猪链球菌7型CD1小鼠动物病理模型的建立及评价

Establishment and evaluation of pathologic model of CD1 mice infected with streptococcus suis serotype 7

目的为研究猪链球菌7型对CD1小鼠的致病性,探究CD1小鼠作为猪链球菌7型动物感染模型的可行性。方法采用猪链球菌7型广东分离株以腹腔接种方式感染CD1小鼠,通过临床症状观察、LD_(50)测定、剖检病理观察、肝脑组织切片观察、细菌鉴定及组织脏器细菌载量检测,建立CD1小鼠动物病理模型。结果感染后的CD1小鼠发病情况呈现良好的规律性和重复性,发病CD1小鼠在临床症状、剖检病理变化、组织损伤与以往研究猪链球菌2型、9型感染小鼠实验结果基本一致,同时也与猪自然发病相似。感染小鼠血液、心、肝、脾、肺、肾和脑组织均能分离到活细菌,回收细菌与原细菌一致,组织脏器细菌载量检测表明心脏细菌载量最高,其次依次是肝、肾、脾、肺、血液,脑中细菌载量最低。结论本实验猪链球菌7型菌株可导致CD1小鼠败血症和脑部炎症,导致组织损伤而发病死亡,因此CD1小鼠对实验菌株敏感,可作为猪链球菌7型的感染动物模型。

Objective To study the pathogenicity of Streptococcus suis type 7 in CD1 mice and to explore the feasibility of CD1 mice as an animal infection model of Streptococcus suis type 7.Methods CD1 mice were infected with Streptococcus suis type 7 isolated from Guangdong Province by intraperitoneal inoculation.The pathological model of CD1 mice was evaluated by the observation of clinical symptoms,pathological autopsy,histopathological examination of liver and brain tissue sections,determination of LD_(50),and identification of bacteria and detection of bacterial load in tissues and organs.Results The pathological incidence of infected CD1 mice showed good regularity and repeatability.The clinical symptoms,pathological changes and tissue damage of infected CD1 mice were basically consistent with the previous experimental results of Streptococcus suis type 2 and 9 infection in mice and were similar to the natural disease of pigs.Live bacteria could be isolated from blood,heart,liver,spleen,lung,kidney and brain of infected mice,and the recovered bacteria were consistent with the original bacteria.The detection of bacterial load in tissues and organs showed that the bacterial load in heart was the highest,followed by liver,kidney,spleen,lung and blood,and the bacterial load in brain was the lowest.Conclusion In this study,we demonstrate that Streptococcus suis type 7 strain can cause sepsis and brain inflammation in CD1 mice,resulting in tissue damage and death.CD1 mice are sensitive to the experimental strain and can be used as an animal model of streptococcus suis type 7 infection.