To study the immunogenicity of EsxA protein of Staphylococcus aureus, the EsxA-pET-28a recombinant plasmid was constructed and the expression product was analyzed by SDS-PAGE and Western blotting after the positive recombinant plasmid was induced by IPTG. Mice were immunized with purified EsxA protein and then the IgG, IgG1 and IgG2a antibody were detected with indirect ELISA. Then the histopathological examination, bacteria loading and immune protection of immunized mice were studied after challenge with S. aureus. The recombinant protein EsxA was successfully induced and expressed. After immunization the EsxA specific antibody titer could reach 1:900. Bacteria loading and pathological damage of liver, spleen and kidney were reduced after immunization with EsxA in the immunized mice. The protection rate of immunized mice was 75%. In conclusion, EsxA protein has good immunogenicity.
为分析牛乳源金黄色葡萄球菌 (Staphylococcus aureus) EsxA 蛋白的免疫原性，构建EsxA-pET-28a 重组表达质粒，重组质粒经诱导表达后进行SDS-PAGE 和Western blotting 鉴定。用纯化后重组EsxA 蛋白免疫小鼠，用间接ELISA 检测免疫小鼠血清中的IgG、IgG1 和IgG2a 水平；免疫小鼠经S. aureus 菌株攻击后，检测小鼠肝、脾、肾组织荷菌数和免疫保护率，观察S. aureus 菌株攻击后小鼠肝、脾、肾病理组织学变化。结果表明，成功诱导表达了EsxA 重组蛋白，该重组蛋白免疫小鼠后血清抗体效价可达1∶900，与对照相比，重组蛋白免疫后可减少小鼠肝、脾、肾组织的荷菌数，减轻这些脏器的病理损伤，对免疫小鼠保护率达75%。上述结果表明，该重组EsxA 蛋白具有良好的免疫原性。.
Keywords: EsxA protein; Staphylococcus aureus; immunogenicity; prokaryotic expression.