肺炎链球菌胆碱结合蛋白A在社区获得性肺炎诊断中的应用

Application of pneumococcal choline binding protein A in the diagnosis of community-acquired pneumonia

摘要:

目的： 探索以肺炎链球菌胆碱结合蛋白A（pneumococcal choline binding protein A，rCbpA）为抗原的酶联免疫吸附试验（enzyme-linked immunosorbent assay，ELISA）反应模型在肺炎球菌性社区获得性肺炎患者（community acquired pneumonia，CAP）检测中的应用价值。方法： 设计合成cbpA基因序列引物，通过PCR扩增，构建克隆质粒PGM-T/cbpA和表达质粒。经异丙基硫代半乳糖苷（isopropyl phosphorothioate，IPTG）诱导表达重组蛋白rCbpA；构建ELISA反应模型（rCbpA作为抗原），检测健康组及肺炎球菌性CAP患者组血清中相应的IgM和IgG抗体。并与痰培养、血培养结果相比较。运用卡方检验分析结果差异。结果： 成功获得肺炎链球菌重组蛋白rCbpA，建立rCbpA-ELISA模型。以rCbpA-IgM模式检测肺炎球菌性CAP患者组的敏感性为22.5%，与血培养及痰培养法检测的敏感性无统计学差异（χ²=3.529，P=0.060；χ²=0.075，P=0.785）；但其特异性为100%，明显高于痰培养（χ²=12.754，P=0.000）。rCbpA-IgG模式检测肺炎球菌性CAP患者组的敏感性为50%，与血培养、痰培养检测的敏感性差异具有统计学意义（χ²=17.635，P=0.000；χ²=7.912，P=0.005）。结论： 血清重组蛋白rCbpA对IgM类抗体有高特异性、对IgG类抗体有高敏感性，且该检测方法快，判定结果更准确客观，可以有效提高肺炎球菌感染性肺炎的诊断价值。

Abstract:

Objective: To investigate the applicative value of enzyme-linked immunosorbent assay (ELISA) reaction model which took pneumococcal choline binding protein A (rCbpA) as antigen in detecting patients with community acquired pneumonia (CAP). Methods: The specific primers of cbpA gene sequence were designed and synthetized, and proliferated according to PCR, finally, the cloning plasmids PGM-T/cbpA and expressing plasmids were constructed. Recombinant rCbpA was expressed after the inducing of isopropyl phosphorothioate (IPTG); ELISA model (rCbpA as antigen) was constructed and was used to detect IgM and IgG in the control group and CPA group. And results were compared with sputum culture and blood culture and were analyzed by Chi-square text. Results: The recombinant protein CbpA was obtained and rCbpA-ELISA was established. The sensitivity detected by the rCbpA-IgM in pneumococcal CAP patients was 22.5%, which had no statistically significant difference by blood and sputum culture method (χ²=3.529, P=0.060; χ²=0.075, P=0.785). But its specificity was 100%, which was significantly higher than that by sputum culture (χ²=12.754, P=0.000). The sensitivity detected by rCbpA-IgG mode to detect pneumococcal CAP patients was 50%, which was statistically different from the sensitivity by blood culture and sputum culture (χ²=17.635, P=0.000; χ²=7.912, P=0.005). Conclusion: The serum recombinant protein rCbpA has high specificity to IgM and high sensitivity to IgG. Moreover, advantages including fast detection and objective judgment result, can improve the diagnostic value of pneumococcal infections.