 Thank You Dr. Lambert. Good morning. For people of my generation, or younger, it's hard to imagine the fear that smallpox and polio outbreaks used to instill in people. I was reminded of this when I visited my mother's childhood neighborhood in downtown Chicago this summer, and she pointed out the swimming lake that she was prohibited from using as a child because its water might infect her with polio. In contrast, the greatest distress I face with respect to this virus today is that I have to hold my children down and listen to them cry during the vaccination. We have come a long way from prevention by avoidance to prevention by vaccine in a very short period of time. Our opening speaker, Professor Bill Yoclick from Duke University Medical Center, has been one of the key contributors to our understanding of viruses which has led to this revolution in disease control. Professor Yoclick began his training in biochemistry at Oxford University at the time when the seemingly miraculous activity of penicillin against bacteria instigated intense biochemical research on bacteria. His Doctor of Philosophy research concerned elucidating the mechanism of bacteria multiplication. After postdoctoral work in Copenhagen, he joined the Department of Microbiology in the John Curtin School of Medicine at the Australian National University in Canberra. Here he initiated studies on viral multiplication, first on a pox virus related to the myxoma virus that was being used to control the wild rabbit populations in Australia, and later on Rio virus. He continued studying these viruses and also retroviruses after he became chairman of the Department of Microbiology and Immunology at Duke University Medical Center in 1968. Professor Yoclick's work has focused on understanding the genetic material of viruses and how that material replicates and expresses the information it encodes. Apart from learning about viruses, a major goal of his has been to look for ways to inhibit or abort viral infections. He has worked on interferon, IVT, a derivative of which is an anti-smallpox agent, and ribovirin, an antiviral agent used to control certain respiratory infections in children. Professor Yoclick has served as founder and first president of the American Society for Virology and is editor in chief of the Journal Virology. He is a member of the National Academy of Sciences and the Institute of Medicine of the National Academy of Sciences, and he is the 1991 recipient of the ICN International Prize in Virology. We are honored to have Professor Yoclick open this Nobel conference with his talk on the mechanisms by which viruses infect and multiply in human hosts. Thank you very much, Dr. Hofmeister. It gives me great pleasure to open this year's Nobel conference, the 34th in the series, with the theme of virus, the human connection. And I would like to express my thanks to its organizers for having invited me to participate. In fact, I was beginning to wonder whether I would get a chance to speak this morning. The aims of my presentation will be threefold. First, I would like to review the progress that we've made in understanding the principles of virus replication and the fundamental contributions that Virology has made to our knowledge concerning the nature of genetic material and the manner in which the information that it encodes is expressed. I'd also like to review the nature of the host defence mechanisms against viral infections and the strategies that viruses have evolved to blunt and neutralize such. And finally, I would like to speculate on what might be the growing points of virus research during the next one or two decades and where viruses are most likely to make major contributions to the human connection. You know, what makes consideration of these questions extremely interesting for me is the fact that I was there for so much of it. It started for me in 1947, just over 50 years ago, as I was finishing my undergraduate studies at Sydney University for which the writing of a thesis in biochemistry was required. Now, this was supposed to be a rather substantial thesis, not four or five pages. I don't know whether anybody ever weighed the thesis, but none of us were going to test that. We had about a month to repair it and we're supposed to write on a topic that was given to us. Now, the drill was to set up an appointment with the head of the department, Professor Henry Priestley, who after a few minutes pleasant chat assigned you a topic for which you thanked him profusely. And a couple of days later, you went back and told him that while that topic was superb and fascinating, couldn't you rather write about and here you told him what you would really like to write about and he invariably said, great, go ahead. Now, the topic that I chose was discussion of the work that was beginning to be done by the bacteriophage group at Cold Spring Harbor under the direction of Max Delbrook, work that was the beginning of molecular biology. Many years later, a few of us old timers were standing around during a coffee break at a meeting of the Publications Board of the ASM, the American Society for Microbiology, when I rashly remarked that I thought that when I graduated, I knew all there was to be known about virology. And I expected an argument and I was surprised that they all agreed with me. What a change, what a change from today when 3 to 4,000 pages are published every month in virology journals over 40,000 pages a year. It reminds me of something that Molly Broad, who's president of the University of North Carolina recently said at a meeting, she said, if one took the sum total of human information, the bolus of human information at the beginning of the renaissance, at the beginning of, they say, the 14th century, that sum of information doubled by the year 1750. And it doubled again by 1900. And it doubled again by 1975. And it's going to double again by the year 2010. And by the year 2050, when many of you will be still be active, in the year 2050, the sum total of human information will double every 72 days. Inconceivable, but very likely. My only reaction is, I'm glad I won't be here. Bon appetit. Now, virology actually started almost exactly 100 years ago in the last decade of the 19th century, with the recognition of viruses as infectious agents, or more specifically, as pathogens of animals and plants. The great pioneers at that time were Ibanovsky in St. Petersburg, the first to record the transmission of a disease, tobacco mosaic disease, by a suspension filtered through a bacterial filter. And then Lofler and Frosch in 1898 did the same experiment with foot-and-mouth disease of cattle. And Byering, at about the same time, was responsible for coining the term virus. He considered viruses to be living, but fluid that is nonparticulate. And he coined the term virus, Latin for poison, to describe them. However, of course, it quickly became apparent that viruses were indeed particulate, and the term virus has become the operational definition of infectious particles smaller than bacteria and unable to multiply outside living cells. Now, the primary aim of virology has always been to abort or cure virus infections once they have started, or to prevent them all together. And the means adopted to realize these goals, virologists have attempted to understand in detail the nature of the reactions involved in virus replication with the expectation that sooner or later, one would be found to be susceptible to specific inhibition. And on the other hand, extensive studies were carried out on the nature of the interactions of viruses with their hosts, that is pathogenesis, using the techniques of epidemiology, immunology, cell biology, and the insights gained from the basic studies. The studies of virus replication cycles have yielded fascinating insights into the nature, replication and expression of genetic material, insights that encompass not only the mechanics of these processes, but also their control and regulation. Going to the small size of virogenomes, which encode for something like half a dozen to know more than a couple of hundred genes, and owing to the fact that both virogenomes and the proteins that they encode can readily be identified and measured, as well as produced in quantity and purified, and therefore studied in detail, virology has become the model system pariximals for studies of what has been called, with some hyperbole, the molecular interactions most basic to life itself. Now, these studies had the beginning in the late 30s at Cold Spring Harbor, where a group of outstanding scientists led by Max Delbrouk and Salval Luria and Al Hershey and Seymour Cohen realized that the bacterium bacteriophage system provided the opportunity for synchronously infecting homogeneous populations of cells with homogeneous populations of virus particles, thereby permitting definition in biochemical or molecular terms in a single step cycle of the series or the sequence of reactions involved in virus replication. It's the one step growth cycle, one of the crucial discovery in virology. Before long, another superb group at the Pasteur Institute led by Al Waaf, Jacob, Latage and Monor joined in this effort, and very soon the work of these two groups led for the first time to an understanding of the relative roles and functions of DNA, RNA and protein, that is, of how genetic information is stored, replicated and expressed. And soon this new way of carrying out research, combining by chemical, genetic and biophysical techniques and designing experiments so as to seek a yes-no answer, became known as molecular biology and later as molecular genetics. And when shortly thereafter, in 1948, exactly 50 years ago, Anders Weller and Robbins developed techniques for culturing vertebrate cells and cloning them and Dubeco, four years later, adapted to techniques used for working with bacterial viruses to growing, clarking and measuring mammalian viruses in culture, homogenous cell populations, then virology really began to provide superb models for modern molecular cell biology. Work first with bacteriophages and then also to an ever-increasing extent with mammalian viruses, led to concepts such as replication and replicons, transcription and operons, enhancers, promoters, repressor elements, transcription factors, transcripts, splicing, introns and exons, messenger RNAs, and the nature and principles and control of efficiency and frequency of translation, including messenger RNA capping, and finally, the nature of single signal transduction pathway. Let me briefly expand upon three of these. The first concerns the work leading to the assignment and an understanding of the relative roles of DNA, RNA and protein. Now, the key experiments in this series were the demonstration by Hershey and Chase in 1952 that when bacteriophage infects bacteria, it is the viral DNA that is injected into the host cell, whereas the viral protein remains outside. The demonstration in 1956 by Ghira and Shrum that the RNA of tobacco mosaic virus, TMV, by itself is capable of initiating infection, that is, that the RNA, the genetic material itself, is infectious. And finally, in 1958-59, the demonstration by Brenner, Jakob and Messelsen on the one hand, by Hoh and Spiegelman on the other hand, that RNA capable of hybridizing to one strand of bacteriophage and with an identical base composition to the other, and is present in infected cells, and that that RNA is capable of combining or associating with ribosomes present in cells before infection, that is, RNA that fulfilled all the predicted criteria of messenger RNA. Now, all these three experiments were just absolutely breathtaking in their beauty and in their directness. Now, the same can be said of the papers announcing, next slide please, next slide please, not much happening here. Could I have the next slide? There we are. The two papers announcing the discovery of messenger RNA splicing and they were an amazing sequence arrangement at the five prime ends of adenobarous two messenger RNA by Louise Chow, Richard Jelinas, Tom Broker and Rich Roberts, and at the same time and done completely independently, spliced segments of the five prime terminus of adenobarous two late messenger RNA by Susan Burget, Claire Moore and Phil Sharp, and of course, Rich Roberts and Phil Sharp received the Nobel Prize for this. A discovery that was totally unexpected, there was no predicted or previous theoretical basis for spliced genes. The same thing can be said of the paper entitled DNA related to the transforming genes of avian sarcoma virus is present in normal avian DNA by Dominic Stalin, Harold Varmus, Mike Bishop and Peter Vogt. Again, totally unexpected. The implication, the implications of the discovery that the genome of a tumor virus contains a gene that is a variant of a cellular gene were enormous, especially when additional retroviruses were found to possess variants of a variety of other cellular genes. And indeed, defining that retroviruses are capable of pirating a variety of cellular genes that encode proteins with widely different functions, including cytokines and their receptors, GTP binding proteins, protein kinases and nuclear proteins, including transcription factors, led to the realization that there were all components of a cascade pathway for modifying protein function via highly specific protein-protein interactions. The purpose of this pathway being the transmission of signals resulting from the binding of intercellular messengers to cell-surface receptors, all the way to the complexes of proteins that regulate gene expression. Thus, the vast area of intercellular signal transduction derives from the observation that retroviral oncogenes are modified pirated cellular genes. Now, I'd like to just put two more examples, two more examples, resulting from the discovery of restriction in the nucleases. One is represents the beginning of genetic engineering, and that was by Jackson, Simon's and Paul Berg, by a chemical method for inserting new genetic information into the DNA of simian virus 40, circular SP40 DNA molecules containing, oh, there's a column there, circular SP40 DNA molecules containing lambda phage genes and the galactose operon of Escherichia coli. And the other one is the initiation of the first example of the use of restriction in the nucleases to map patterns of gene expression, and this one, one year late in 1973, was entitled a map of simian virus 40 transcription sites expressed in productively infected cells by George Curry, Malmartin, Lee, Dana and Dan Nathan's, who also obtained a Nobel Prize for this. Now let me now return to one of the aims of these studies that are specified earlier, namely, have these studies led to the discovery of powerful inhibitors of viral replication, inhibitors that can abort and therefore cure viral infections once they have started in the host. And I'm afraid that here progress has been slower, although there have been major successes, like acyclovir against herpes viruses, Ganscytovir against the site of megalovirus, azetothymidine and diideoxynucleosides and protease inhibitors against HIV, and ribovirin against respiratory syncytylvirus and lassofever, and of course there was isodine beta thiosemicarbazone or IBT against variola, smallpox virus. But the major stumbling block here is not lack of targets for all of our proteins being different from host cell proteins, all of our proteins being different from host cell proteins should be easily inhibitable in the same manner that antibiotics specifically inhibit the functions of prokaryotic proteins. Rather the block here is our lack of knowledge concerning protein structure. All these antiviral agents are effective and specific inhibitors, but there are small molecules and as a result even a single point mutation tends to cause loss of susceptibility and thus of inhibitory activity. Now what is needed is larger inhibitor molecules but that requires much more detailed knowledge concerning the determinants of protein structure. As you know it is not possible as yet to determine tertiary protein structure from amino acid sequences, and although the crystal structure of many proteins is now being determined, too little is known as yet concerning the induction, role and significance of conformational changes on enzyme function and on the interaction of proteins with proteins. Thus the cure of viral infections once they have started is still some way off. Now the study of pathogenesis has also turned up a rich load of fascinating information. Next slide please. Now infection with viruses triggers a variety of responses. Among them are non-specific responses including the formation and secretion of interferon. Let me put on my glasses here. I've got one eye that is near sighted, the other one is far-sighted, so if I really want to see I take my glasses off except if there's just in a critical zone where I can't see. Now the non-specific responses include the induction of a synthesis and secretion of interferons, the inflammation inflammatory responses caused by the dispatch of lymphocytes to the site of infection which represents the mobilization of the immune mechanism towards against virus infections, cytologists by natural killer cells and the induction of apoptosis. And it also includes specific responses including generation of cytotoxic T lymphocytes that recognize infected cells by virtue of fragments of viral proteins displayed on their surfaces and the generation of B lymphocytes that secrete antibodies against proteins specified by the infecting virus. These are all complex processes that are induced and regulated by a variety of cytokines that must be produced in by cells in correct amounts. Over or under production of cytokines causes the immune response to be either inadequate or possibly even harmful to the host. Now viruses counteract these processes in a variety of ways most of which have been recognized and characterized only in the last 15 years. Thus, viruses may blunt the effects of interferons, let me get the next slide here, blunt the effects of interferons, interfere with the generation and function of cytokines, defend themselves against the killing of infected cells by interfering with the synthesis and function of MHC class 1 antigens which are the proteins that display the viral protein fragments on infected cells and thereby make render infected cells invisible to cytotoxic T lymphocytes. And there are also viruses that induce proteins that block the activity, the activation of complement, that interfere with the regulation of apoptosis and that express enzymes that synthesize steroid hormones that cause immunosuppression and reduce inflammation and therefore reduce the immune response. Now so far 30 to 40 genes are known to be involved in these functions designed to overcome components of host defense mechanisms and they could well be more than a hundred. Most of those known so far are present in the genomes of the largest viruses primarily the pox viruses and the herpes viruses which have become virtual Rosetta stones for the defining components of anti-viral defense mechanisms about which admittedly we don't yet know enough. It is for this reason that many scientists oppose the proposed destruction of the remaining stocks of smallpox virus. Instead of destroying this virus they argue humans would be better served if efforts were made to determine why smallpox is so successful in overcoming human defense mechanisms and why it is such a uniquely human pathogen. Highly virulent viruses with much smaller genomes like yellow fever virus or flavivirus or Ebola virus or phyllo virus or rabies virus or rabdo virus all RNA viruses they do not encode specialized proteins that function by any of the mechanisms that are just described. How do they cause their extreme pathogenic effects because these three viruses that I mentioned are extremely lethal. The functions of all the proteins that these viruses encode are noting considerable detail but they are all functions related to virus replication not with interactions with host defense mechanism components. These viruses evade host defense mechanisms by generating mutations in and around the peptides that are presented to cytotoxic T lymphocyte receptors by the MHC class 1 antigen molecules on the cell surfaces and are thus able to set up persistent infections but this is clearly not the mechanism that enables them to neutralize host defenses when they cause acute disease. There is a great deal to be discovered there. Let me make a note for doing a side here and I would like to point out that these namely the interactions between viral proteins and host cell proteins these are the interactions that shape virus evolution. Viruses are as stable as other genetic units in constant environments that is in hosts to which they have adapted maximally. This is obvious from inspection of a fresco in a tomb in the valley of the kings of an Egyptian pharaoh that clearly indicates that he had survived an infection of the same polio virus as circulates today. That is after 4,000 years and after innumerable infectious cycles the 7400 nucleotide long polio virus genome which encodes about 2,200 amino acids in the form of 12 mostly very small proteins still induces the same pathogenic effects as it did 4,000 years ago. In the same of course is true of smallpox virus which also still induces the same disease as it did in China 4,000 years ago as is evident from descriptions in ancient Chinese manuscript. Now the answer to this lies in what JD Bernal knew all along 50 years ago when he said that the key to biology and therefore also the key to evolution is protein structure. Viro genomes experience genetic changes all the time mostly but not exclusively in the form of point mutations. In RNA viruses RNA genomes owing to the absence of an error correcting function in their in their polymerases they mutate several orders of magnitude more frequently than DNA genomes as it will hear in due course from John Holland. But high mutation rates only of very limited value in the race to evolve unless the mutated protein is more efficient in doing what the parent did. High mutation rates can be they can merely add to the genetic load that is virus populations contain high proportions of particles more or less inefficient in some function. Now ability to infect a new host however or if the host itself evolves then the situation changes drastically for then viral and host cell proteins are provided with the opportunity of interacting with new partners with resultant possibility of freedom to change. Now clearly virology has been spectacularly successful in its first century. First we now have a clear picture of the genes in biogenomes. The genomes of representatives of virtually all virus families having by now been sequenced and we also know a great deal about the functions of the proteins encoded by the majority not all but the majority of these genes. Second very efficient vaccines have been developed against viruses that cause many of the major most lethal or debilitating viral diseases including influenza, measles, mumps, chicken pox, rubella, yellow fever, rabies, hepatitis A and B and rotavirus. Of course there are still viruses against which we do not yet have an effective vaccine. A major lack of success being HIV but it should of course be pointed out that we have only known about HIV for little more than a dozen years and we're still in the process of accumulating experience considering the myriad of interactions of this virus with its host namely us. No doubt Bob Gallo will deal with this in detail in his presentation. Third there's the eradication of smallpox virus the pathogen that during the course of recorded human history killed more humans than any other. A virus so specialized so well adapted to humans that we were its only host. Early in the 1920s there were still more than a hundred thousand new cases of smallpox annually in the United States and 50 years later there were none around the world. The last case having occurred in Somalia in 1979 one of the most stunning successes of modern medicine. Further polio is also about to be eradicated hopefully by the year 2000 according to some projections and it is very likely to be followed by measles virus by the year 2010. And finally of course tremendous progress has been made within the last 15 years in the area of molecular viropathogenesis that is in identifying host defense mechanism components against viral infections and of the strategies used by viruses to evade blunt and neutralize such. I should point out that research research in this area is currently extremely active in fact it is one of the hottest areas in virology and immunology. Illucidation of the functions of the proteins used by each side will assist the understanding of viropathogenesis and virulence and provide tools to study and manipulate the immune response against emerging viruses like HIV and Ebola and permit the construction of safe and effective vaccine strains against them. This is an extremely exciting area of future research which particularly for the RNA viruses as I pointed out before will end out with the yield major surprises. Now before I turn to the future let me top off the past by pointing out that the outstanding contributions of virologists have been recognized by no less than 10 Nobel Prizes and I'd just like to present those to you. In 1946 Wendell Stanley was awarded the Nobel Prize for the preparation of virus protein in pure form. In 1946 the work was actually done in the 1930s. Purification of protein then and he purified tobacco mosaic mice and crystallized it was a major achievement and in fact created in the crystallization of tobacco mosaic virus because viruses were really still regarded or can be regarded as live I mean the crystallization of a live object created great interest. Of course we should really talk about virus not as living and dead but active and inactive. Now five years later Max Tyler was awarded the Nobel Prize for yellow fever and how to combat it. In 1954 just three years later Enders Weller and Robbins were awarded the Nobel Prize for the discovery of the ability of polyvirus to grow in cultures of various types of tissues. That was the first cloning of vertebrate mammalian cells. In 1965 Jacques-Oblivoff and Monod received the Nobel Prize for the genetic control of virus synthesis and in 1966 that was a remarkable one. Peyton Rouse was awarded the Nobel Prize for tumor inducing viruses and this work was published by Peyton Rouse in 1911 55 years prior which proves that if you want to receive a Nobel Prize you've just got to stick around long enough. Three years later in 1969 Delbrook Hershey and Luria received the Nobel Prize for replication mechanisms and genetic structural viruses. In 1975 Baltimore, Dobeco and Temin received it for the interaction between tumor viruses and the genetic material of the cells that was there for the reverse transcriptase. In 1978 Arba, Nathanson Smith received it for restriction in the new phases and their application to problems in molecular genetics just like I said discovering patterns of gene expression and in 1989 Bishop and Varmus received it for the cellular origin of retroviral oncogenes and in 1993 Sharp and Roberts received it for the discovery of split genes that is the splicing of viral of messenger RNAs they demonstrated it for adenovirus messenger RNA. Okay now what about the future? There is no question that the virus replication cycles will continue to be investigated intensively however whereas in the past the emphasis the primary emphasis was on the mechanics of virus replication and the role of viral proteins in virus replication now it is likely to be replaced on the interaction of viral proteins with two classes of proteins two classes of host proteins proteins that permit promote and benefit virus replication on the one hand and proteins that limit and inhibit virus replication on the other. Of course there's also going to be a lot of activity in the field to discover new approaches to the development of agents that arrest inhibit and abort viral infections but which I'm really not going to say anything because this search is going to come from all directions and covers too many fields. It will also be on the approaches to the development of vaccines anti-viral vaccines and on the engineering of novel viral vectors with clinical applications and let me briefly go into some of these new and exciting arenas. Now first there's a group of proteins with widely varying functions that viruses subvert to creating an environment favorable for initiating and sustaining virus replication. Now many examples of such proteins are already known and more many more are constantly being discovered and will be discovered in the future. They fall into two classes those are present in cells constitutively that means they're present in cells all the time and those the expression of which is induced by viral transactivators. Let us start with the former. I need the next slide for this. There is for example the well-known case of 750 untranslated nucleotides at the 5-prime end of the picorna virus genome like polio virus the common cold and so on rhino virus. Now this region lacks open reading frames it does not encode any proteins but in spite of this in spite of its large size and the absence of open reading frames it has important regulatory functions by virtue of its ability to combine with cellular proteins at multiple sites. In fact point mutations at these sites affect the efficiency of viral protein synthesis, tissue tropism and virulence including in the case of polio virus neuro virulence and clearly the basis of all these effects lies in three dimensional structures three dimensional structure assumed by the RNA recognized by cellular proteins. I'm not going to discuss in detail the next two but then come to come to this one here and that is the genome the genomic 3-prime untranslated region and that's the other end of the RNA of and the plus strain leader sequence of measles virus as well as some other paramix viruses is bound by host proteins and the interesting thing about that is that the nature of the proteins present in cells that are permissive for measles virus replication is different from the proteins in cells that are non permissive so evidently these proteins play some major role in virus replication. The similar findings have been reported as I say for mumps para influenza virus three in vesicular stomatitis virus. Now it's also be recently been established that the RNA polymerase of vesicular stomatitis virus requires association with all three subunits of a translation elongation factor EIF1 for full activity and this is strikingly similar this is a a a mammalian virus strikingly similar to the RNA polymerase of the small single standard RNA containing cubata bacteriophage. The protein that the core polymerase encoded by the cubata genome is totally inactive when it combines with the ribosomal protein then it becomes a poly G dependent poly C polymerase in other words it just transcribes G G G G G into C C C C and it is only when it combines with two more protein synthesis factors EFTU and EFTS that it becomes a highly specific polymerase capable of transcribing and replicating cubata RNA. Okay um oh finally there's the fascinating and very interesting case of reovirus. Now reovirus messenger RNA molecules. Reovirus possesses 10 segments of RNA and so there's 10 messenger RNAs and they have a highly base paired structure resembling double standard RNA and these these messenger RNA molecules are capable of activating a protein kinase PKR that then phosphorylates the alpha subunit of another protein synthesis elongation factor EIF2 thereby inhibiting protein synthesis and limiting virus replication but it has recently been found that in cells that contain an activated RAS oncogene like cells for example that have at their surface the EGF the epidermal growth factor receptor or that express an oncogene V or B that in these cells containing an oncogene this protein kinase is not activated protein synthesis is not inhibited and reovirus replicates to high titer of course there are major implications here can reovirus be used in any way to against to destroy cancer cells because more than half of human tumors contain an activated RAS pathway signal transduction pathway. Now the second class of non-defense mechanism proteins that we like to consider and there were still proteins that benefit and then fast the virus replication sorry next slide please is this already the next slide let me have a look yes these are proteins that are activated or the synthesis of which the expression expression which is induced by viral transactivators and the most active of these transactivators are the SV40 of Popovars the SV40 large and small t antigens now large t antigen is known to induce the expression of more than a hundred genes and small t antigen induces about 25 now t antigens may influence how do how do these two antigens do this they may influence cellular gene expression by altering message RNA levels of cellular transcription factors all the various mechanisms that I'm giving you now they're actually examples in the literature of various transactivators actually doing this or they can activate they can they can alter the activity of cellular transcription transcription factors by inhibiting a phosphatase and preventing their dephosphorylation or they can interact with cellular transcription factors and thereby change their specificity they can totally replace cellular transcription factors of course they can directly bind cellular DNA and they can alter the chromosomal status of cellular DNA so it is clear it is clear that the DNA containing pox viruses herpes virus and adenoviruses and even the hepatitis B virus they all encode transcription factors that modulate the expression of many cellular genes more and more of these genes and the functions of the proteins that they encode as they affect or as they relate to the replication of the virus that induces them are now being identified and will also be fascinating of course to determine whether and to what extent and what by what mechanisms RNA containing viruses also turn out to turn out to turn on the expression of specific cellular genes now then the other class of proteins I was talking about they're the ones that inhibit the and limit the virus replication and I'm not really going to go into the into this to any extent because we've already been through the their strategies that viruses employ to counteract host defense mechanisms I'd just like to discuss one and that is the regulation of apoptosis because viruses do regulate apoptosis some viruses induce apoptosis and others inhibit the induction of apoptosis and they employ a variety of pathways for doing this a dozen or so already known and new ones are being published all the time now viruses might inhibit apoptosis because apoptosis of course destroys infected cells and so limits virus yields if you inhibit apoptosis you increase the size of virus yields and that could be obviously that is to the advantage of viruses and viruses induce apoptosis because apoptosis destroys laser cells and that leads to virus liberation so there are viruses that induce viruses that induce apoptosis do it so that deliberate progeny strange enough it appears that even the same virus under different condition can do either one or the other okay now i'd like to finish up with two highly promising aspects of the human connection of viruses and the first relates to new approaches to the development of vaccines now we have the next slide for this please thank you now there are many first of all there are a number of viruses against we badly need vaccines at this at this time and i've listed them up there take out influenza virus a influenza virus vaccine a new one the tenured virus vaccine has recently been licensed by the FDA and that looks extremely good but we certainly need a vaccine against hiv human immunodeficiency virus respiratory syncytial virus cytomegalovirus hepatitis c and e viruses and hemorrhagic fever viruses and and encephalitis that are emerging viruses they're emerging viruses because of the vastly increased mobility of human populations which brings them into much more intimate contact with the natural reservoirs of these viruses now there are many facets to the construction of viruses uh no construction of vaccines now for example one is the nature of the antigen to be used i mean should it for example be a viral peptide a viral peptide that contains the epitope the site against which neutralizing antibodies are elicited one can use just just peptides or one can use the proteins that contain these peptides that contain the epitopes vaccines against single proteins are called subunit subunit vaccines or of course one can use inactivated virus particles and finally one can also use attenuated virus strains if one decides to use the viral protein that contains the epitope against which neutralizing antibodies are elicited then uh the the the nature of the vector to be employed is of is of some importance should it be a replication competent virus like for example vaccinia virus in which case one would have to be very careful about the virulence of the viral vector um in fact i should point out that a very large number of such proteins from a lot of viruses have been cloned into vaccinia virus and if one infects with this vaccinia virus then antibodies are made against all these uh all these viruses but uh so far vaccinia virus is not favored as a vector because the it's um it is it still has residual um although it's not a dangerous viral infection nevertheless it still has some some virulence now one can also use a mammalian replication incompetent virus like for example canary pox virus canary pox virus is a bird virus it's we're not we're not uh multiplying humans and it can be used as a carrier one can even use plant viruses as a carrier but altogether i think uh one can say that uh well if the experts agree that for humans in the 21st century the virus really the virus attenuated virus vaccine strains should it would be the most uh most profitable for use now of course many vaccines already exist that that the users say attenuated the uh virus strains of course um um genus virus cow pox was was the first one of these um uh historically such virus strains are generated by passing the human pathogen through some animal host uh often developing chick embryos or the brains of suffering mice until a virus is isolated that is uh that is the same identical immunologically but has lost virulence for humans um but this technique is time consuming and um sometimes it doesn't work uh but uh for genetic engineering has now provided us with the means of improving on this method because if it is possible and there are active research going on to identify the genes that make human pathogenic viruses virulent pathogenic it should be possible to to inactivate such such genes and uh there's active work going on for example for vaccinia virus designed to to inactivate by the insertion of the irrelevant say genetic material into into the genes that cause vaccine the residual vaccine from the virulence of vaccinia virus so I think for the 21st century uh research in new ways using genetic engineering to construct vaccine strains is going to be a field of high relevance and finally I would like to just mention the rapidly emerging uh the rapidly developing potential viruses to act as key aids in the conquest against human disease now this is because their expression vectors capable of introducing genetic material into cells with high efficiency uh now I'm not going to say much of this because uh I will leave this area to Elizabeth and Gary Navel who will discuss it but I would just like to point out that let me just say that it is indeed ironic that while throughout the course of history viruses have been humanity's chief enemies they are now emerging in the second half of the 20th century as humanity's chief aids in a the provision of absolutely fundamental biological concepts and uh be in the fight against some of the most deadly diseases okay now in summary could I have the last slide please in summary the in the first century virology has proved to be the first century of virology has proved to be absolutely fascinating um the nature and structure of our genomes our genomes um I can't really our genes and elucidation it is too dark I can't read this okay uh virology has proved the key to many fundamental concepts concerning the nature structure and expression of genetic information the most deadly of human viruses smallpox virus has been eradicated and the dreaded polyamol my dreaded polyamol my lightest virus is about to be eradicated and highly efficient and effective vaccines have been developed to prevent diseases caused by many of the most severe and prevalent human pathogens uh and genetic engineering has now conferred on viruses the potential to play a vital and essential role in correcting non-viral human diseases and conditions now without without environment without without horizons widening ever more rapidly the future clearly looks fascinating and ideally wish that I could start again now I'm not sure that I would like to be a graduate student again but I'd love to be a postdoctoral fellow soaking up new ideas and concepts and using new techniques to test and explore them and one more thing I'd love to come back just for a few days in five hundred years or in a thousand years within 1500 years and so on to see how knowledge is being expanded and I'm working on doing this now I'm not now I'm not too keen on being frozen down because I really have don't have sufficient confidence that I'll be appropriately thought in five hundred and a thousand and so on years and I've been looking at the possibility of reincarnation but I've a long time ago decided if reincarnation is is a possibility I'd certainly like to come back as my wife's cat because she certainly leads the best of all possible existences but however that may be I hope that you agree with me that the first hundred years of virology have been I'll say it again absolutely fascinating and I'd no doubt that the second that the second century will be even more so thank you very much when you were here before that's where you were right the wonderful overview about wonderful thank you by far fields in the mountain out for you shaky we're ready to begin our post lecture conversation I like to before we begin that conversation though it makes some introductions the first introduction is of the first introductions are the other speakers who are at the front now and I'm going to introduce from my left to my right the first is Dr. John Holland who is the professor emeritus of biology from the University of Sandy California in San Diego next is Dr. Gary Navel who is the Henry Sewell professor of eternal of internal of eternal medicine and biological chemistry at the University of Michigan is also an investigator at the Howard Hughes Institute of Medicine and director of the Center of Gene Therapy to my immediate left is Dr. Robert Gallo who is the director of the Institute of Human Virology at the University of Maryland also a member of the Department of Microbiology Immunology and head of the tumor biology program at Baltimore Cancer Center you've already met Dr. Yoclick next is Dr. Alfred Crosby who is professor of American Studies at the University of Texas in Austin then Dr. CJ Peters who is chief of special pathogens branch of the division of viral and rickettsial diseases of the national centers of infectious diseases and the centers for disease control and prevention and finally at the right hand side is there something theological here on the right hand side is Dr. Ted Peters who is professor of systematic theology at Pacific Lutheran Theological Seminary in Berkeley California and also research professor at the Center for Theology and the Natural Sciences we are delighted all of you have accepted our invitation in the audience is a is an additional introduction is Sue Cole who is the artist of the works that are on display in the south end of the campus in the art building we can't really see in the audience from up here because of the lights but Sue would you please stand for recognition and we urge you in this evening to take a look at the paintings that she has presented the drawings the artwork the first question from the audience and actually one of my first questions for Dr. Yoclick the question is humans are no longer vaccinated against smallpox if all stocks of smallpox are not destroyed is there not a significant risk of a future smallpox pandemic and I know you have been a person that has made comments in the past about the supposed two repositories of smallpox virus well that's a very good question to start off with our our of course stocks of smallpox vaccine being maintained but that is a considerable at considerable cost my fear is that if smallpox is destroyed then these stocks of vaccine against smallpox will be let go and my fear is that there is still smallpox somewhere in some fridge or in some lab somewhere that's one fear that I have the other one is that is the existence of monkeypox virus monkeypox virus is a close relative of smallpox virus it causes a very similar disease it differs from smallpox virus in not being readily transmissible from human to human which smallpox is there have been cases of monkeypox passing on to one being passed on to one human say a nurse or a family member who looks after a patient monkeypox patient and I think there's a case a couple cases of a second transmission but that's as much there is now that is undoubtedly due to some protein or proteins in which monkeypox and smallpox differ and one doesn't know whether mutations will not increase the transmissibility of monkeypox and if that happens we've seen HIV and new acquiring a new host very recently maybe a similar change can occur with monkeypox and if the vaccinia stocks the vaccinating stocks against smallpox have been destroyed by them then we would be in serious trouble so whereas I do think that and I discussed that with CJ Peters there's a breakfast this morning we have a slight difference of opinion here but we by and large I mean we just want the best I agree that the value of smallpox at this time would be to set up a program to determine what are the how can smallpox overcome human defense mechanisms but as he quite rightly points out that requires a very expensive P4 laboratory and so on and requires funding which at the moment is not available so otherwise I mean one would just say let's keep a few ample ampoules of smallpox so that if in the future sometime occasional rises that we do want to know more about that virus it will still be available but as he quite rightly points out of course I mean smallpox virus has been sequenced and methods of synthesizing artificially DNA are rapidly progressing and I've no doubt that in within several decades it might be possible to synthesize again the genome of smallpox so it's at the moment it's a debate would you like to comment on that I think it is important to know that we have the genes available if we wanted to study the genes individually but frankly I might make a different decision than Dr. Jocleg made if I had my hand on the switch for the pressure cooker to get rid of smallpox but I don't think I would fight over the rationale either way I think the last point that Bill made is the most important one once the sequence is out of the bag once that cat's out of the bag this is really a move question I don't think it matters too much because I determined your morpher laboratory in some idiot country could probably manufacture one as you say eventually my point is just that it's easy to take a pile out of a repository and to synthesize 180,000 nucleotides questions from the from the other speakers of Dr. Jocleg her comments are observations but my my observation and my thinking is I study viruses and the strategies that they have for replication evading host defenses how have we survived all these moment yet I think by by breeding sufficiently rapidly I think a little bit lightheaded and of course one thing and until recently human populations tended to be very isolated there was very little communication among the continents and even the parts of the continent and that has certainly served to limit virus infections now with the enormous mobility a if outbreak of a of a brilliant influenza virus in Hong Kong say can be in anywhere in the United States within within 12 hours and that is a completely different situation now it's a question from the audience why have the French halted the development of the hepatitis b vaccine what do they find out take that action are you familiar with that I don't know but excuse me why to read this another question from the audience is there a limit to the number of viral types that humans can be vaccinated against can humans be over vaccinated to a point that our own immune system is weakened that's a very medically charged you could answer that best yourself couldn't you no I don't think there's any limit to the number of of of antigens against which one can be can be vaccinated one could of course if one gets too much of an antigen the antibody response might be excessive but as for the number of different antigens that will be vaccinated against I don't think there's any limit is there John you know no there there are some interesting websites maintained by people who feel that too many vaccines overwhelm our immune system particularly if they're given in a short period of time when we're young it's a little beyond the virus but just the workings of the immune system I think there are a couple of comments that are appropriate to that one is that without these vaccines and in the past when we had lower standards of hygiene most people underwent the natural infections and far more natural infections that we undergo today and certainly that's at least as much stimulus to the immune system and a lot harder on the rest of your body and the other observation is that a number of studies have been done by the U.S. military of hyper vaccinated if you will people who are working with a number of different agents and receive a number of different vaccines vaccines that are not used in the civilian population at all and that are frequently very crude vaccines in initial stages of development and no deleterious effects have been found in long-term follow-up studies of these people either can I make a comment to this recently in England I wonder whether you know about this recently in England people become concerned with the greatly increased incidence of asthma and they have related that to the possibility that in childhood now we're just too clean that we are not exposed to many of the bacterial and viral antigens to which we were exposed many years ago and that it is our exposure to these later on in life that is the absent well I don't know how that ties in but do you remember yeah I think that's mainly speculation there may be something to it you know we're also making new antigens that we've never I shouldn't say making it we're also exposed to new antigens that we've never been exposed to to this degree before and latex is a good example of that there's been an enormous amount of latex allergy in medical staff so it's complicated excuse us for our side conversation here with this the another question from the audience on the 1977 papers and virus replication and the Nobel conference none of us are on the none of you not me and definitely but none of you are on the selection committees for the Nobel Prize selection the question that was asked from the audience is why did rich roberts and the other and and sharp received the Nobel Prize but none of the other co-authors of their works did or the co-authors listed in order of prominence or in reverse order of prominence so i was going to let the the research scientists take a deal with that but dr gallo had a response for that so we can take a guess i think that the awards are usually for a body of work not one particular paper and are generally selected to lab leaders the nobel decisions i think are to limit the number of people who can get it otherwise everyone would get one because but i think they selected lab leaders for a significant body of work and then pointed out some special papers in that body of work at least i would be my best guess authorship in biological papers is generally the that the senior author is listed last and as bob says the senior author has most experience the prize is as he says for a body of work the senior author provides the ideas the stimuli stimulus and directs the work so in this particular case it's the two senior authors who received the nobel prize but i agree with the question there has been considerable controversy in the past in several cases of why more junior workers were not included in the nobel prize as i say this is just the custom it may change changing the subject at the end of toward the end of your talk you briefly mentioned the dna vaccines at least it was at the bottom of the slide what do you see of the future of the dna vaccines in which the genetic information is injected rather than the protein that directly stimulates the immune response yes i didn't feel i had time to really discuss this i know the people who are responsible this very well this works of course for for dna containing viruses and also for RNA containing viruses because all one does then is to reverse transcribe the RNA in a dna and inject that dna and then it simply is that that that is of course an extremely interesting discovery if you'd asked me before and i would have never thought that this would work because i would have thought that the that the dna would be the free naked dna would be broken down and most cells are not adapted to taking up dna but it what happens is that the dna is taken up and transcribed by cellular enzyme and then of course the protein synthesizing mechanism in in cells translates that into the protein which then acts as antigens certainly the results are extremely favorable it remains to be seen now whether these these dna containing dna vaccines can be adapted to clinical use do you know that whether anything is about clinical trials up with is human they already being i think dr. navel yeah there there are clinical trials that are ongoing with the dna vaccines there are several hopeful results so i i i think the my read on the the data as i see it in in meetings right now is that there are encouraging results it seems to be reasonably effective at providing t-cell particularly cytotoxic t-cell immunity although it may not be sufficiently robust yet by itself to be efficacious as a vaccine it's still early days but i think if one were to guess that we either need to enhance the systems using some of the approaches you mentioned with cytokines or perhaps combining them with more traditional vaccines then the two together may work better than either one alone well i think our panels for this morning's discussion dr. jockelic for his broad perspective of the world of viruses we will adjourn now until 1 30 for the lecture given by dr. holland