Cross-Reactivity of Antipneumococcal Surface Protein C (PspC) Antibodies with Different Strains and Evaluation of Inhibition of Human Complement Factor H and Secretory IgA Binding via PspC
Cross-Reactivity of Antipneumococcal Surface Protein C (PspC) Antibodies with Different Strains and Evaluation of Inhibition of Human Complement Factor H and Secretory IgA Binding via PspC
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DOI：
10.1128/cvi.05706-11
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发表时间：
2012-04-01
影响因子：
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通讯作者：
Miyaji, Eliane N.
中科院分区：
文献类型：
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作者：
Moreno, Adriana T.;Oliveira, Maria Leonor S.;Miyaji, Eliane N.
肺炎球菌表面蛋白C(PSPC)是一种成本效益高、覆盖面广的肺炎球菌疫苗的重要候选疫苗。以往的研究表明，肺炎链球菌能够通过PSPC与补体替代途径的抑制因子H(FH)和人分泌型IgA(SIgA)结合。根据该基因的变异情况，将PSPC分为11类。在这项工作中，我们使用来自不同组的三个PSPC片段(PspC3、PspC5和PspC8)免疫小鼠以产生抗体。用PspC3免疫可识别大多数临床分离株的抗体，经全细胞印迹和完整细菌的流式细胞术分析，抗PspC5抗体与肺炎球菌表面蛋白A(PSPA)呈交叉反应，抗PspC8抗体仅与表达PspC8的菌株反应。大多数受试菌株与FH结合较强，与SIgA结合较弱。在Western blotting中，抗PspC3和抗PspC5抗体对FH的结合有一定的抑制作用，而抗PspC3抗体对SIgA结合有部分抑制作用。全菌流式细胞仪分析显示，D39株与抗PspC3抗体孵育后FH结合略有下降，1株临床分离株的SIgA结合被抗PspC3抗体抑制。我们的结论是，尽管抗PspC3抗体能够识别大多数受试菌株的PSPC变体，但只有有限数量的分离株能通过抗PspC3抗体在体外部分抑制FH和SIgA的结合。
Pneumococcal surface protein C (PspC) is an important candidate for a cost-effective vaccine with broad coverage against pneumococcal diseases. Previous studies have shown that Streptococcus pneumoniae is able to bind to both human factor H (FH), an inhibitor of complement alternative pathway, and human secretory IgA (sIgA) via PspC. PspC was classified into 11 groups based on variations of the gene. In this work, we used three PspC fragments from different groups (PspC3, PspC5, and PspC8) to immunize mice for the production of antibodies. Immunization with PspC3 induced antibodies that recognized the majority of the clinical isolates as analyzed by Western blotting of whole-cell extracts and flow cytometry of intact bacteria, while anti-PspC5 antibodies showed cross-reactivity with the paralogue pneumococcal surface protein A (PspA), and anti-PspC8 antibodies reacted only with the PspC8-expressing strain. Most of the isolates tested showed strong binding to FH and weaker interaction with sIgA. Preincubation with anti-PspC3 and anti-PspC5 IgG led to some inhibition of binding of FH, and preincubation with anti-PspC3 partially inhibited sIgA binding in Western blotting. The analysis of intact bacteria through flow cytometry showed only a small decrease in FH binding after incubation of strain D39 with anti-PspC3 IgG, and one clinical isolate showed inhibition of sIgA binding by anti-PspC3 IgG. We conclude that although anti-PspC3 antibodies were able to recognize PspC variants from the majority of the strains tested, partial inhibition of FH and sIgA binding through anti-PspC3 antibodies in vitro could be observed for only a restricted number of isolates.