Serological surveillance of swine influenza in different regions of China from 2011 to 2012

To investigate the prevalence of swine influenza virus(SIV) in China,serological surveillance of SIV was conducted in different regions from 2011 to 2012.A total of 13,044 pig serum samples were collected from slaughterhouse,large-scale pig farms and individual farms.These samples were tested by the HI test for antibody detection of the classic swine H1,Eurasian avian-like H1,2009 H1N1 pandemic virus,H3 subtype virus,avian H5 and H9 subtype virus.Serological tests showed that the positive rates and geometric mean antibody titer(GMT) of classic swine H1,the Eurasian avian-like H1 and Pandemic H1N1 2009 were higher than other SIV subtypes.In addition,Eurasian avian-like H1 positive were slightly increased from 42.24% to 45.89% during 2011 to 2012.While,the GMT pandemic H1N1 2009 and classic swine H1 were 53.32 and 73.2 which were highest in 2011 and 2012,respectively.The results indicated that H1N1 subtype SIV infection is predominated subtype in China during 2011 to 2012.