肺炎链球菌重组自溶酶(Re-LytA)滴鼻免疫小鼠的实验研究

摘要

Objective To evaluate the protective effectiveness of intranasal immunizations with recombinated-pneumococcal autolysin(Re-LytA), which protects mice against local and systemic Streptococ- cus pneumoniae(Sp) infection. Methods Testing group (group A): CpG as an adjuvant, the mice were intranasally immunized with purified Re-LytA, obtained by affinity chromatograph. The negative control group(group B) were intranasally immunized with sterile saline. And the positive control group (group C) were received 23-valent polysaccharide commercial vaccine through intramuscular injection. All the samples were collected 2 weeks post the last immunization. The levels of antibody was determined by ELISA. Then the mice were challenged intraperitoneally and intranasally with Sp, respectively. The infection and coloniza- tion was followed by monitoring colony-forming units of Sp in the blood, homogenized lung, and nasopharyn- geal lavage fluid 4 days post intranasal immunization. The mice were observed daily to note the livability of each group. Results The level of the LytA antibody (IgG, IgA, slgA) in group A were higher than that in group B and C (P < 0.05). Neither the LytA nor polysaccharide antibody could be detected in group B. Polysaccharide antibody could be detected in group C. After challenged intraperitoneally there was no signifi- cant difference in survival rates between group A and group C (P > 0.05), which was significant higher than that in group B (P <0.05). After challenged intranasally, compared with the group A, the geometric mean colony-forming units washed from the nasopharyngeal lavage fluid of the group B and group C were signifi- cantly higher (P <0.05). Conclusion lntranasal immunizations with Re-LytA can protect mice against lo- cal and systemic pneumococcal infection, and the protective immunity may be related to sIgA.%目的 评价重组肺炎链球菌(Streptococcus pneumoniae,Sp)自溶酶(autolysin,LytA)滴鼻免疫诱导小鼠抗Sp感染的保护性效果.方法 用亲和层析的方法纯化出重组Sp LytA蛋白,以CpG作佐剂,对小鼠进行滴鼻免疫(A组).对照组(B组)用无菌盐水滴鼻;多糖疫苗组(C组)用23价多糖疫苗肌肉注射.于末次免疫后2周,用Sp分别以滴鼻和腹腔注射两种方式进行攻击感染.攻击之前采集血清和鼻咽灌洗液等样品,采用ELISA测试其抗体水平.滴鼻攻击后4 d,采集小鼠鼻咽灌洗液和肺灌洗液,进行Sp细菌计数;腹腔注射攻击后7 d内观察各组小鼠死亡情况.结果 B组未检测到LytA抗体和多糖抗体,C组多糖抗体阳性;A组LytA抗体(包括tgG、IgA、sIgA)均明显高于对照组,差异具有统计学意义(P<0.05).腹腔注射攻击后,A、C组小鼠的存活率明显高于B组(P<0.05),A组和C组之间没有明显区别(P>0.05).滴鼻攻击后,A组鼻咽部灌洗液Sp细菌计数明显低于B组和C组(P<0.05).结论 Re-LytA滴鼻免疫可诱导实验小鼠产生一定的抵抗Sp感染的保护性免疫力,这种保护性的免疫力可能与sIgA相关.