1. Jiangsu CDC-Nanjing University Joint Institute of Virology, Jiangsu Center for Disease Control and Pevention, Nanjing 210009, China 2. China Animal Health and Epidemiology Center, Qingdao 266032, China
One influenza H3N2 virus, A/swine/Shandong/3/2005 (Sw/SD/3/2005), was isolated from pigs with respiratory disease on a farm in eastern China. Genetic analysis revealed that Sw/SD/3/2005 was a triple-reassortant virus with a PB2 gene from human-like H1N1, NS from classical swine H1N1, and the remaining genes from human-like H3N2 virus. These findings further support the concept that swine can serve as reservoir or mixing vessels of influenza virus strains and maintain genetic and antigenic stability of viruses. Furthermore, we have successfully established a reverse genetics system based on eight plasmids and rescued Sw/SD/3/2005 through cell transfection. HI tests and RT-PCR confirmed that the rescued virus maintained the biological properties of the wild type Sw/SD/3/2005. The successful establishment of the reverse genetics system of Sw/SD/3/2005 will enable us to conduct extensive studies of the molecular evolution of H3N2 influenza viruses in swine.