口服甲型副伤寒沙门菌致病岛2缺失株对小鼠的免疫保护效力评估

The immunoprotective efficacy of a Salmonella Paratyphi A pathogenicity island 2 mutant through oral inoculation in mice

目的评估甲型副伤寒沙门菌致病岛2缺失株(SPA017ΔSPI2)对小鼠的免疫保护效力,研制有效的甲型副伤寒沙门菌减毒口服疫苗。方法以1×10~8菌落形成单位(CFU)的SPA017ΔSPI2对6周龄的雌性Balb/c小鼠进行口服免疫,7 d后以相同剂量进行二次免疫,测定小鼠体质量变化、SPA017ΔSPI2体内定植水平、血清抗体水平和脾脏淋巴细胞增殖水平,并对SPA017ΔSPI2亲本株SPA017攻毒后的保护效力进行评价。结果 SPA017ΔSPI2免疫后不影响小鼠的生长性能,该缺失株在小鼠体内具有一定的定植能力,且SPA017ΔSPI2能够诱导小鼠产生显著的体液免疫应答和细胞免疫应答反应,攻毒后免疫组小鼠的发病率和死亡率均显著低于对照组。结论甲型副伤寒沙门菌致病岛2缺失株经口服免疫后可对小鼠提供良好的免疫保护,可以作为甲型副伤寒理想的疫苗候选株。

To evaluate the immunoprotective efficacy of a Salmonella Paratyphi A pathogenicity island 2 mutant(SPA017ΔSPI2) and develop an effective attenuated oral vaccine, six-week-old female Balb/c mice were orally immunized with 1 × 10~8 CFU SPA017ΔSPI2 each mouse, and then secondary immunization was preformed with the same dose 7 days later. Data showed there was no differences in body weight or clinical symptoms between the mice of control group and the immunized mice;SPA017ΔSPI2 bacteria could colonize and persistent a short period of time in the liver and spleen of mice;specific humoral and cellular immune responses were also significantly induced in immunized mice. SPA017ΔSPI2 immunization in mice offered efficient protection against Salmonella Paratyphi A strain SPA017 at 14 days post-immunization(dpi) based on mortality and clinical symptoms. Overall, these results demonstrate that SPA017ΔSPI2 can provide efficient protection against Salmonella Paratyphi A infection and may be regard as a live attenuated oral vaccine candidate.