不同血清型猪链球菌对新西兰兔的致病性研究

Study on the Pathogenicity of Different Serotypes of Streptococcus suis to New Zealand Rabbits

【目的】探究不同血清型猪链球菌(Streptococcus suis,SS)在新西兰兔体内的分布规律及致病性差异,为猪链球菌病的防治提供参考。【方法】分别采用SS1 ZY194株、SS2 QH株、SS7 ZY188株感染新西兰兔,通过临床症状观察,HE染色分析病理组织变化;利用实时荧光定量PCR检测脏器载菌量;通过试剂盒检测血清与肝脏生化指标变化;利用ELISA检测相关炎症因子的表达水平。【结果】3个试验组中,SS2组新西兰兔的临床症状表现与脏器的病理变化程度最明显。试验组新西兰兔各脏器均载菌,其中SS2组各脏器载菌量高于SS1和SS7组,且脾脏是载菌量最高的器官。各试验组新西兰兔葡萄糖(GLU)、甘油三酯(TG)、总胆固醇(TCHO)、低密度脂蛋白(LDL)和尿酸(UA)含量极显著或显著高于对照组(P<0.01;P<0.05),SS2和SS7组新西兰兔高密度脂蛋白(HDL)含量极显著低于对照组(P<0.01)。各试验组新西兰兔谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、脂肪酶(LPS)含量及炎症因子IL-6、IL-1β、TNF-α的表达水平极显著或显著高于对照组(P<0.01;P<0.05),其中SS2组各指标的含量最高。【结论】不同血清型猪链球菌均可引起新西兰兔发病,其中SS2 QH株致病性最强。试验结果为猪链球菌病的致病机理研究提供借鉴,为临床防治该病提供理论基础。

【Objective】This study was aimed to investigate the distribution pattern and differences in pathogenicity of different serotypes of Streptococcus suis(SS)in New Zealand rabbits,so as to provide reference for the prevention and control of porcine streptococcal disease.【Method】In this study,New Zealand rabbits were infected with SS1 ZY194,SS2 QH and SS7 ZY188 strains,respectively,and the clinical symptoms were observed,the pathological tissue changes were analyzed by HE staining.The organ bacterial load was detected using Real-time quantitative PCR,the changes in biochemical indexes of serum and liver were detected by kit,and the expression of related inflammatory factors were detected by ELISA.【Result】The clinical symptoms and the degree of pathological changes in organs of New Zealand rabbits in SS2 group were the most obvious among 3 groups.All the organs of New Zealand rabbits in experimental groups were bacterial-carrying,and the bacterial load of organs in SS2 group was higher than that in SS1 and SS7 groups,and spleen was the organ with the highest bacterial load.The contents of glucose(GLU),triglyceride(TG),total cholesterol(TCHO),low density lipoprotein(LDL)and uric acid(UA)of New Zealand rabbits in experimental groups were extremely significantly or significantly higher than those in control group(P<0.01 or P<0.05),and the content of high density lipoprotein(HDL)of New Zealand rabbits in SS2 and SS7 groups were extremely significantly lower than that in control group(P<0.01).The contents of glutathione peroxidase(GSH-Px),superoxide dismutase(SOD)and lipase(LPS),and the expression of inflammatory factors IL-6,IL-1βand TNF-αof New Zealand rabbits in experimental groups were extremely significantly or significantly higher than those in control group(P<0.01 or P<0.05),and the levels of each index in SS2 group were the highest.【Conclusion】The different serotypes of Streptococcus suis could cause disease in New Zealand rabbits,among which the SS2 QH strain was the most pathogenic.The results provided a reference for the pathogenesis research on porcine streptococcal disease and a theoretical basis for clinical control.