To elucidate the antigenic drift and evolution of h9n2 subtype avian influenza viruses ( aivs ) , five isolates from the north of henan province during 1998 - 2002 were compared and analysed by cross - hemagglutinin inhibition test ( hi ) , cross - virus neutralization test ( vn ) in the chicken embryo and chicken embryo primary kidney cell ( cek ) and cross protection against challenge infection test 為了探討h _ 9n _ 2亞型禽流感病毒的抗原性有否發(fā)生漂移,本研究從生物學角度和ha基因分子水平上對1998 ? 2002年間在河南省豫北地區(qū)分離到的5株h _ 9n _ 2亞型禽流感病毒的抗原性變化進行了比較和分析。