SteE对鸡白痢沙门氏菌在雏鸡体内定植及宿主免疫反应的影响

Effect of SteE on the Colonization and Host Immune Response of Salmonella Pullorum in Chicken

试验旨在研究效应蛋白SteE对鸡白痢沙门氏菌在雏鸡体内的定植及宿主免疫反应的影响。试验分别使用鸡白痢沙门氏菌(Salmonella Pullorum)、鸡白痢沙门氏菌steE缺失株和PBS灌服2日龄雏鸡,在雏鸡感染后的12 h、24 h、36 h、2 d、3 d、5 d、7 d取脏器涂板观察细菌定植情况,并采用石蜡切片、HE染色和qRT-PCR方法研究感染后3 d时雏鸡肝脏和脾脏的病理变化和炎性因子表达情况。结果显示:与鸡白痢沙门氏菌感染组相比,鸡白痢沙门氏菌steE缺失株感染组雏鸡脏器细菌载量降低,且在感染后3 d时差异显著(P<0.05),但心脏未出现差异。鸡白痢沙门氏菌感染组和鸡白痢沙门氏菌steE缺失株感染组雏鸡肝脏均出现增生性结节,且前者结节数量多、面积大。鸡白痢沙门氏菌steE缺失株感染组雏鸡脾脏内巨噬细胞较鸡白痢沙门氏菌感染组少、动脉周围组织淋巴鞘面积小。但对照组雏鸡脏器未发现细菌定植和明显病理变化。与对照组相比,鸡白痢沙门氏菌感染组和鸡白痢沙门氏菌steE缺失株感染组雏鸡肝脏和脾脏中炎性因子的表达均升高,但鸡白痢沙门氏菌steE缺失株感染组与鸡白痢沙门氏菌感染组相比,肝脏和脾脏中白细胞介素-10(IL-10)的表达量前者显著低于后者(P<0.05),白细胞介素-12(IL-12)、γ-干扰素(IFN-γ)的表达量显著高于后者(P<0.05)。研究表明,鸡白痢沙门氏菌效应蛋白SteE可增强细菌的定植、加重鸡肝脏和脾脏的病理变化、促进抗炎细胞因子的表达。

The aim of the experiment was to study the effect of effector protein SteE on colonization of Salmonella Pullorum in chickens and the host immune response.The experiment used Salmonella Pullorum,Salmonella Pullorum steE mutant,and PBS ga-vage for 2-day-age chickens with oral administration,the bacterial colonization was observed by taking organ plate observations at 12 h,24 h,36 h,2 d,3 d,5 d,and 7 d after infection.And paraffin sections,HE staining,and qRT-PCR methods were used to study the pathological changes and inflammatory factor expression in the liver and spleen of chickens at 3 days after infection.The results showed that compared with the Salmonella Pullorum group,the bacterial load in the organs of Salmonella PullorumΔsteE group was lower,and the difference was significant at 3 days(P<0.05),but there was no difference in the heart.Hyperplastic nodules were found in the livers of chickens in both Salmonella Pullorum group and Salmonella PullorumΔsteE group,with more nodules and larger ar-eas in the former.The number of macrophages in the spleen of chickens in Salmonella PullorumΔsteE group was lower than in Salmo-nella Pullorum group,and the area of lymphatic sheath around the artery was smaller.However,no bacterial colonization or obvious pathological changes were found in organs of the control group.Compared with the control group,the expression of inflammatory fac-tors in the liver spleen of chickens in both Salmonella Pullorum group and Salmonella PullorumΔsteE group increased.However,the expression of interleukin-10(IL-10)in liver and spleen of chickens in Salmonella PullorumΔsteE group were significantly lower than those in Salmonella Pullorum group(P<0.05),while the expression of interleukin-12(IL-12)andγ-interferon(IFN-γ)was sig-nificantly higher than those in the latter(P<0.05).The results indicated that the effector protein SteE of Salmonella Pullorum could enhance bacterial colonization,exacerbate pathological changes in the liver and spleen of chickens,and promote the expression of an-ti-inflammatory cytokines.