PEDV通过鼻腔入侵引起仔猪肠道致病机制的研究

Porcine epidemic diarrhea (PED) is a highly contagious and causes severe diarrhea in suckling piglets. The causative agent, porcine epidemic diarrhea virus (PEDV), spreads rapidly among farms. Although PEDV infection among pigs occurs predominantly by the fecal-oral route, airborne transmission had been also considered as a potential route for PEDV dissemination. The mechanism by which PEDV entry to intestinal epithelium through respiratory route will be well investigated in this project. Firstly, an in vitro co-culture model consisted by porcine nasal respiratory mucosal epithelium and dendritic cell (DC) is established and the mechanism of PEDV acquired by M cells and DC will be studied. Then the mechanism for DC carrying PEDV and transmitting the virus to lymphocyte is investigated. Moreover, intestinal epithelium and lymphocyte are co-cultured in vitro and the mechanism for PEDV infecting the intestinal epithelium from basolateral surface will be also illustrated. Finally, a further verifying research about PEDV infecting intestinal epithelium via respiratory route will be performed by PEDV challenging experiment in piglet. The results will provide a new perspective on the tropism of PEDV pathogenesis and could contribute the control for PED infection.

猪流行性腹泻（Porcine epidemic diarrhea，PED）是由猪流行性腹泻病毒（Porcine epidemic diarrhea virus，PEDV）引起的急性、高度接触传染性消化道疾病。PED传播快、流行广，不仅通过粪-口途径传播，还能通过呼吸道传播。本项目针对PEDV通过呼吸道入侵经淋巴循环和血液循环引起肠黏膜上皮致病机制展开一系列研究。首先构建猪鼻腔黏膜上皮与树突状细胞（dendritic cell，DC）气液共培养模型，研究M细胞和DC摄取PEDV的机制；其次研究DC携带PEDV并将病毒传递给淋巴细胞的机制；随后建立猪肠上皮细胞与淋巴细胞共培养模型，深入研究携带PEDV的淋巴细胞从基底侧传递病毒并感染小肠黏膜上皮的机制；最后应用动物试验进一步验证PEDV通过呼吸道入侵引起仔猪肠黏膜上皮的致病机理。本项目的研究结果将为我国有效预防和控制PED的发生提供重要的理论。

猪流行性腹泻（Porcine epidemic diarrhea，PED）是由猪流行性腹泻病毒（Porcine epidemic diarrhea virus，PEDV）引起的急性、高度传染性消化道疾病。PED具有传播快、流行广和致死率高等特点，自2011年起该病对全球的养猪业造成了毁灭性的打击。尽管PEDV公认的传播方式是粪-口传播，但最近越来越多的研究表明该病毒也能通过空气传播并能够进入仔猪鼻腔，因此本研究提出PEDV能够经鼻腔引起仔猪肠道发病的假说。为验证这一假说，首先通过喷鼻PEDV攻毒5日龄仔猪，观察仔猪的临床症状，结果表明喷鼻感染60 h后仔猪出现典型的PED样腹泻症状，并有大量病毒定殖于小肠上皮中。于是本研究将围绕这一现象，具体探讨PEDV经鼻腔黏膜入侵后经体内扩散，最终引起仔猪肠道发病的相关机制。试验结果表明PEDV能够通过鼻腔黏膜下的树突状细胞（Dendritic cells，DCs）的主动摄取进入鼻腔黏膜固有层，随后摄取病毒的DCs能够进入附近的引流淋巴结并将病毒传递给T淋巴细胞，进一步携带病毒的T淋巴细胞能够进入肠道黏膜固有层并通过直接接触传递病毒给肠道上皮细胞。本研究证明了PEDV能够经鼻腔黏膜入侵引起仔猪的肠道感染，并对其从入侵部位到致病部位的体内扩散机制进行了研究。本文的研究结果将为我国有效预防和控制PED的发生提供重要的理论依据。