封闭式饲养鸡场H9N2亚型禽流感病毒HA基因在5年内的遗传变异

选择一个于1998年开始发生H9亚型禽流感的封闭式大型养鸡场，连续5年内分离到22株H9N2亚型病毒，对其中9株与1998年分离株进行HA基因序列和病毒抗原性的比较结果表明，这些分离株均与1998年的具有较高的序列同源性，且在本研究期内HA基因的这些变化尚未产生引起交叉保护性改变。初步推断这些分离株均系1998年分离株在场内循环传播变化得来，其HA基因的变异可能与频繁的疫苗免疫选择压力有关。这为进一步研究禽流感病毒变异的规律和制定正确的禽流感防治对策具有重要意义。

Genetic Mutations of Heamagglutinin Genes of H9N2 Subtype Influenza A Viruses in the Field in a Five-year Period

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.