SIP亚单位疫苗对无乳链球菌诱导小鼠乳腺炎的保护力评价

摘要

无乳链球菌是导致奶牛乳腺炎的重要病原菌，本研究评价了SIP（surfaceimmunogenicprotein）亚单位疫苗对小鼠无乳链球菌乳腺炎的免疫保护效果。制备无乳链球菌SIP亚单位疫苗和灭活疫苗，对小鼠进行免疫，并设PBS阴性对照。免疫前后采血测定IgG及IgG亚类的抗体滴度。免疫小鼠分娩后第4天，进行无乳链球菌乳腺攻毒试验。24h后扑杀攻毒鼠，进行乳腺内CFU的测定，制作并观察乳腺组织病理切片。结果显示，SIP亚单位疫苗免疫组IgG及IgG亚类抗体滴度显著高于灭活疫苗组（P〈O．01）。免疫哺乳小鼠乳腺攻毒后，SIP亚单位疫苗免疫组小鼠乳腺CFU显著低于灭活疫苗组及对照组（P〈O．001）o乳腺病理切片显示SIP亚单位疫苗组乳腺组织结构较对照组完整，且中性粒细胞浸润程度最小。本研究表明，无乳链球菌SIP亚单位疫苗有望作为奶牛无乳链球菌乳腺炎的候选亚单位疫苗。%Streptococcus agalactiae （S. agalactiae） is a major cause of bovine mastitis. In the present study we assessed the efficacy of the surface immunogenic protein （SIP） as a mastitis vaccine in a mouse model. Three groups of mice were immunized with either SIP, inactivated S. agalactiae, or PBS as a control. IgG, IgG subtype and the capability of adhesion were evaluated. IgG and IgG subtype titers of mice in the SIP vaccine group were significantly higher than those in the killed vaccine group （P 〈0.01）. Immunized lactating mice were challenged with S. agalactiae via the intramammary route. Significantly fewer bacteria were recovered from mice in the SIP group than from those in the killed vaccine group （P 〈0.001）. Histopathology indicated that the mammary structure showed greater integrity and a milder inflammatory response in the SIP group as compared with both the inactivated vaccine and PBS control groups. These results suggested that the SIP protein may be an attractive target for a vaccine against S. agalactiae -induced mastitis.