[1] Bogner Org, Santa Monica, CA 90403 USA
[2] Ist Zooprofilatt Sperimentale Venezie, OFFLU OIE FAO Network, Sci Comm, I-35020 Padua, Italy
[3] Ctr Dis Control & Prevent, Influenza Div, Atlanta, GA 30333 USA
[4] NIH, Natl Ctr Biotechnol Informat, Bethesda, MD 20894 USA