Analysis on pathogen and hemagglutinin genetic variation of influenza viruses in Inner Mongolia in 2009

OBJECTIVE To explore the type and subtype distribution of influenza viruses in influenza-like patients and the hemagglutinin (HA) genetic variation of influenza A viruses in Inner Mongolia during the influenza prevalent season in 2009. METHODS Oropharyngeal swabs were collected from the influenza-like patients in the sentinel hospitals and during the out-breaks, and then identified by real-time reverse transcription-polymerase chain reaction ( RT-PCR) , positive specimens were subsequently inoculated into embryonated egg to isolate influenza viruses. HA segments of influenza A viruses were sequenced to analyze the genetic variation of HA. RESULTS 419 positive specimens were detected with real-time PCR, including 182 (43.44%) influenza A / H1N1. 162 isolates of influenza viruses were collected from 419 positive specimens, the isolation rate being 38.66%. Of these influenza viruses isolated, 155 (95.68%) were influenza A / H1N1 2009, 2 had a mix of influenza A / H1N1 and H3N2, 4 were H3N2 and 1 was influenza B. HA sequences data showed that the virus had the high homeology with reference virus. CONCLUSION Influenza A / H1N1 is main predominant virus subtype in 2009 in Inner Mongolia. It is similar with the vaccine-like virus and the isolated virus of China.