罗非鱼无乳链球菌SIP微胶囊口服疫苗免疫效果研究

摘要

为研究无乳链球菌Streptococcus agalactiae表面免疫蛋白(surface immunogenic protein,SIP)微胶囊口服疫苗对罗非鱼Oreochromis niloticus的免疫效果,将制备的无乳链球菌SIP微胶囊疫苗口服免疫健康的罗非鱼,以注射免疫无乳链球菌灭活疫苗为阳性对照,口服包埋PBS的微胶囊颗粒为阴性对照,分别于免疫后0、7、14、28 d取脾脏组织,通过实时荧光定量PCR方法检测脾脏组织中的白细胞分化抗原CD4、白介素IL-8、IL-10、肿瘤坏死因子TNF-α、核转录因子NF-κB等5种免疫相关基因表达的变化,并于第5周进行人工感染攻毒试验,计算无乳链球菌SIP微胶囊口服疫苗对罗非鱼的相对免疫保护率.结果显示,免疫接种之后,SIP微胶囊疫苗口服免疫组(SIP疫苗组)和全菌灭活疫苗注射免疫组(灭活疫苗组)罗非鱼脾脏中的5种免疫相关基因表达均不同程度上调,且相对表达量显著高于阴性对照免疫组(阴性对照组)(P<0.05).在人工感染攻毒试验中,SIP疫苗组和灭活疫苗组的死亡率均显著低于阴性对照组(P<0.05),灭活疫苗组比SIP疫苗组得到了更高的免疫保护率,但两组的死亡率差异不显著(P>0.05).说明罗非鱼无乳链球菌SIP微胶囊口服疫苗免疫效果好,在罗非鱼无乳链球菌病的免疫防治中有良好的应用前景.%The immunological efficacy of Streptococcus agalactiae surface immunogenic protein (SIP) oral vaccine on tilapia (Oreochromis niloticus) was studied .Randomly grouped fish were injected with the inactivated vaccine as the positive control (Group Inactivated Vaccine) ,or orally administered with SIP vaccine (Group SIP Vaccine) for treatment or PBS as the negative control (Group Negative Control) .Spleen samples from the tilapias were collected at 0 ,7 ,14 and 28 d after the immunization .The gene expressions of the cluster determinant 4 (CD4) ,interleukin-8 (IL-8) ,interleukin-10 (IL-10) ,tumor necrosis factor α(TNF-α) and nuclear transcription factors κB (NF-κB) were determined by the quantitative reverse transcription-polymerase chain reaction (qRT-PCR) .Four weeks after the treatments ,the groups were challenged by the artificial infection of S .agalactiae to observe the relative percent survivals(RPS)onthefish.TheresultsshowthattheexpressionsonCD4,IL-8,IL-10,TNF-αandNF-κBgenes of Group SIP Vaccine and Group Inactivated Vaccine increased in varying degrees ,and were significantly higher (P<0.05) than those of Group Negative Control .The death rates of fish in Group SIP Vaccine and Group Inactivated Vaccine were significantly lower (P<0.05) than that of Group Negative Control .The RPS of Group Inactivated Vaccine was higher than that of Group SIP Vaccine ,but not significantly different (P>0.05) .It appeared that the SIP oral vaccine could be used with satisfaction in protecting tilapias from S .agalactiae infection .