Gene Therapy (2001) 8, (Suppl 1), S1–S13 2001 Nature Publishing Group All rights reserved 0969-7128/01 $15.00 www.nature.com/gt QUASISPECIES AND VIRUS EVOLUTION PANDEMIC SPREAD: INFLUENZA Robert G. Webster1•2, Yi Guan2, Scott Krauss1, Kennedy Esteban Domingo Shortridge2, Malik Peiris2 Centro de Biologfa Molecular "Severo Ochoa" 1) Dept. Virol Mo! Biol, St. Jude C R Hosp., 332 N. (CSIC-UAM). Cantoblanco, 28049 Madrid, Spain Lauderdale, Memphis, Tennessee, and 2) Dept Microbiol, Hong Kong Univ., SAR China High mutation rates and quasispecies dynamics are a Influenza virus continues to evolve, and new antigenic drift hallmark of RNA viruses. Recent studies with foot-and­ variants emerge constantly, giving rise to yearly epidemics. In mouth disease virus (FMDV) have revealed rapid addition, strains to which most humans have no immunity coevolution of antigenicity and host cell tropism of virus appear suddenly, and the resulting pandemics vary from populations in cell culture and in vivo. Remarkable serious to catastrophic. Studies in aquatic birds over 25 years expansions of host cell tropism occurred in a clonal have established that they play an important role in the natural population of FMDV as a result of prolonged cytolytic history of influenza viruses. In the past four years there have replication in BHK-21 cells. Reversion of mutants with been two different transmissions of avian influenza viruses to humans in Hong Kong. The first genetic lesions associated with decreases in viral fitness, occurred in 1997, when 6 of 18 infected humans died of H5Nl influenza virus. In March and analysis of the mutant spectra of revertant 1999, H9N2 influenza viruses were isolated from two children populations, have indicated the presence of memory in Hong Kong and unconfirmed reports of an additional five genomes in viral quasispecies. Memory can be durable cases have been reported from Southern China. The re­ and memory levels are fitness-dependent. Use of FMDV emergence of H5Nl influenza viruses in poultry markets in mutants covering a 106 - fold range in relative fitness 2001 resulted in slaughter of all of the poultry in Hong Kong values has permitted progress in understanding the and re-evaluation of the role of poultry markets as the site for mechanisms of viral extinction by accumulation of reassortment of influenza viruses. Although no human cases mutations and by enhanced mutagenesis (virus entry into of H5Nl were detected in 2001 the presence of multiple error catastrophe). These observations may find reassortants containing gene segments related to HSNl/97 application in improved diagnostic procedures and in the influenza viruses was of great concern. Sooner or later these viruses will acquire development of new antiviral strategies. the ability for human to human transmission and it is urgent to be able to detect such viruses as early as possible. The long-term goal is to define the molecular markers of such transmission. Protection from SIV vaginal challenge using Sabin poliovirus EMERGENCE OF NIP AH VIRUS. SherifR. Zaki, M.D., Ph.D. vectors. S. Crotty, CJ. Millel", B.L. Lohman~ M. Neagu, L. Compton#, Centers for Disease Control & Prevention, 1600 Clifton Rd., N.E., D. Lu#, F. X.-S. LO#, L. Frittl, J.D. Lifson , and R. Andino•. Dept MS-G32, Atlanta GA 30333 Microbiology & Immunology, UCSF; #California Regional Primate Research Center, Dept Pathology, UCD; "Depts Pathology, Microbiology, & Immunology, School of Veterinary Medicine, and An outbreak of severe febrile encephalitis associated with high Center for Comparative Medicine, UCD;® Retroviral Pathogenesis mortality rates was reported in Peninsular Malaysia beginning in Laboratory, AIDS Vaccine Program, SAIC Frederick, Frederick, MD. late September 1998. By mid-June 1999, more than 265 The Sabin live poliovirus vaccine is one of the best human vaccines. It encephalitis cases, including l OS deaths, had been reported in produces long lasting immunity and herd immunity; it is easy to Malaysia, and 11 cases of encephalitis or respiratory illness with experimentally manipulate; it has a proven safety and efficacy record in one death had been reported in Singapore. Pathologic, electron over I billion vaccines; it is cheap to produce and distribute; and most importantly, it produces a potent mucosa! immune microscopic, serologic, and genetic studies indicate that this virus, response. These beneficial characteristics have provided the bases for the optimism on the now known as Nipah virus, belongs to the family Paramyxoviridae current efforts for the poliovirus eradication program. The WHO wild and is most closely related to the recently discovered Hendra virus. poliovirus eradication effort has been very successful, and we are Hendra and Nipah viruses are likely representatives of a new genus hopeful that wi ld poliovirus infections can be eliminated. In the other within the family Paramyxoviridae. hand, with respect to AIDS vaccine, the capacity of poliovirus to Like Hendra virus, Nipah virus is unusual among the generate a strong mucosa! immune response is particularly important given that greater than 90% of HIV-I infections worldwide have been paramyxoviruses as it exhibits an extended host range, with natural sexually transmitted. Any strategy to control the AIDS pandemic must and experimental infections and fatal cases occurring in swine, include a vaccine that prevents sexual transmission of HIV-I. We have humans, cats, and dogs. The emergence of this disease can be developed a live poliovirus based vaccine vector system, making it attributed to a number of factors including environmental factors, possible to insert gene fragments derived from various pathogens into the animal husbandry and deforestation. Recent studies including viral full poliovirus genome. This vaccine vector system is able to stimulate potent immune responses directed against desired isolation have implicated fruit bats as a possible reservoir for viral pathogens both in mice and primates. Now we generated a series of new Sabin-SIV viruses Nipah virus. containing SIV gag, pol, env, nef, and tat in overlapping fragments. Nipah virus infection is a newly recognized disease, with a These Sabin-SIV recombinants were then inoculated into seven spectrum of microscopic morphological changes involving the macaques as a candidate S I V vaccine. All monkeys made substantial CNS in humans and the respiratory system in pigs. Widespread anti-SIV serum and mucosa! immune responses. Vaccinated macaques, and twelv endothelial cell infection, vasculitis, and CNS parenchymal cell e control macaques, were challenged vaginally with pathogenic SIV mac25 I. Strikingly, 4 of 7 vaccinated animals exhibited substantial infection play an essential role in the fatal outcome of infection in protection against the vaginal SJV challenge. In two of the seven SabRV­ humans and appear to be central to the pathogenesis of this SIV vaccinated monkeys we found no virological evidence of SIV emerging infectious disease. infection following challenge, indicating that these two monkeys were completely protected. Three of 6 control animals developed clinical AIDS by 48 weeks post-challenge. In contrast, all 7 vaccinated monkeys remain healthy as judged by all clinical parameters. These results demonstrate the efficacy of SabRV as a potential human vaccine vector. Abstracts S2 THE CORRELATES OF PROTECTIVE IMMUNITY MEASLES VACCINES-ISSUES OLD AND NEW. D. Griffin, F. AGAINST HIV AS DETERMINED BY PASSIVE Polack, H. Robinson, A. Valsamakis, S. Hoffman. W. Harry IMMUNIZATION WITH HUMAN NEUTRALIZING Feinstone Dept of Molecular Microbiology & Immunology, Johns MONOCLONAL ANTIBODIES IN PRIMATES Hopkins Bloomberg School of Public Health, Baltimore, MD The Edmonston strain of measles virus (MV), isolated in 1954 by Flavia Ferrantelli1.2, Weidong Xu' ·2, Regina Hofmann-Lehmann 1•2, John Enders, is the source of most of the current measles vaccine Pei-Lin Li u, Lisa Ca vacini'-3, Marshall Posner2·3, Hermann Katinger4 strains. Wild type MV was attenuated primarily by multiple Gabriela Stiegler4 , Harold McClure5 and Ruth M. Ruprecht '· 2 passages in tissue culture, mainly chicken cells, a host that is not normally susceptible to MV infection. The molecular basis of 'Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, attenuation is not fully understood, but sequence changes exist 2 3 throughout the genome, most notably in the genes for the Harvard Medical School, Beth Israel Deaconess Medical Center, hemagglutinin (H) surface glycoprotein and the large polymerase 4Institute of Applied Microbiology, Vienna, Austria and 5Yerkes protein. Normal sites of MV replication are endothelial cells, Regional Primate Research Center, Emory University, Atlanta, GA epithelial cells and monocytes and the vaccine is assumed to have similar target cells, but to replicate and spread less efficiently in Passive immunization with synergistic combinations of humans (approximately 5% of immunized infants develop a rash). The primary problem human monoclonal antibodies with this otherwise safe and effective (mAbs) directed against vaccine is the inability to immunize young infants, due in large conserved epitopes of the HIV envelope completely protected part to interference with virus replication by maternal antibody. In 13 out of 16 rhesus monkeys challenged intravenously or orally developing countries measles often occurs prior to the age of with chimeric simian-human immunodeficiency virus (SHIV) routine immunization (9-15 mos) and 1/3 of the 1 million