Su Yufeng, Li Dagen, Xing Yan, Wang Hong, Wang Jian, Yuan Jun, Wang Xiaofang, Cui Fang, Yin Yibing, Zhang Xuemei
Department of Laboratory Medicine, Key Laboratory of Diagnostic Medicine (Ministry of Education), Chongqing Medical University, Chongqing, China.
Department of Laboratory Medicine, People's Hospital of Changshou, Chongqing, China.
Front Immunol. 2017 Jun 12;8:686. doi: 10.3389/fimmu.2017.00686. eCollection 2017.
Subunit vaccines that are poorly immunogenic are often combined with adjuvants for immunization. Our previous research identified a pneumolysin variant (ΔA146Ply), a Toll-like receptor 4 agonist, that was an effective adjuvant in the protection of fusion protein DnaJ-ΔA146Ply against mucosal infections. For pneumococcal vaccines, World Health Organization recommend injection as a regular vaccination approach. Subcutaneous immunization is a common and effective method of injection, so we explored the immunity mechanism of subcutaneous immunization with DnaJ-ΔA146Ply. We found that mice immunized subcutaneously with fusion proteins ΔA146Ply-DnaJ and DnaJ-ΔA146Ply produced a higher anti-DnaJ IgG titer than when DnaJ alone was administered. DnaJ-ΔA146Ply induced both B-cell and T-cell-dependent protection against both colonization and lethal pneumococcal infections. Levels of IFN-γ, IL-4, and IL-17A were also elevated in DnaJ-ΔA146Ply immunized mice. However, all these effects were negated in TLR4 mice compared to WT mice immunized with DnaJ-ΔA146Ply. B-cell-deficient μMT mice, nude mice, IFN-γ, and IL-4 mice immunized with DnaJ-ΔA146Ply could not resist infection with pneumococci. IL-17A and TLR4 mice did not benefit from DnaJ-ΔPly immunization in colonization experiments although their survival was not impaired compared with WT mice. Collectively, our data indicated that ΔA146Ply can be a potential subcutaneous adjuvant, and the DnaJ-ΔA146Ply fusion protein induces both humoral and cellular immune response to resist infection. The protective effect of colonization also depends on TLR4.
免疫原性较差的亚单位疫苗通常与佐剂联合用于免疫接种。我们之前的研究鉴定出一种肺炎溶血素变体（ΔA146Ply），它是一种Toll样受体4激动剂，在保护融合蛋白DnaJ-ΔA146Ply抵抗黏膜感染方面是一种有效的佐剂。对于肺炎球菌疫苗，世界卫生组织推荐注射作为常规接种方法。皮下免疫是一种常见且有效的注射方法，因此我们探索了用DnaJ-ΔA146Ply进行皮下免疫的免疫机制。我们发现，用融合蛋白ΔA146Ply-DnaJ和DnaJ-ΔA146Ply皮下免疫的小鼠产生的抗DnaJ IgG滴度高于单独给予DnaJ时。DnaJ-ΔA146Ply诱导了针对定植和致死性肺炎球菌感染的B细胞和T细胞依赖性保护。在用DnaJ-ΔA146Ply免疫的小鼠中，IFN-γ、IL-4和IL-17A的水平也有所升高。然而，与用DnaJ-ΔA146Ply免疫的野生型小鼠相比，在TLR4基因敲除小鼠中所有这些效应均消失。用DnaJ-ΔA146Ply免疫的B细胞缺陷型μMT小鼠、裸鼠、IFN-γ和IL-4基因敲除小鼠无法抵抗肺炎球菌感染。在定植实验中，IL-17A和TLR4基因敲除小鼠虽然与野生型小鼠相比其生存未受损害，但并未从DnaJ-ΔPly免疫中获益。总体而言，我们的数据表明ΔA146Ply可能是一种潜在的皮下佐剂，并且DnaJ-ΔA146Ply融合蛋白诱导体液免疫和细胞免疫反应以抵抗感染。定植的保护作用也依赖于TLR4。
