Galán J E, Timoney J F
Department of Veterinary Microbiology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853.
J Clin Microbiol. 1988 Jun;26(6):1142-6. doi: 10.1128/jcm.26.6.1142-1146.1988.
A series of isolates of Streptococcus equi from the United States and Europe were compared by the bactericidal test, immunoblotting, DNA restrictions, and Southern hybridization analysis. All isolates tested were sensitive to the same bactericidal serum. In addition, immunoblotting revealed no differences in M proteins prepared by acid or mutanolysin extraction. Immunoblotting of acid extracts of the isolates with mucosal nasopharyngeal mucus from a convalescent horse revealed the presence of the 41,000- and 46,000-Mr polypeptide fragments of the M protein of S. equi known to be important in stimulating mucosal nasopharyngeal immune responses. DNA restriction analysis of total cell DNA digests, as well as Southern hybridizations using an S. equi M protein gene probe, did not detect any differences among these isolates. Our results, therefore, confirm the antigenic homogeneity of the M proteins of S. equi isolates and suggest that variation in this antigen is not a reason for the failure of commercial vaccines in the field. Interestingly, the protoplast M proteins of all isolates showed remarkable size homogeneity, in contrast to the size variation reported in M proteins of group A streptococci.
通过杀菌试验、免疫印迹、DNA限制酶切和Southern杂交分析，对来自美国和欧洲的一系列马链球菌分离株进行了比较。所有测试的分离株对同一种杀菌血清敏感。此外，免疫印迹显示，通过酸提取或变溶菌素提取制备的M蛋白没有差异。用康复马的鼻咽粘膜粘液对分离株的酸提取物进行免疫印迹，结果显示存在马链球菌M蛋白的41,000和46,000道尔顿的多肽片段，已知这些片段在刺激鼻咽粘膜免疫反应中很重要。对总细胞DNA消化物进行的DNA限制酶切分析，以及使用马链球菌M蛋白基因探针进行的Southern杂交，均未检测到这些分离株之间存在任何差异。因此，我们的结果证实了马链球菌分离株M蛋白的抗原同质性，并表明该抗原的变异不是商业疫苗在实际应用中失败的原因。有趣的是，所有分离株的原生质体M蛋白在大小上显示出显著的同质性，这与A组链球菌M蛋白中报道的大小变异形成对比。
