王召贺 陈波 徐高原 张华伟 郝根喜 潘建刚 周明光

摘要 为了解猪链球菌血清9型菌株KQ-1株、KQ-2株的生物特性，对其进行了菌种鉴定、生長曲线绘制、毒力因子鉴定和小鼠致病性试验。首先采用革兰氏染色、PCR鉴定的方法对2株菌进行菌种鉴定，然后利用猪链球菌的主要毒力基因mrp、epf、sly、gadph、orf2、fbps、89k的引物对2株菌的毒力基因进行鉴定;将2株菌在TSB培养基（含10%新生牛血清）中进行培养，绘制其生长曲线，初步了解这2株菌的生长特性;选取45只健康的昆明鼠注射2株菌的菌液，进行致病性试验，了解其致病性。结果显示，KQ-1株、KQ-2株革兰氏染色呈阳性，PCR鉴定结果为猪链球菌血清9型;2株菌均在37 ℃培养6 h时菌液密度达到最高值。对2株菌毒力基因的鉴定结果如下：KQ-1株的基因型为mrp+/epf-/sly+/gadph+/orf2-/fbps-/89k-，KQ-2株的基因型为mrp-/epf-/sly-/gadph+/orf2+/ fbps-/ 89k-;对2株菌的小鼠致病性试验表明，2株菌均为强毒株。

关键词 猪链球菌;血清9型;毒力基因;致病性试验

中图分类号 S855.1+1文献标识码 A

文章编号 0517-6611（2021）10-0092-06

doi：10.3969/j.issn.0517-6611.2021.10.025

开放科学（资源服务）标识码（OSID）：

Biological Characteristics Analysis of Two Streptococcus suis Serotype 9 Strains

WANG Zhao-he，CHEN Bo，XU Gao-yuan et al （Wuhan Keqian Biology Co.，Ltd.，Wuhan，Hubei430000）

Abstract In order to understand the biological characteristics of Streptococcus suis serotype 9 strains（KQ-1 and KQ-2），the identification of strains and their virulence genes，drawing of growth curves，mouses pathogenicity test were conducted.Those two strains were identified by Gram staining and PCR，then the primers of the main virulence genes （mrp，epf，sly，gadph，orf2，fbps，89k） of S.suis were used to identify the virulence genes of the two strains.The two strains were cultured in TSB medium （containing 10% newborn calf serum），and their growth curves were drawn to get a preliminary understanding of the growth characteristics of the two strains.45 healthy Kunming rats were injected with two strains of bacteria for the pathogenicity test to understand their pathogenicity.The results showed that the Gram staining results of KQ-1 strain and KQ-2 strain were positive，they were identified as S.suis serotype 9 strains by PCR identification.The bacterial liquid density of the two strains both reached the peak at 6 h when cultured at 37 ℃.The results of virulence factors of the two strains showed that the genotype of KQ-1 strain was mrp+/epf-/sly+/gadph+/orf2-/fbps-/89k-，while that of KQ-2 strain was mrp-/epf-/sly-/gadph+/ orf2+/fbps-/89k-.The results of pathogenicity test on mice showed that the two strains were highly virulent.

Key words Streptococcus suis;Serotype 9;Virulence genes;Pathogenicity test

猪链球菌（Streptococcus suis）是一种革兰氏阳性菌，能引起感染猪只的脑膜炎、关节炎、败血症等症状，属于人畜共患病原体[1]。1998和2005年，在江苏南通和四川资阳等地发生猪链球菌感染暴发事件，并引发工作人员感染，造成了重大的经济损失和人员伤亡[2-3]。根据荚膜多糖抗原性的不同，猪链球菌可分为35个血清型，即血清1～34型和1/2型。在世界范围内以血清2型最为流行，其次是血清9型、3型等，血清2型也是目前研究最多的血清型，而关于其他血清型的研究较少[4]。目前我国虽然没有血清9型的暴发事件发生，但经常从病猪体内分离出血清9型菌株，且近年来血清9型有扩大流行趋势[5-7]，需要引起相关研究人员和养殖业从业人员的注意。……