The aim of this study was to identify virulence factors that have high immunogenicity. An in vivo-expressed Staphylococcus aureus antigen was identified by probing bacteriophage expression libraries of S. aureus with antibodies in bovine mastitis milk. Eighteen clones were isolated, and their proteins were identified as 5 characterised proteins (IsdA, Protein A, IsdB, autolysin, and imidazole glycerol phosphate dehydratase) and 13 hypothetical proteins. We focused on IsdA, IsdB, and IsdH as virulence factors that have a high immunogenicity and are capable of inducing a specific humoral immune response in S. aureus-infected quarters. The optical density (OD) values of IsdA and IsdB IgA and IgG antibodies in milk affected by naturally occurring mastitis caused by S. aureus increased significantly compared to those in healthy milk. In the experimental infection study, the OD values of IsdA- and B-specific IgA and IgG antibodies were significantly increased from 2 to 4 weeks after S. aureus infection compared to day 0 (P < 0.05). On the other hand, we demonstrated that milk from natural and experimental intramammary infections caused by S. aureus are associated with significantly higher IgA levels against IsdH (P < 0.05), but no significant change in IgG levels. Our findings facilitated our understanding of the pathogenicity of S. aureus in bovine mastitis, as well as the mechanisms by which specific humoral immune responses to S. aureus infection are induced. In addition, the results obtained could provide insight into how bovine mastitis can be controlled, for example, through vaccination.

本研究的目的是鉴定具有高免疫原性的毒力因子。的体内-expressed金黄色葡萄球菌抗原是由探测的噬菌体表达文库鉴定金黄色葡萄球菌与牛乳腺炎乳的抗体。分离出 18 个克隆，它们的蛋白质被鉴定为 5 个特征蛋白质（IsdA、Protein A、IsdB、自溶素和咪唑甘油磷酸脱水酶）和 13 个假设蛋白质。我们专注于 IsdA、IsdB 和 IsdH 作为具有高免疫原性并能够在金黄色葡萄球菌中诱导特异性体液免疫反应的毒力因子。感染的宿舍。与健康牛奶相比，受金黄色葡萄球菌引起的自然乳腺炎影响的牛奶中 IsdA 和 IsdB IgA 和 IgG 抗体的光密度 (OD) 值显着增加。在实验感染研究中，与第 0 天相比，金黄色葡萄球菌感染后 2 至 4 周，IsdA 和 B 特异性 IgA 和 IgG 抗体的 OD 值显着增加（P < 0.05）。另一方面，我们证明了由金黄色葡萄球菌引起的天然和实验性乳房内感染产生的牛奶与显着更高的 IgA 水平有关 IsdH（P < 0.05），但 IgG 水平没有显着变化。我们的发现促进了我们对金黄色葡萄球菌致病性的理解在牛乳腺炎中，以及诱导针对金黄色葡萄球菌感染的特异性体液免疫反应的机制。此外，获得的结果可以深入了解如何控制牛乳腺炎，例如，通过疫苗接种。