重组质粒pcDNA3-dnaJ/蛋白DnaJ异源免疫诱导Th1和Th17细胞免疫应答抵抗肺炎链球菌感染 *

目的 探索更有效的肺炎链球菌DNA疫苗和疫苗免疫策略,并探究其中的保护机制。方法 构建重组质粒pcDNA3-dnaJ并表达DnaJ蛋白,实验分别设置重组质粒pcDNA3-dnaJ/蛋白DnaJ免疫小鼠组及单独质粒pcDNA3-dnaJ免疫小鼠组,分别比较肺炎链球菌菌株攻毒后小鼠鼻腔灌洗液细菌载量及生存率,采用ELISA检测免疫小鼠血清抗体效价及炎症因子,流式细胞术分析体外BMDCs激活情况及Th1和Th17细胞免疫应答。结果 质粒pcDNA3-dnaJ免疫3次可诱导血清中抗原特异性抗体的产生,并减少肺炎链球菌攻毒后鼻咽部的细菌载量,但在防止致死性感染方面效果较差。然而,与重复质粒DNA接种三次相比,pcDNA3-dnaJ 1次/ DnaJ蛋白加强1次的免疫策略可以显著减少鼻咽中的肺炎链球菌定植,并能够更好的预防致死性感染。此外,与DNA质粒加强免疫相比,DnaJ蛋白加强免疫后可产生更高水平的IFN-γ和IL-17A。结论 重组质粒pcDNA3-dnaJ/蛋白DnaJ异源免疫可能通过活化树突状细胞,进而诱导Th1和Th17细胞免疫应答,抵抗肺炎链球菌感染。

Recombinant Plasmid pcDNA3-dnaJ Prime/DnaJ Protein Boost Immunization Induce Th1/Th17 Immune Responses and Protect Mice Against Pneumococcal Infection

Objective: To explore more effective S. pneumoniae DNA vaccines and vaccine immunization strategies and explore their protective mechanisms.Methods: The recombinant plasmid pcDNA3-dnaJ was constructed and DnaJ protein was expressed. The recombinant plasmid pcDNA3-dnaJ/protein DnaJ immunized group and the plasmid pcDNA3-dnaJ immunized group were separately set to compare the nasal lavage of mice treated with S. pneumoniae strain. The bacterial load and survival rate of the liquid, serum antibody titer and inflammatory factors after challenged were measured by ELISA. The activation of BMDCs and the immune responses of Th1 and Th17 cells were analyzed by flow cytometry.Methods: The plasmid pcDNA3-dnaJ immunization three times induced antigen-specific antibody in serum and reduced the bacterial loads in the nasopharynx after challenge with live S. pneumoniae, but it was less effective in protecting against a lethal infection. However, compared with repeating the plasmid DNA innoculation three times, the strategy of pcDNA3-dnaJ prime one time/DnaJ protein boost one time could significantly reduce the pneumococcal colonization in the nasopharynx and provid better protection against lethal infection. Furthermore, DnaJ protein boosting generated higher levels of IFN-γ and IL-17A than the DNA boosting.Conclusion: Compared with DNA plasmid booster, immunization using DNA prime/protein boost of pneumococcus protein may be a new strategy to develop vaccines against pneumococcal infection.