H9亚型禽流感重组鸡痘病毒疫苗的免疫保护试验

IMMUNITY OF CHICKENS INDUCED BY RECOMBINANT FOWLPOX VIRUS EXPRESSING HA GENE OF AN H9-AIV

应用表达H9亚型禽流感病毒(AIV)血凝素(HA)基因的重组鸡痘病毒疫苗及其传代后第20、30代疫苗免疫5日龄无特定病原(SPF)鸡群,于免疫后采血测定HI抗体效价,并于免疫后第21天攻毒,攻毒后2～13d进行泄殖腔棉拭子采样,接种鸡胚测排毒情况。各免疫组在免疫后7～20d的HI抗体效价逐渐上升,但不同剂量组间、不同传代代次间有差异;攻毒后第5天各免疫组排毒的鸡数与对照组相比显著减少,且不同攻毒毒株组间无差异。重组苗组在攻毒后第2天仅有8%排毒,第5天则无排毒;灭活油苗组在攻毒后第2、5、7天分别有52%、12%、4%排毒,直到第9天才不排毒;空白攻毒组在攻毒后2～13d排毒率由92%缓慢降至8%。结果表明:研制的表达H9亚型禽流感病毒HA基因的重组鸡痘病毒载体疫苗具有较高的免疫保护效力,不低于灭活油苗,且在抑制早期排毒、防止群内传播方面优于灭活油苗。

To evaluate its protective efficacy against H9subtype avian influenza virus (AIV), a recombinant fowlpox virus (rFPV) containing H9subtype AIV hemagglutinin (HA) gene and its 20th, 30th passages were administered to specificpathogenfree (SPF) chickens at 5 days of age. All chickens were divided into 8 groups according to dosage, passage and challenge strain of virus and challenged three weeks later. Even though the mean hemagglutinationinhibition antibody titer of each rFPVvaccinated group is lower than that of inactivated oil vaccine group before challenge and with difference among them, almost all rFPVvaccinated groups had near or more than 90% protection from virus shedding by cloacal swabbing as oil vaccine group had at 5 days post challenge, and there was no difference among them. These findings demonstrated that this recombinant fowlpox vaccine virus could provide enough protection against H9subtype avian influenza viruses and had the advantage of inhibiting virusshedding more quickly.