Gluck Equine Research Center, University of Kentucky, Lexington, KY, 40546, USA.
Gluck Equine Research Center, University of Kentucky, Lexington, KY, 40546, USA.
Vet Microbiol. 2018 Jun;219:113-116. doi: 10.1016/j.vetmic.2018.04.015. Epub 2018 Apr 14.
The constitutively expressed hyaluronic acid capsule is an important virulence factor of Streptococcus equi, the cause of equine strangles. Study of the genomic sequence of CF22caps-, a non-encapsulated mutant of S. equi CF22 generated by gamma (Co) irradiation revealed a non-sense mutation in fasC (SEQ_0302), a sensor kinase gene in FasBCAX an operon with an important regulatory role in expression of streptococcal secreted virulence and matrix binding proteins. The mutation was associated with a significant (p < .05) decrease in transcription of hasA, the synthase gene essential for hyaluronic acid synthesis and, conversely, with small increases in transcription of skc, covR and seM. The early growth phase of CF22caps- was also delayed compared to the CF22caps parent. In contrast to the human pathogen, S. pyogenes, capsule synthesis in S. equi therefore appears to be controlled by FasBCAX and not by CovRS.
固有表达的透明质酸荚膜是马链球菌兽疫亚种（引起马腺疫的病原体）的一个重要毒力因子。对马链球菌 CF22 的非荚膜突变株 CF22caps-的基因组序列进行研究，该突变株是通过γ（Co）辐照产生的，结果发现 FasBCAX 操纵子中的一个传感器激酶基因 fasC（SEQ_0302）发生了无义突变，该操纵子在调节链球菌分泌的毒力因子和基质结合蛋白的表达方面具有重要作用。该突变与透明质酸合成所必需的合成酶基因 hasA 的转录显著降低（p < .05）有关，而与 skc、covR 和 seM 的转录小幅度增加有关。与 CF22caps-亲本相比，CF22caps-的早期生长阶段也被延迟。与人类病原体化脓链球菌不同，马链球菌的荚膜合成似乎是由 FasBCAX 而不是 CovRS 控制的。
