鱼用嗜水气单胞菌口服疫苗的免疫保护效应

IMMUNOGENECITY AND PROTECTIVE EFFECTS OF AN ORAL VACCINE MICROPARTICLE AGAINST AEROMONAS HYDROPHILA IN GRASS CARP (CTENOPHARYNGODON IDELLA)

目的:制备含嗜水气单胞菌被膜或全菌的PLG疫苗微粒,以草鱼为实验动物,研究疫苗微粒的免疫保护效应。方法:采用复乳挥发法制备PLG疫苗微粒,草鱼口服免疫在4周内进行3次(每次10 mg微粒),用ELISA法测定血清和肠粘液的抗体变化,保护效应用细菌攻击实验检测。结果:获得被膜和全菌的PLG疫苗微粒,蛋白含量分别为2.31%,6.12%,2种疫苗微粒均可诱导血清及肠粘液抗体应答。腹腔接种20 LD50嗜水气单胞菌后,被膜、全菌疫苗微粒组的存活率分别为46.7%和36.7%,相对存活率分别为42.9%和32.1%,接受空微粒的草鱼仅有6.7%的存活率。结论:被膜、全菌疫苗微粒对草鱼均有显著免疫保护效应,可作为预防嗜水气单胞菌感染的疫苗。

Vaccine microparticles were prepared using the solvent evaporation method. Their effects were investigated in grass carp （Ctenopharyngodon idella） by oral administration of three doses of 10 mg CE （cell envelops ） -entrapped microparticles （containing 231 μg protein） or 10 mg WC （ whole cell）-entrapped microparticles （ containing 612 μg protein） in 4 weeks. Antibodies in the serum and the intestinal mucus were detected by ELISA. The protective effects of the vaccine microparticles were examined by bacterial challenge. The PLG [ poly（ lactide-co-glycolide） ] microparticles entrapping the cell envelopes or the killed whole cells were obtained, both of which elicited higher serum antibody responses and lower intestinal mucus antibody level. After challenge with 20 LD50 of Aeromonas hydrophila, the survival rate of the fish receiving cell envelopes or whole-cell vaccine was 46.7% or 36.7%, and their relative survival rate was 42.9% or 32.1%, respectively. In contrast, the survival rate of the control grass carp, which had received free microparticles, was a mere 6.7%. it is thus concluded that both vaccine microparticles in this study had a significant protective effect on grass carp and might be used as effective fish vaccines against Aeromona. hydrophila infection.