Transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhea virus (PEDV) are similar coronaviruses, causing diseases characterized by vomiting, diarrhea, and death from severe dehydration in piglets. Thus, they have caused huge losses to the swine-breeding industry worldwide. Nowadays, they are easily transmitted among the continents via vehicles, equipment, and cargo. Both viruses establish an infection in porcine enterocytes in the small intestine, and their spike (S) proteins play a key role in the virus-cell binding process under unfavorable conditions when the intestine with a low pH is filled with a thick layer of mucus and proteases. Sialic acid, proteases, and low pH are three main inducers of coronavirus infection. However, the details of how sialic acid and low pH affect virus binding to the host cell are not determined, and the functions of the proteases are unknown. This review emphasizes the role of three factors in the invasion of TGEV and PEDV into porcine enterocytes and offers more insights into Alphacoronavirus infection in the intestinal environment.

中文翻译：

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肠上皮细胞感染冠状病毒的三种主要诱因：唾液酸，蛋白酶和低pH。

传染性胃肠炎病毒（TGEV）和猪流行性腹泻病毒（PEDV）是相似的冠状病毒，可引起以呕吐，腹泻和仔猪严重脱水死亡为特征的疾病。因此，它们给全世界的养猪业造成了巨大损失。如今，它们很容易通过车辆，设备和货物在各大洲之间传播。两种病毒均会在小肠的猪肠上皮细胞中感染，当低pH值的肠中充满厚厚的粘液层时，它们的刺突（S）蛋白在不利条件下的病毒-细胞结合过程中起关键作用。蛋白酶。唾液酸，蛋白酶和低pH是冠状病毒感染的三种主要诱因。但是，尚不确定唾液酸和低pH如何影响病毒与宿主细胞结合的细节，蛋白酶的功能尚不清楚。这篇综述强调了三因素在TGEV和PEDV侵袭猪肠细胞中的作用，并提供了对肠道环境中冠状病毒感染的更多见解。