猪链球菌2型缺失菌株ΔNisKR免疫保护力的研究

Streptococcus suis (S. suis) is an important zoonotic pathogen causing severe systemic infection in humans, especially serotype 2, causes significant economic losses to the swine industry and threats to human health worldwide. In order to more effectively controlling the occurrence and spread of S. suis 2 disease, development of the a live attenuated candidate vaccine is an effective way. In this study, ΔNisKR derived from SC19 is studied as a live attenuated vaccine, which provided significantly greater protective efficacy against challenge with a lethal dose of S. suis 2 in a mouse model compared with the blank or negative control groups. The results revealed that the ΔNisKR mutant elicited a strong humoral antibody response; both IgG1 and IgG2 subclasses were induced. Moreover, the antisera against the mutant were bactericidal in a whole blood assay and provided 50% protective efficacy against S. suis 2 infection in a passive immunization experiment. In addition, a significant proliferative T-cell immune response was noted in a lymphocyte proliferation assay. Performing numerous immunological assays for determination of immunogenicities, we demonstrated that the mutant immunization, which provided significant protective immunity, would offer insight into the underlying immune mechanisms of a bacterial live attenuated vaccine and provide a novel strategy against S. suis 2 infection.