[Genetic mutations of heamagglutinin genes of H9N2 subtype influenza A viruses in the field in a five-year period]

Abstract

Infection in chicken flocks on a farm, where AI outbreak took place in 1998, was monitored in a four-year consecutive period and 22 H9N2 subtype viruses were isolated. The HA gene and antigenicity of 9 strains among isolates were compared with that of isolate of 1998. The results indicated that mutations of HA genes of H9 subtype influenza A viruses were observed during five years. However these mutations of HA genes didn't lead to sufficient antigenic variation to change the cross-protective pattern of these strains. These findings may be fruitful for making further study of genetic mutations of AIVs in the field and improving the control strategies.