辽宁省猪链球菌流行株主要血清型毒力因子检测及其致病性

Virulence factor detection and pathogenicity of main serotype Streptococcus suis in Liaoning Province

为了解辽宁省猪链球菌流行菌株主要血清型毒力因子分布特征及致病性,依据猪链球菌属保守基因及血清型特异性基因,从辽宁地区采集猪链球菌疑似病例肺脏、肝脾、脑、关节液等样品进行猪链球菌及其血清类型鉴定;应用猪链球菌6种主要毒力因子特异性基因扩增检测方法,检测所分离到的不同血清类型猪链球菌的毒力因子分布情况,并应用小鼠攻毒试验和病理学技术对其致病性进行观察研究。结果显示:从辽宁地区采集的72个样品中共分离到23株猪链球菌,主要血清型有1,2,7型,其中SS1型4株,SS2型2株,SS7型5株。其余12株未确定血清型。SS1、SS2、SS7型阳性率分别为17.39%,8.69%,30.43%。毒力因子检测结果显示,上述6种毒力因子检出率分别为100%,66.6%,25%,16.7%,75.0%,58.3%,其中SS2均具备6种毒力因子,SS1、SS7和血清型阴性株猪链球菌均具有部分毒力因子,与SS2的差异毒力因子为epf。SS2可引起小鼠的急性败血症以及脑膜炎,SS1、SS7均可引起小鼠发病,但各器官的损伤则较轻。SS1、SS2、SS7脑内接种均可引起小鼠脑膜炎,炎症反应SS2最重,SS1次之,SS7最轻。

In order to understand the distribution characteristics and pathogenicity of the virulence factors of main serotype Streptococcus suis in Liaoning Province,according to the conservative genes and serotype-specific genes of Streptococcus,the suspected cases of Streptococcus suis from the lungs,liver,spleen,and brain,synovial fluid and other samples were used to isolate and identify Streptococcus suis and their serotypes.Six virulence factor-specific gene amplification assays for Streptococcus suis were used to detect the distribution of virulence factors in the different serotypes of Streptococcus suis,and the application of mouse challenge test and pathological techniques to observe its pathogenicity.The results showed that 23 strains of Streptococcus suis were isolated from 72 samples collected in Liaoning.The main serotypes were type 1,2 and 7 among which were SS1 type 4,SS2 type 2 and SS7 type 5 strains,respectively.The remaining 12 strains were not serotyped.The positive rates of SS1,2,7 were 17.39%,8.69% and 30.43%,respectively.The virulence factor test results showed that the detection rates of the above six virulence factors were 100%,66.6%,25%,16.7%,75%and 58.3%,respectively,of which SS2 had 6 virulence factors,SS1,SS7 and the serotype-negative strain of Streptococcus suis had partial virulence factors,and the differential virulence factor of SS2 was epf;SS2 could cause acute septicemia and meningitis in mice.SS1 and SS7 could cause disease in mice,but the injury of each organ was slight.Intracerebral injection of SS1,SS2,and SS7 could cause meningitis in mice,and inflammatory response caused by SS2 was the most important,followed by SS1,SS7 lightest.