广西部分地区猪链球菌血清型及其毒力因子流行性调查分析

Investigation on the Prevalence of Serotypes and Virulence Factors of Streptococcus suis in Some Areas of Guangxi

为探究广西部分地区猪链球菌(Streptococcus suis,SS)流行菌株主要血清型及毒力因子分布情况。本试验于2018年1月至2018年6月对从多个猪场采集到的116份疑似链球菌感染的组织病料(脑、肺脏、淋巴结等)进行病原菌检测,采用细菌分离鉴定、形态学观察及PCR扩增等方法对病原菌及其血清型和部分毒力因子进行鉴定。结果显示,116份样品共分离到链球菌32株,阳性率为27.59%(32/116),其血清型主要以SS2和SS9为主,分离率分别为40.63%(13/32)和43.75%(14/32),其他血清型为15.63%(5/32);毒力因子检测结果表明:SLY、MRP、EPF以及SBP2′因子的检出率分别为:81.25%(26/32)、59.38%(19/32)、50.00%(16/32)和71.88%(23/32)。32株链球菌中以SLY^+MRP^+EPF^+SBP2′^+(13株)、SLY^+MRP^-EPF^-SBP2′^-(5株)、SLY^+MRP^+EPF^-SBP2′^+(5株)为主要的毒力基因型,其中SS2均能检测出3个或3个以上的毒力因子。玉林、柳州市主要分布SS9型,南宁、百色市主要分布SS2型;广西不同地区毒力因子的分布情况存在差异且不同血清型或同一血清型的链球菌毒力因子的分布情况也各不相同,其中SS2携带的毒力因子检出率明显高于其他血清型。该研究可为今后猪链球菌疫苗及致病机理研究提供理论依据,为广西地区猪场链球菌血清型疫苗选择提供指导。

To investigate the distribution of major serotypes and virulence factors of Streptococcus suis(SS)strains in parts regions of Guangxi,116 samples of suspected streptococcal infections(brain,lung,lymph nodes,etc.)collected from different swine farms from January to June in 2018 were examined in this study.The serotypes and some virulence genes were identified by bacterial isolation,morphological observation,PCR amplification.The positive rate of Streptococcus suis in 116 samples was 27.59%(32/116).The main serotypes of positive samples were SS2(40.63%,13/32)and SS9(43.75%,14/32),and other serotypes accounted for 15.63%(5/32).The test results of virulence factors demonstrated that the detection rates of SLY,MRP,EPF and SBP2′factors were 81.25%(26/32),59.38%(19/32),50.00%(16/32)and 71.88%(23/32),respectively.Among the 32 strains of Streptococcus suis,SLY^+MRP^+EPF^+SBP2′^+(13 strains),SLY^+MRP^-EPF^-SBP2′^-(5 strains)and SLY^+MRP^+EPF^-SBP2′^+(5 strains)were the main virulence genotypes.And SS2 could be detected three or more virulence genes.SS9 was the prevalent type in Yulin and Liuzhou.SS2 was the prevalent type in Nanning and Baise.It was discovered that there were differences in the distribution of virulence factors in the four regions of Guangxi.The distribution of streptococcal virulence factors in different serotypes or the same serotype was different,and the detection rate of virulence gene of SS2 was higher than other serotypes.This study could provide a theoretical basis for the future research of Streptococcus suis vaccine and pathogenesis,and provide guidance for the selection of serotypes of Streptococcus suis vaccine in Guangxi.