College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
College of Animal Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
Microb Pathog. 2018 May;118:39-47. doi: 10.1016/j.micpath.2018.03.007. Epub 2018 Mar 6.
The GapC protein of Staphylococcus aureus (S. aureus) is a surface protein that is highly conserved among Staphylococcus strains, and it can induce protective humoral immune responses. However, B-cell epitopes in S. aureus GapC have not been reported. In this study, we generated a monoclonal antibody (mAb2A9) targeting S. aureus GapC. Through a passive immunity test, mAb2A9 was shown to partially protect mice against S. aureus infection. We screened the motif PVATGSLTE that is recognized by mAb2A9 using a phage-display system. The motif sequence exactly matched amino acids 236-243 of the S. aureus GapC protein. Then, we identified the key amino acids in the motif using site-directed mutagenesis. Site-directed mutagenesis revealed that residues P236, G240, L242, and T243 formed the core of the PVATGSLT motif. In addition, this epitope was proven to be located on the surface of S. aureus, and it induced a protective humoral immune response against S. aureus infection in immunized mice. Overall, our results characterized a conserved B-cell epitope, which will be an attractive target for designing effective epitope-based vaccines against S. aureus infection.
金黄色葡萄球菌（S. aureus）GapC 蛋白是一种高度保守的表面蛋白，存在于多种金黄色葡萄球菌菌株中，能够诱导保护性体液免疫应答。然而，金黄色葡萄球菌 GapC 的 B 细胞表位尚未被报道。在本研究中，我们制备了靶向金黄色葡萄球菌 GapC 的单克隆抗体（mAb2A9）。通过被动免疫实验，mAb2A9 部分保护了小鼠免受金黄色葡萄球菌感染。我们使用噬菌体展示系统筛选出被 mAb2A9 识别的肽段 PVATGSLTE。该肽段序列与金黄色葡萄球菌 GapC 蛋白的 236-243 位氨基酸完全匹配。然后，我们通过定点突变鉴定出该肽段中的关键氨基酸。定点突变显示，残基 P236、G240、L242 和 T243 构成了 PVATGSLT 基序的核心。此外，该表位被证明位于金黄色葡萄球菌表面，在免疫小鼠中能够诱导针对金黄色葡萄球菌感染的保护性体液免疫应答。总之，我们的研究结果鉴定了一个保守的 B 细胞表位，这将是设计针对金黄色葡萄球菌感染的有效表位疫苗的有吸引力的靶标。
