浙江省9株猪链球菌2型分离株Cps2J全基因克隆与序列分析

Sequence analyses of the Cps2J gene in 9 strains of Streptococcus suis serotype2 isolated in Zhejiang province

目的了解浙江猪链球菌2型(SS2)分离株的分子基础及与国内外其他分离株的基因差异程度,确定Cps2J基因变异位点和频率,为该地区的猪链球菌防治提供科学依据。方法提取菌株DNA,应用聚合酶链反应(PCR)扩增菌株Cps2J基因全片段,克隆入质粒载体,纯化后采用ABI自动测序仪测定序列,并同国内外其他分离株的基因进行比较。结果扩增出9株菌株的Cps2J基因的完整开放阅读框(ORF)都为999bp,编码333个氨基酸,9株菌株Cps2J片段核苷酸高度同源,同源性在99.7%～100%;与国内外其他的SS2核苷酸的同源性为98.8%～99.0%,与猪链球菌1型的同源性只有56.8%～57.0%。结论9株浙江省猪链球菌2型分离株Cps2J基因序列非常保守,这些不同来源的菌株可能有相同的起源。

To explore the molecular characteristics of Streptococcus suis serotype 2（ss2）isolated in Zhejiang province by deciding the variation loci and its variation frequency of Cps2J gene.The total DNA of 9 strains of ss2 isolated in Zhejiang province were extracted and amplifed by PCR.Then,the Cps2J fragments were cloned into plasmid carrier and completely sequenced after purification.Finally,the sequence results of all 9 ss2 isolates were compared with those obtained by other studies around the world.It was found that the open reading fragments of Cps2J in 9 SS2 isolates encoding 333 amino acids were 999 bp in length.Comparisons of this region among ss2 isolates revealed a similarity of between 98.8% and 99.9%,while the homology to ss1 strains varied between 56.8% and 57.0%.Our study shows the sequences of complete Cps2J segment are fairly stable and all these 9 ss2 strains of different sources possibly have the same evolutionary origin.