Tips from the Journals of the American Society for Microbiology

New Vaccine That Protects Monkeys Against Avian Flu Ready for Human Trials

Researchers from the National Institutes of Health and University of Maryland report that a new vaccine that protects monkeys against the avian influenza virus is now a candidate for clinical trial in humans. They report their findings in the November 2007 issue of the Journal of Virology.

The rate of transmission of the highly pathogenic avian influenza virus (HPAIV) from birds to humans is rapidly increasing. The H5N1 strain is responsible for 278 known human infections resulting in 168 deaths. The possibility of a pandemic outbreak emphasizes the need for an effective vaccine, however development has been impeded by factors such as poor immunogenicity, biosafety concerns, and risk of genetic exchange with circulating influenza virus strains.

In the study researchers developed a live vaccine incorporating the avian Newcastle disease virus (NDV), which expresses a common gene found in the H5N1 avian influenza virus, and tested it in African monkeys. The vaccine was administered both intranasally and through the respiratory tract in two doses with a 28-day interval in between. Response after one dose showed low amounts of virus shedding indicating protection. Following two doses, high levels of neutralizing antibodies were present in all immunized monkeys. A substantial response to either dosage was noted in the respiratory tract indicating a likely reduction in transmission in the event of an outbreak.

“In this study, we have developed a vaccine candidate, NDV-HA, for immunization against H5N1 HPAIV and have tested it in a nonhuman primate model,” say the researchers. “The vaccine was well tolerated and induced substantial local and systemic immune responses, demonstrating that NDV has potential as a live virus candidate vaccine against HPAIV.”

(J.M. DiNapoli, L. Yang, A. Suguitan Jr., S. Elankumaran, D.W. Dorward, B.R. Murphy, S.K. Samal, P.L. Collins, A. Bukreyev. 2007. Immunization of primates with a Newcastle disease virus-vectored vaccine via the respiratory tract induces a high titer of serum neutralizing antibodies against highly pathogenic avian influenza virus. Journal of Virology, 81. 21: 11560-11568.)

Researchers Identify a Promising New Class of Inhibitors Against West Nile Virus

Researchers from the Washington University School of Medicine have identified a new class of compounds that may inhibit West Nile virus in humans. They report their findings in the November 2007 issue of the Journal of Virology.

West Nile virus (WNV), a member of the flavivirus family which also includes dengue virus and yellow fever virus, can cause disease in humans, horses, and other vertebrate species when transmitted by infected mosquitoes. WNV has been confirmed in all 48 continental United States as well as Canada, Mexico, the Caribbean and South America and the fatality-to-case ratio calculated from recent outbreaks is 4 to 14%. There were 24,000 human cases diagnosed between 1999 and 2006 and currently there is no vaccine or therapeutic treatment approved for use in humans.