title: [The feature of influenza virus activity and genetic characterization of HA1 gene of influenza A H3N2 viruses isolated from 1994-1997 in Shenzhen].
abstract: OBJECTIVE
  To understand the feature of influenza virus activity and genetic characterization of HA1 gene of influenza A H3N2 viruses isolated in recently years in Shenzhen.
  
  
  METHODS
  The specimens were inoculated into amniotic and allantoic cavities of the embryonated chicken eggs for viral isolation. The isolates were typed with HI test. Virion RNA extracted from allantoic fluid by Rneasy RNA extraction kit was used for RT-PCR amplification. Afterward, the product of PCR was purified with purification kit. RNA sequence analysis was performed by Sanger dideoxy-mediated nucleotide chain termination method.
  
  
  RESULTS
  Influenza A H3N2, H1N1 and B viruses were cocirculating in men in Shenzhen in recent years. However, the extent of their activities was not the same in a single year. The influenza B virus was the predominant strain in 1994 and 1997, but the predominant strain was H3N2 virus in 1996. The genetic analysis showed that the substitution of amino acids occured year by year and was mainly located at antigenic determinants or receptor binding site on HA1 domain of H3N2 viruses.
  
  
  CONCLUSIONS
  Influenza A H3N2, H1N1 and B viruses were still co-circulating in men in Shenzhen in recent years, the predominant strain of influenza virus was different in different years. An increase of influenza A H3N2 virus activity in 1996 was due to the substitution of amino acids sequences on viral HA1 domain.
authors.forename: X
authors.initials: X
authors.lastname: Cheng
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: He
mesh_terms: D000595:Amino Acid Sequence; D005260:Female; D005814:Genes, Viral; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype; D009980:Influenza A virus / Q000145:classification / Q000235:genetics*; D009981:Influenza B virus / Q000145:classification / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000235:genetics
chemical_list: D012367:RNA, Viral