羊链球菌CVCC55001、CVCC55002株对昆明小鼠的致病性研究

为研究羊链球菌CVCC55001、CVCC55002株对昆明系(KM)小鼠的致病性，使用羊链球菌CVCC55001、CVCC55002株分别对昆明小鼠进行毒力测定，观察临床和剖检症状，对死亡小鼠进行细菌分离培养，并对典型菌落进行形态、生化特性以及PCR鉴定。毒力测定结果显示CVCC55001对于昆明小鼠的最小致死剂量为9 CFU,CVCC55002对于昆明小鼠的最小致死剂量为11 CFU。感染羊链球菌死亡小鼠主要剖检症状为肝脏出血、肠道液化性坏死、脾脏肿大，病理变化为肝细胞出现大量坏死、肠道黏膜层广泛自溶、脾脏组织广泛坏死出血。本研究建立了羊链球菌CVCC55001、CVCC55002株的昆明小鼠攻毒感染模型，确定了最小致死剂量，对羊链球菌感染和致病性研究展开初步探索，为疫苗研究及评价提供了平台支撑。

Establishment of Mouse Infection Model of Streptococcus ovis CVCC55001 and CVCC55002 Strains

In order to study the pathogenicity of CVCC55001 and VCC55002 strains to KM mice. The virulence of CVCC55001 and CVCC55002 strains in KM mice was determined. The clinical and autopsy symptoms were observed, the bacteria of dead mice were isolated and cultured. The typical colonies were conducted on morphological, biochemical and PCR identification. The toxicity test showed that 1 MLD of CVCC55001 to KM mice was 9 CFU, and 1 MLD of CVCC55002 to KM mice was 11 CFU. The main autopsy symptoms of mice infected with CVCC55001 and VCC55002 were liver bleeding, intestinal liquefaction necrosis, and splenomegaly. The pathological changes included extensive necrosis of liver cells, extensive autolysis of the intestinal mucosal layer, and extensive necrosis and bleeding of spleen tissue. This study established mice model infected with CVCC55001 and CVCC55002 strains, and the minimum lethal dose was determined. The preliminary exploration of Streptococcus ovis infection and pathogenicity research were carried out, which were providing a support for vaccine research and evaluation.