Re-8株H5亚型禽流感灭活疫苗对野鸟源H5N8流感病毒的免疫保护性研究

Protection efficacy of Re-8 strain based inactivated H5N1 avian influenza vaccines against H5N8 virus isolated in wild birds

为评估当前应用的Re-8株种毒相关禽流感灭活疫苗对野鸟源H5N8流感病毒的免疫预防效果,本研究将重组禽流感病毒(AIV)H5亚型Re-8株灭活疫苗(H5N1亚型,Re-8株)和重组AIV(H5+H7)灭活疫苗(H5N1Re-8株+H7N9 H7 Re-1株)分别以0.3 m L/只的剂量接种3周龄SPF鸡,免疫3周时进行HI抗体检测和攻毒试验。结果显示,上述2种疫苗免疫的SPF鸡血清中针对H5亚型Re-8株抗原的HI抗体均在8 log2以上,以105EID50的剂量、鼻腔感染途径攻击野鸟源H5N8病毒BHG/QH/2/16和BHG/Tibet/3/16后,所有免疫组鸡在14 d观察期内均全部健活,不排毒,而对照组鸡在攻毒后4 d内全部发病、死亡、排毒。现地免疫重组AIV H5亚型三价灭活疫苗(Re-6株+Re-7株+Re-8株)的商品蛋鸡直接进行HI抗体检测和攻毒试验,结果显示,免疫蛋鸡血清中针对Re-8株抗原的HI抗体平均滴度为8.3 log2,以相同攻毒方式和剂量分别攻击2株H5N8病毒后,免疫鸡也获得完全免疫保护,不发病、不死亡、不排毒。本研究结果表明,含有重组AIV H5 Re-8株抗原的灭活疫苗可有效防控野鸟源H5N8流感病毒,为我国及其他国家H5N8亚型禽流感免疫防控提供了科学依据。

To evaluate the protection efficacy of the H5 avian influenza inactivated vaccines based on Re-8 strain currently used in China against H5N8 viruses isolated in wild birds, two groups of SPF chickens were vaccinated with l dose （0.3mL） of Re-8 inactivated vaccine and challenged intranasally with 105 EID50 of H5N8 viruses （BHG/QH/2/16 and BHG/Tibet/3/16）, respectively, at 3 weeks post immunization （wpi）. The Re-8＋H7-Re1 inactivated vaccine was evaluated in the same way with the same control groups. The results showed that the mean HI antibody titers to Re-8 antigen in the groups of immunized chickens were all above 8log2 at 3 wpi. All vaccinated chickens survived without virus shedding and clinical signs during the two weeks observation period post challenge, while all the chickens in the control groups died within 4 days post challenge. Furthermore, a total of 30 commercial layers immunized with the Re-6＋Re-7＋Re-8 trivalent inactivated vaccine were collected from the layer farm and randomly divided into two groups for challenge test against the same dose of BHG/QH/2/16 and BHG/Tibet/3/16, respectively. The results showed that the mean HI antibody titers to Re-8 strain were 8.3log2. After challenge with the H5N8 viruses, two groups of the commercial layers were completely protected without clinical signs and virus shedding during the two weeks observation period. Our data indicated that the H5N1 AIV inactivated vaccines containing Re-8 antigen were able to provide complete protection in chickens against the H5N8 virus circulating in wild birds. Our study provided important information for the control of H5N8 viruses in China and other countries.