H9N2亚型禽流感流行株灭活疫苗种毒的筛选

Selection and evaluation of H9N2 avian influenza inactivate vaccine candidates

为筛选出具有良好免疫原性的禽流感病毒(AIV)H9N2亚型灭活流行株种毒,选择2008年中国大陆8个省份15株H9N2亚型AIV分离株进行抗原性分析,选取代表流行株进行鉴定并制备灭活疫苗,进行免疫效力评估。实验结果显示,2008年分离株之间抗原性比较接近,与2000年前分离株的抗原性相差较大;2008年分离的8株病毒HA基因核苷酸同源率在93.2%～98.6%之间,而CK/SH/10/01毒株与这8株病毒的同源率仅在91.9%～93.5%之间;CK/ZJ/17/08、CK/SD/2CZ/08、DK/FJ/560/08、CK/FJ/521/08、CK/HuN/174/08和CK/HuN/33/08候选株病毒在SPF鸡胚上连续传15代HA价及致病性等均未改变,SPF鸡鼻腔感染106EID50各毒株后均无任何症状和死亡出现;候选株灭活疫苗免疫SPF鸡3周时,产生针对疫苗株抗原检测的HI抗体介于10.35log2～11.811log2,以106EID50剂量鼻腔感染途径攻毒后,只有CK/HuN/174/08和CK/HuN/33/08株灭活疫苗免疫鸡不仅可以对同源毒株的攻击提供良好的免疫保护,而且对2008年分离的异源毒株的攻击也能提供比较理想的免疫保护,可作为适合我国大部分地区应用的H9N2亚型禽流感灭活疫苗种毒株。

In this study,candidate vaccine strains were selected from fifteen H9N2 subtype avian influenza viruses（AIV） isolated from eight provinces in China's Mainland during 2008. Six vaccine strains including CK/ZJ/17/08,CK/SD/2CZ/08,DK/FJ/560/08,CK/FJ/521/08,CK/HuN/174/08 and CK/HuN/33/08 were selected based on the antigenic analysis. The immune efficacy of the strains was evaluated by inoculaing SPF chickens with oil-emulsion inactivated vaccines prepared from respective strains. The results showed that all vaccine strains could induce high level（10.35 to 11.81 log2） hemagglutination inhibition antibody against homologous H9N2 virus at 3 weeks post-immunization,and the CK/HuN/174/08 and CK/HuN/33/08 inactivated vaccines were shown to protect the SPF chickens from challenge by both homologous and heterologous AIV H9N2 strain. The results indicated that only CK/HuN/174/08 and CK/HuN/33/08,but not all the H9N2 strains,have the potential attributes to be qualified as inactivated vaccine candidates against H9N2 virus in most parts of China's Mainland.