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目的探讨肺炎链球菌减毒活菌疫苗候选菌株R6的安全性及保护效果。方法将不同剂量的R6和强毒力菌株D39分别经鼻腔感染BALB/c小鼠,通过小鼠毒力试验、定植试验和肺部组织形态观察,评价R6的安全性。将1.0×108cfu的R6菌株与CT佐剂混合后,经黏膜免疫BALB/c小鼠,采用ELISA法检测小鼠血清中IgG亚型及细胞因子,通过主动、被动保护试验及免疫小鼠体内定植试验,观察R6对免疫小鼠的保护效果。结果不同剂量的R6鼻腔攻毒后,小鼠存活率为100%,显著高于D39阳性对照组(P<0.001),心脏血和脑匀浆标本未见细菌生长,鼻腔灌洗液和肺匀浆中的菌量均显著低于D39阳性对照组(P<0.01),肺部炎症反应较轻,且较快恢复正常。R6菌株与CT佐剂混合后经黏膜免疫的小鼠可产生以IgG1和IgG2b亚型为主的高效价血清IgG,且特异性的细胞因子IL-4、IL-10和IL-17A水平明显升高;可主动保护60%的小鼠抵抗D39的感染,明显高于市售23价肺炎链球菌疫苗(44%),但免疫血清不具有被动保护作用;免疫R6的小鼠可明显减少19F菌株在其呼吸系统的定植。结论肺炎链球菌减毒活疫苗候选菌株R6具有良好的安全性和保护效果,为该疫苗的研发提供了实验依据。
Objective To investigate the safety and protective effect of Streptococcus pneumoniae attenuated viable vaccine candidate strain R6. Methods Different doses of R6 and virulent strain D39 were respectively infected into BALB / c mice through nasal cavity. The safety of R6 was evaluated by virulence test, colonization test and lung morphology in mice. BALB / c mice were immunized with 1.0 × 108cfu of R6 strain and CT adjuvant, and the IgG subtypes and cytokines in serum were detected by ELISA. The mice were immunized by active and passive protection and colonized in vivo Test to observe the protective effect of R6 on the immunized mice. Results After different dosages of rh-nasal challenge, the survival rate of mice was 100%, which was significantly higher than that of D39 positive control group (P <0.001). No bacterial growth was found in cardiac blood and brain homogenate samples. Nasal lavage fluid and lung homogenate The amount of bacteria in the pulp was significantly lower than that in the D39 positive control group (P <0.01). The lung inflammation was lighter and returned to normal quickly. Mice immunized with R6 strain and CT adjuvant were immunized with mucosa to produce high titer IgG with IgG1 and IgG2b isoforms, and the levels of specific cytokines IL-4, IL-10 and IL-17A were significantly increased 60% of the mice could actively protect against D39 infection, which was significantly higher than that of the commercially available 23-valent pneumococcal vaccine (44%), but the immune serum did not have passive protection; mice immunized with R6 significantly reduced 19F strain Colonization in their respiratory system. Conclusion Streptococcus pneumoniae attenuated live vaccine candidate strain R6 has good safety and protective effect, providing an experimental basis for the development of the vaccine.