Development and application of avian influenza vaccines in China.

Following the first detection of the highly pathogenic H5N1 avian influenza virus in sick geese in Guangdong Province in China in 1996, scientists began to develop vaccines in preparation for an avian influenza pandemic. An inactivated H5N2 vaccine was produced from a low pathogenic virus, A/turkey/England/N-28/73, and was used for buffer zone vaccination during H5N1 outbreaks in 2004 in China. We also generated a low pathogenic H5N1 reassortant virus (Re-1) that derives its HA and NA genes from the GS/GD/96 virus and six internal genes from the high-growth A/Puerto Rico/8/34 (PR8) virus using plasmid-based reverse genetics. The inactivated vaccine derived from the Re-1 strain could induce more than ten months of protective immunity in chickens after one-dose inoculation; most importantly, this vaccine is immunogenic for geese and ducks. We recently developed a Newcastle virus-vectored live vaccine that exhibits great promise for use in the field to prevent highly pathogenic avian influenza and Newcastle disease in chickens. Over 30 billion doses of these vaccines have been used in China and other countries, including Vietnam, Mongolia, and Egypt, and have played an important role in H5N1 avian influenza control in these countries.