter of time before it achieves the ability to be transmitted to humans.

But if you ask ten virologists that question you'll probably get ten different answers. The one thing they would all agree on is that if it did become adapted to humans it wouldn't kill 50 percent of them, as we now see the virus doing in sporadic human infections in Asia. Most likely, it would rapidly become less pathogenic, perhaps with a much lower mortality rate, but one that would still be incredible against our usual annual experience with flu.

Audience: Would you comment on the recent article in, I think it was National Geographic, about the dust storms in the Gobi Desert and Sahara that were blowing in across the Pacific Ocean and bringing grasshoppers to the United States?

Dr. Weaver: I don't think I have any knowledge about a relation of infectious disease to that kind of event, all I can say is that there are examples where changes in weather patterns have a severe effect on the emergence of diseases. Probably the best documented example is a virus that occurs in Africa called Rift Valley fever virus that's been studied extensively. One of the experts on this is a member of our faculty, Dr. C. J. Peters. This is a virus that very clearly emerges following periodic changes in climate in Africa leading to increased amounts of rainfall that can be detected by satellite imagery and by measuring greenness on the planet and so forth.

Disease outbreaks can be fairly well predicted from climate change with that virus. And I think you'll see more cases of that kind of research leading to some predictive abilities in the near future. I just don't know of an example related to the dust storms you're talking about.

Dr. Stobo: Well, I want to thank Stan and Scott and John very much for a very exciting and interesting presentation.