3株H9亚型禽流感病毒的分离与鉴定

为了获得H9亚型禽流感病毒(AIV)流行毒株并掌握流行毒株的分子特征和致病性,采用病毒分离、血凝性试验、鸡胚半数感染量(EID₅₀)测定、HA基因序列分析、致病性试验、交叉保护性试验等对3份临床疑似H9亚型AIV感染病料进行了研究。结果:3份临床病料样品可引起10日龄SPF鸡胚规律性死亡,3株分离毒株对1%鸡红细胞的凝集效价分别10log₂、11log₂和10log₂;对SPF鸡胚的EID₅₀分别为10^-8.83/mL、10^-9.50/mL和10^-9.0/mL;与2018年上海分离毒株亲缘关系较近,进化树处于同一分支;对SPF雏鸡的发病率分别为80%、100%和90%;均未引起SPF雏鸡死亡;彼此之间具有100%的交叉保护率,商品化禽流感(H9亚型)灭活疫苗对3株分离毒株的保护率分别为100%、90%和100%。本试验成功分离鉴定到了3株低致病性H9亚型AIV流行毒株,并证实当前商品化疫苗对H9亚型AIV流行毒株仍具有较好的保护效果。

Isolation and identification of three strains of H9 subtype avian influenza viruses

In order to obtain the H9 subtype AIV epidemic strain and identify its molecular characteristics and pathogenicity,three clinically suspected H9 subtype AIV infectious materials were studied by virus isolation,hemagglutination test,EID50 assay,HA gene sequence analysis,pathogenicity test and cross protection test.The results showed that the three clinical samples could cause regular death of 10 day old SPF chicken embryos.The agglutination titers of the three strains to 1%chicken red blood cells were 10 log₂,11 log₂ and 10 log₂,respectively.Their EID50 the SPF chicken embryos were 10-8.83/mL,10^-9.50/mL and 10^-9.0/mL,respectively.The three strains were closely related to the isolates from Shanghai in 2018,and their evolutionary trees were in the same branch.The incidence rate of the three strains of SPF isolates was 80%,100%and 90%respectively,but the strains did not cause SPF chickens to die.They had 100%cross protection rates,and the protective rate of commercial avian influenza(H9 subtype)inactivated vaccine against three strains were 100%,90%and 100%,respectively.Therefor,three strains of AIV H9 subtype with low pathogenicity were successfully isolated and identified,and the current commercial vaccine still had a good protective effect on the AIV H9 subtype.