猪源马链球菌兽疫亚种中国分离株类M基因特性分析

Analysis of the M-Like Gene of Streptococcus zooepidemicus Chinese Isolates from Pig

目的阐明国内不同区域猪源马链球菌兽疫亚种分离株类M基因的特性,为疫苗研制提供指导。方法利用PCR技术,扩增国内9省市从1974～2003年分离的9株马链球菌兽疫亚种类M基因,并进行克隆、测序及序列分析。结果发现7株类M基因长度为1137bp,含一个阅读框,CG-74-63和CP-0104株的长度分别为1143bp及1125bp。除1株关节炎分离株CP-0104外,引致败血症的8株菌类M基因的核苷酸同源性高达95.4%～99.9%,推导的相应氨基酸序列同源性高达92.1%～100%。9株猪源菌与马源菌株及人源菌株类M基因的核苷酸同源性分别为81.6%～87.0%、81.7%～91.8%。9株猪源分离株类M蛋白信号肽、C末端细胞锚定区的序列均高度同源;除CP-0104外,其余8株高变区高度同源。结论国内不同区域猪源马链球菌兽疫亚种分离株类M基因同源性高。

[ Objective ] In order to clarify the features of the M-like gene of Streptococcus equi subsp, zooepidemicus isolates from Chinese pig for directing the selection of vaccine isolate. [Method] The M-like genes were amplified from 9 isolates of Streptococcus equi subsp, zooepidemicus from Chinese pig by PCR and the M-like gene of each isolate was cloned, sequenced and analyzed. [Result] Nucleotide sequence analysis revealed one open reading frame in M-like protein gene of all isolates, with different length of 1 125 bp in CP-0104 isolate, 1 143 bp in CG-74-63 isolate, and 1 137 bp in the others. The nucleotide identifies of M-like genes among 9 isolates except CP-0104 isolate were higher than 95.4%, while the identities between isolate CP-0104 and the remaining 8 strains were 87.1%-88.3%. W60 strain, an equine origin isolate, shared identifies of 81.6%-87,0% with these 9 isolates from pig, and 25064 strain, a human origin isolate, shared identities of 81.7%-91,8% with these 9 isolates from pig, All the 9 isolates shared the common membrane anchor region and N-terminal signal peptide. [Conclusion] The M-like gene of 9 isolates of Streptococcus equi subsp, zooepidemicus from Chinese pig share high identity.