Characterization of low titer influenza subtype H3 viruses HA1 from children in Beijing the winter of 2004

Objective To investigate HA1 hemagglutinin variant of influenza viruses isolated from children with influenza-like-illness (ILI) patients in Beijing in the 2004—2005 season and all viruses were subtype H3 at low titer of HA.Methods RNA of the 22 strains of influenza A type (H3) from the ILI children was extracted, HA1 fragment of hemagglutinin (HA) gene was amplified by RT-PCR and analyzed by bioinformatic softwares.Results 987 bps of HA1 coding 329 amino acid, which 22 strains influenza A type (H3 subtype)...