禽沙门菌诱导宿主免疫应答的特性

Characteristics of immune response induced by avian Salmonella

摘要:

沙门菌病（Salmonellosis）是全世界最普遍的食源性疾病之一，不仅对养殖业造成经济损失，还对人类安全构成威胁。禽沙门菌感染肠道后，可诱导肠上皮细胞表达多种TLRs和炎症反应的发生，在分泌的趋化因子作用下免疫效应细胞迁移到感染部位。细菌通过肠上皮细胞屏障后被巨噬细胞或树突状细胞吞噬，其中巨噬细胞是沙门菌的主要定殖场所。天然免疫系统将抗原递呈给淋巴细胞后，机体能够在2-3周内通过以Th1为主的免疫应答清除在肠道和深层组织中的沙门菌。而宿主特异性血清型鸡白痢沙门菌从肠道侵入后，在肝脾和其他器官中定殖，进而引发全身感染。早期感染阶段不会引起肠道炎症反应，主要诱导以Th2为主的免疫应答，而Th1型应答相对较弱，有利于鸡白痢沙门菌在机体内的持续存在和感染。本文围绕禽沙门菌的致病机理和免疫应答特性进行阐述，尤其对鸡白痢沙门菌免疫逃逸和持续载菌的特性进行深入分析，为禽沙门菌病的防控提供新靶标和新见解。

Abstract:

Salmonellosis is one of the most widespread food-borne diseases throughout the world, not only causes economic losses to the breeding industry, but also poses a threat to human health. Avian Salmonella enters the small intestine where infection can be established, inducing intestinal epithelial cells express a number of TLRs and inflammation. These lead to the expression of chemokines that attract immune effector cells to the sites of infection. Following translocation across the intestinal epithelial barrier, bacteria are phagocytosed by cells such as macrophages and DCs, macrophages are its preferred cell type. The adaptive immune response is stimulated by the innate immune system through antigen presentation to lymphocytes. Adaptive immunity can clear infection within 2-3 weeks following infection by a Th1 dominated response in the gut and deeper tissues. In contrast, avian systemic salmonellosis caused by the host-adapted serovar S. Pullorum is characterized by invasion from the intestine with multiplication in the spleen, liver and other organs. The stage of infection resulted in little inflammation in vivo or in vitro. S. Pullorum tends to induce an immune response that more closely resembled the Th2 response in mammals and would allow S. Pullorum to establish an intracellular carriage evading Th1-mediated clearance. This review compared the pathogenesis and immune response characteristics of Salmonella, especially the mechanisms by which S. Pullorum evades host immunity and produces the persistent carrier state. Finally, it will be helpful to provide new targets and new opinions for the prevention and control of avian salmonellosis.