猪流行性腹泻病毒诱导的猪肠道-乳腺-sIgA轴以及免疫机制探讨

猪的“肠道-乳腺-sIgA轴”免疫通路是指侵染猪的胃肠道病原通过胃肠道免疫可以激发乳腺产生sIgA；sIgA被初生仔猪摄取可以获得针对胃肠道病原的被动免疫保护。该免疫通路的反应动力模式涉及病原侵染、抗原提呈、淋巴细胞活化、淋巴细胞的肠道和乳腺归巢以及抗体分泌等诸多环节，受到病原毒力、母猪的妊娠阶段及免疫生理状态等众多因素影响。目前，猪流行性腹泻病毒（Porcine Epidemic Diarrhea Virus，PEDV）诱发的“肠道-乳腺-sIgA轴”的理论可以解释自然感染状态下哺乳仔猪获得的被动免疫保护，但根据这一概念所设计的疫苗和免疫方案并未取得满意效果。本文综述了PEDV感染和宿主免疫各个环节的研究现状，分析了影响PEDV免疫和肠道-乳腺-sIgA轴系反应的关键病原和宿主因素，提出了在轴系理论基础上应重视PEDV灭活疫苗以及特异IgG作用的建议。

Gut-mammary-sIgA axis and immunologic mechanisms induced by porcine epidemic diarrhea virus

Swine gut-mammary gland-sIgA (secretory IgA) axis is an immune route involving pregnant sows, which, once being infected or vaccinated by a gastroenteric route with an enteric pathogen can confer immune protection to their offspring against such pathogen through IgA contained in their colostrum or milk. The dynamic model of the axis is composed of complicated processes (e.g., invasion of pathogen, antigen presentation, activation of lymphocytes, homing of lymphocytes into intestine or mammary gland, and antibody secretion), which may be influenced or regulated by various factors such as virulence of pathogen, stage of pregnancy, and immune state of sow. The study about the axis model evoked by infection of porcine epidemic diarrhea virus (PEDV) can be used to explain the immune protection acquired through infection of virulent virus, while the design of vaccine and vaccination protocol depending on the model has not been satisfactory. This review summarized the studies about PEDV infection and host immune response and analyzed the key factors influencing the axis. it is suggested that more attention should be paid to functions of inactivated PEDV vaccine and specific IgG antibody though the immune axis, which is the most efficient mechanism for PEDV prevention.