ARS | Publication request: PATHOGENESIS OF HIGHLY VIRULENT AVIAN INFLUENZA A VIRUSES IN MICE AND PROTECTION BY VACCINATION WITH BACULOVIRUS-EXPRESSED HEMAGGLUTININS

Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 20, 1999
Publication Date: N/A

Technical Abstract: In 1997, highly virulent H5N1 avian influenza viruses were directly linked to 6 human deaths. It is important to understand factors promoting this transmission to mammals and to prevent further outbreaks. Several highly virulent H5 avian influenza A viruses from Eurasia and North America were analyzed for their ability to cause pathology, disease and death in 6 to 8- -week-old BALB/c mice. The AI isolates from the Hong Kong outbreak caused severe pneumonia, rapid decrease in body temperature and mortality within 6 to 8 days pi. Prior vaccination with baculovirus-vectored HA proteins from HK strains prevented all clinical signs of disease in the HK virus-infected mice. Only A/tk/England/91 caused significantly decreased body weights and temperature at 4 dpi; however, no deaths occurred and mice recovered quickly from infection. This isolate may thus represent an intermediate in the evolution to virulence in mammals. Genetic determinants of mammalian pathogenicity are being studied by mating virulent H5N2 isolates that exhibit no pathology or disease in mice with the HK viruses. The chicken- lethal Mexican isolate A/ck/Queretaro/20/95 was successfully mated with the HK isolate A/ck/HK/220/97 to help identify genes specifying the mouse- virulent phenotype.