Rainard P, Lautrou Y, Sarradin P, Poutrel B
Laboratoire de Pathologie Infectieuse et d'Immunologie, Institut National de la Recherche Agronomique, Nouzilly, France.
J Clin Microbiol. 1991 Sep;29(9):1842-6. doi: 10.1128/jcm.29.9.1842-1846.1991.
Protein X of Streptococcus agalactiae is a surface protein frequently associated with strains isolated from cases of mastitis of dairy cows. By immunizing cows with purified protein X, we obtained an antibody response which was restricted to X-bearing strains of S. agalactiae in a whole-cell enzyme-linked immunosorbent assay. This response resulted in an increase in the opsonic activity of serum for strains bearing protein X, as assessed through the augmentation of the chemiluminescence response of phagocytosing polymorphonuclear cells and through an increased ingestion of bacteria, although the proportion of ingested bacteria which were killed (about 60%) remained unchanged. Protein X behaved as a target of opsonins and, as such, could be a protective antigen worth incorporating in a vaccine against S. agalactiae mastitis.
无乳链球菌的X蛋白是一种表面蛋白，常与从奶牛乳腺炎病例中分离出的菌株相关。通过用纯化的X蛋白免疫奶牛，我们获得了一种抗体反应，在全细胞酶联免疫吸附试验中，该反应仅限于携带X蛋白的无乳链球菌菌株。通过吞噬多形核细胞化学发光反应的增强以及细菌摄取量的增加评估，这种反应导致血清对携带X蛋白菌株的调理活性增加，尽管被杀死的摄取细菌比例（约60%）保持不变。X蛋白表现为调理素的靶标，因此可能是一种值得纳入抗无乳链球菌乳腺炎疫苗的保护性抗原。
