广东、海南、福建3省罗非鱼链球菌病流行菌株PCR鉴定和PFGE基因型分析

PCR Detection and PFGE Genotype Analyses of Streptococcal Clinical Isolates from Tilapia in Guangdong,Hainan and Fujian Provinces

为研究近年来罗非鱼链球菌病流行菌株菌种与基因型变化信息,对广东、海南和福建3省罗非鱼主养区(共17个市县,93个养殖场)近4年的链球菌病流行菌株进行了分离,采用特异PCR方法对2009-2012年分离获得的流行菌株进行检测,并通过脉冲电场凝胶电泳(PFGE)对2009-2011年分离获得的流行菌株进行基因型分析。3省共分离到102株流行菌株,PCR鉴定结果显示均为无乳链球菌(Streptococcus agalactiae,S.agalactiae)。67株无乳链球菌PFGE图谱聚类显示产生A^G共7种PFGE带型,带型相似度在52.1%~100%之间。基因型A和D为广东优势菌群(93.48%,43/46),基因型F为海南优势菌群(66.7%,10/15),而福建6株分属于B、C和E共3个基因型。2009-2012年3省罗非鱼链球菌病流行菌种为无乳链球菌,流行菌株菌型较复杂,各省优势菌群存在较大差异,并且随时间发生变化。

In order to find out the information about the species of tilapia streptococcosis epidemic strains and their genotypic changes in recent years,the prevalent strains of tilapia streptococci from the main cultured areas of Guangdong,Guangxi,Hainan and Fujian provinces were detected through species specific PCR and pulse field gel electrophoresis （PFGE）.A total of 102 prevalent strains were isolated from 93 farms in 17 municipals of the three provinees between 2009 and 2012.All strains were identified as Streptococcus agalactiae.The results from PFGE revealed that the 67 strains isolated in 2009-2011 belonged to 7 distinctive PFGE types,in which similarity rate was 52.1％ -100 ％.The A and D were predominant genotypes in Guangdong （93.48 ％,43/46）,and in Hainan,most strains belonged to genotype F （66.7 ％,10/15） ; while only 6 strains from Fujian belonged to three different genotypes of B,C and E.Data suggested that the prevalent strains of tilapia streptococcal disease in three provinces was S.agalactiae between 2009-2012.However,the genotypes of epidemic strains from three provinces were quite different,and changed over time.