Objective To study the genetic information in HA genes and antigen specificities of SWSS1, SWL6 and Pdm091057 strains which respectively belongs to Eurasian avaian-like, classical and Pdm09H1N1 branches of H1N1 swine influenza viruses (SIV), and provide a basis for functional study on antigenic epitopes of HA gene as well as prevention and control of influenza virus.
Method We compared the genetic information in HA gene fragments of three H1N1 subtypes, SWSS1, SWL6 and Pdm091057. Inactivated SIV vaccines were prepared and each type of vaccine was used to immune three New Zealand white rabbit. The hemagglutination inhibition (HI) reaction was used to detect antibody titers.
Result The amino acid sequences of HA gene fragments had 69.4%–89.1% similarities among three SIV strains. There were variations in antigenic epitopes ofHA genes of the three strains. The average HI antibody titers were all above 1 280 for three strains after the second immunization, and the average HI antibody titer for SWSS1 reached 2 560. SWSS1 had no serological cross reaction with SWL6 or Pdm091057 strain, while SWL6 and Pdm091057 strains had low degree of serological cross reaction.
Conclusion Three SIV strains have differences in antigenic epitopes of HA gene, which may be the reason for the low degree of serological cross reaction among strains. All three strains have good immunogenicity, and can be used as candidate vaccine strains.
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