【作者】 邢娟；

【导师】 柳纪省； 胡永浩；

【作者基本信息】 甘肃农业大学 ， 预防兽医学， 2010， 硕士

【摘要】 根据国外当前的多位点序列分型(multilocus sequence typing,MLST)法,我国分离的猪链球菌S. suis 98HAH33和05ZYH33株属于序列7(sequence type 7,ST7)型。但S. suis 98HAH33和05ZYH33在7个猪链球菌MLST基因序列上的基因分子特征却与MLST ST7型其它猪链球菌分离株的基因分子特征不相吻合。鉴于上述原因,本研究尝试建立一种新的分型方法,力求同一型内的菌株在ST和基因分子特征方面获得一致。本研究首先从基因组上随机选择6个保守的酶基因和1个CPS基因,截取其500-750bp的保守片段。由于相关研究认为GenBank上发表的S. suis 98HAH33和S. suis 05ZYH33基因组序列存在较多的错误,所以,我们首先对本课题保存的S. suis 98HAH33和S. suis 05ZYH33菌株上的相关基因测序,以求得到准确的测序结果。同时,从GenBank上下载S. suis BM407,S. suis P1/7,S. suis SC84相关序列。之后,按C76和C77组合,将其按6或7片段连接起来,通过DNASTAR软件MegAlign建立遗传树。该分型法对所得的8个分型图均表明,S. suis 98HAH33、S. suis 05ZYH33均应归属于MLST ST1型,分型结果与S. suis 98HAH33、S. suis05ZYH33的基因分子特征完全吻合。同时,本研究从甘肃省部分地区采集到的152份健康猪扁桃体分离猪链球菌,共分离到67株猪链球菌菌株,分离率约44%。对67株猪链球菌菌株所作的耐药性检测表明,全部猪链球菌分离株具有多重耐药性,最严重者,对22种抗生素中的16种抗生素产生耐药性。用我国致病性2型猪链球菌特有的89k毒力岛序列特异性引物对67株猪链球菌进行PCR鉴定,仅发现一株猪链球菌分离株能够扩增出该特异性片段,提示在该地区健康猪群中少数猪可能隐性感染致病性2型猪链球菌病。更多还原

【Abstract】 In previous research, two invasive Chinese strains, S. suis 98HAH33 and S. suis 05ZYH33 were clustered into MLST ST7. However, the molecular characteristic of these two strains is inconsistent with other strains in MLST ST7. In this research, six housekeeping gene and CPS fragments of five invasive S. suis strains was obtained and the fragments were concatenated together as C76and C77. Then the concatenated sequences were used for phylogenetic tree analysis using DNA star software to resubtyping these popular S.suis isolates. Eight phylogenetic trees were obtained in this study and analysis of these trees revealed that the invasive S. suis strains isolated in China all belong to MLST ST1, and they all have a close relationship with S. suis 1/7. At the same time,they differed obviously from S. suis BM407 ,which was also belongd to MLST ST1. this result is in agree with the the molecular characteristic and genome analysis of these strains.In this research, 67 S. suis isolates was isolated from 152 of the tonsils from healthy slaughting pigs that was come from Wuwei, Lanzhou and Qingyang of Gansu province,PRC. Antimicrobial susceptibility test using disk diffusion showed that all of the bacterials isolated were multiple-antibiotic resistant, and for one isolates,it resistance to 16 of the 22 antibiotics detected. PCR was performed to investigat whether these isolates have a 89k pathogenicity island (PAI) 89K which was specific for Chinese SS2 virulent isolates or not.更多还原