H9N2亚型禽流感病毒对海兰白鸡感染和传播特性的研究

Study on Characteristics of Infection and Transmission of H9N2 Subtype Avian Influenza Virus in Hy-Line White Chickens

为研究H9N2亚型禽流感病毒（AIV）对海兰白鸡的感染和传播特性,将80只4周龄海兰白鸡随机分为8组,每组10只,其中感染组5只,同居组5只,采用100～107EID50/0.4 mLH9N2 AIV以滴鼻和点眼方式攻毒,24 h后放入同居组。感染14 d内每天进行临床观察,采集咽拭子和泄殖腔拭子用于病毒分离,感染后7、10、14 d测定HI抗体滴度。结果表明：4周龄海兰白鸡感染H9N2 AIV后未出现明显的临床症状;感染剂量为10^0～10^1 EID50/0.4 mL的感染组和同居组均未分离到病毒;感染剂量为10^2～10^3 EID50/0.4 mL的感染组排毒期为2～6 d,同居组排毒期为4～6 d;感染剂量为10^4～10^7 EID50/0.4 mL感染组排毒期为1～6 d,同居组排毒期为2～8 d;感染剂量为10^2～10^7 EID50/0.4 mL感染组和同居组鸡分别于感染后7和10 d开始产生抗体,第14天感染组和同居组鸡的平均抗体滴度分别为（7.8±1.4）log2和（6.7±1.1）log2。结果显示该毒株使4周龄海兰白鸡全部感染的最低感染剂量为103EID50/0.4 mL,以106EID50/0.4 mL感染鸡,能刺激感染组与同居组产生较高的HI抗体,表明106EID50/0.4 mL H9N2亚型AIV能在海兰白鸡体内建立有效感染和传播。

To study the characteristics of infection and transmission of H9N2 subtype avian influenza virus（AIV）in Hy-Line white chickens,80 4-week-age Hy-Line white chickens were randomly divided into eight groups with five for infected group and five for contact group. The viruses were used to inoculated intranasally and intraocularly with different doses from 100 to 107EID50/0.4 mL and five contact chickens were added after 24 hours. During 14 days post infection,clinical observation was conducted on a daily basis,tracheal and cloacal swabs were taken for virus isolation,blood samples were taken at the 7th,10 th,14th day after infection for HI antibody detection. The results showed that there were no major clinical symptoms in 4-week-age Hy-Line white chickens infected with H9N2 AIV. It was negative in infected and contact groups with the dose of 10^0 to 10^1 EID50/0.4 mL. The virus shedding time of H9N2 AIV was2 to 6 days and 4 to 6 days with the dose of 10^2 to 10^3 EID50/0.4 mL in infected and contact groups respectively,but it was 1 to 6 days and 2 to 8 days with the dose of 10^4 to 10^7 EID50/0.4 mL,respectively. It began to produce HI antibody at the 7th day and 10 th day after infection in infected and contact groups with the dose of 10^2 to 10^7 EID50/0.4 mL.At 14 th day,the average HI antibody titers in infected and contact Hy-Line white chickens were（7.8±1.4）log2and（6.7±1.1）log2. The results showed that all chickens were infected by H9N2 AIV with the lowest dose of 103EID50/0.4 mL,and it could produce the higher HI antibody titers in infected and contact groups with the dose of 106EID50/0.4 mL.So Hy-Line white chickens could be infected with H9N2 AIV and transmit from infected birds to contacting birds effectively with the dose of 106EID50/0.4mL.