马源马链球菌兽疫亚种新疆株的分离鉴定及遗传特性分析

Isolation,Identification and Genetic Characterization Analysis of Streptococcus equi subsp. zooepidemicus from Horse in Xinjiang

为了解马源马链球菌兽疫亚种(S.zooepidemicus)新疆分离株马链球菌兽疫亚种类M蛋白(SzM)基因的分子进化与变异情况,为该菌引起的感染性疾病的防控提供依据,本试验对新疆地区某马场采集的病马淋巴结样品进行病原菌的分离培养和生化鉴定,并对分离菌株进行药物敏感性试验。根据已发表的马源SzM基因序列设计引物,对其SzM基因进行PCR扩增及序列测定。将获得的SzM序列与GenBank中不同动物源马链球菌兽疫亚种分离株序列进行同源性比对和遗传进化分析。结果显示,分离得到了一株革兰氏阳性链球菌,将其命名为马链球菌兽疫亚种ZMSY15-1。药物敏感性试验结果表明,分离菌株对青霉素、磺胺嘧啶钠耐药,对其他14种药物均敏感。序列分析结果显示,马链球菌兽疫亚种ZMSY15-1与国内外不同动物源分离株SzM基因氨基酸同源性为56.0%～70.0%。遗传进化分析结果显示,这些菌株可分为4个群。马链球菌兽疫亚种ZMSY15-1与猪源分离株SzM蛋白的氨基酸同源性为59.9%,分别属于2个不同的群,其与美国马源分离株NH55426亲缘关系最近。本试验结果可丰富国内马源马链球菌兽疫亚种SzM基因的信息数据,为马链球菌兽疫亚种的致病机制研究和预防控制提供参考依据。

To understand the molecular evolution and mutation of SzM gene of Streptococcus equi subsp.zooepidemicus(S.zooepidemicus)from horse in Xinjiang and provide basis for the prevention and treatment of infectious disease,lymph gland samples from sick horse were collected for bacterium culture,biochemical identification,and drug sensitivity test was also tested.The SzM gene was amplified from genomic DNA of S.zooepidemicus isolate by PCR based on the primers designed according to the published sequence in GenBank.Then the amplified SzM gene was cloned,sequenced and analyzed,and phylogenetic tree was constructed.The results showed that the isolate was Gram-positive Streptococcus,which was named as S.zooepidemicus ZMSY15-1.Drug sensitivity test showed that S.zooepidemicus ZMSY15-1was resistant to penicillin and sul-fadiazine sodium salt,and sensitive to other 14 microbials.The amino acid homologies of SzM gene of ZMSY15-1with different strains at home and abroad were 56.0%to 70.0%.In addition,the phylogenetic analysis indicated that these test strains belonged to 4different clades,the ZMSY15-1isolate shared identities of 59.9% with swine isolates and they belonged to two different groups.The ZMSY15-1isolate was closely related to US horse NH55426.The results could enrich the information data of SzMgene of S.zooepidemicusin domestic horses,and provide experimental data for the pathogenic mechanism and prevention control of S.zooepidemicus.