Impact of TGEV infection on the pig small intestine

Abstract

BackgroundPig diarrhea causes high mortality and large economic losses in the swine industry. Transmissible gastroenteritis virus (TGEV) causes pig diarrhea, with 100% mortality in piglets less than 2 weeks old. No investigation has yet been made of the small intestine of piglets that survived infection by TGEV.MethodsIn this study, we evaluated the impact of TGEV infection on the small intestine of recovered pigs.ResultsHistological analyses showed that TGEV infection led to villi atrophy, and reduced villous height and crypt depth. The number of SIgA positive cells, CD3+T cells, and dendritic cells (DCs) in jejunum decreased after TGEV infection in vivo. In contrast, microfold cell (M cell) numbers and cell proliferation increased in infected pigs. TGEV infection also significantly enhanced the mRNA expression levels of cytokine IL-1β, IL-6, TNF-α, IL-10, and TGF-β. Additionally, lower gene copy numbers of Lactobacillus, and higher numbers of Enterobacteriaceae, were detected in mucosal scraping samples from TGEV-infected pigs.ConclusionsTGEV infection damages the small intestine, impairs immune functions, and increases pathogenic bacterial loading, all of which may facilitate secondary infections by other pathogens. These findings help quantify the impact of TGEV infection and clarify the pathogenic mechanisms underlying its effects in pigs.

Porcine transmissible gastroenteritis virus nonstructural protein 2 contributes to inflammation via NF-κB activation

“…Porcine TGEV is an enteropathogenic coronavirus that damages the small intestine and causes severe intestinal inflammation in piglets [23], and increased expression levels of the proinflammatory cytokines IL-1β, IL-6, and TNF-α have been detected in the jejunum [24]. Although TGEV-induced inflammation has been well-established, its exact underlying molecular mechanism is not understood.…”

EIF4A2 interacts with the membrane protein of transmissible gastroenteritis coronavirus and plays a role in virus replication

“…However, EIF4A2 had not been identified in intestinal cells in previous study, likely due to the different cell types used to construct the cDNA library. In vivo, TGEV replicates in the intestinal epithelial cells of susceptible animals, inducing cell injury, villi atrophy, as well as reduced villous height and crypt depth (Haelterman, 1972;Schwegmann and Herrler, 2006;Xia et al, 2018). Therefore, it is important to identify host proteins in the natural target cells of TGEV to study viral replication and pathogenesis.…”

Transmissible gastroenteritis virus targets Paneth cells to inhibit the self-renewal and differentiation of Lgr5 intestinal stem cells via Notch signaling

“…TGEV, together with the human coronaviruses (HCoV-NL63 and HCoV-229e), belongs to the genus Alphacoronavirus within the subfamily Coronaviridae 7 , which are single-stranded, positive-sense RNA viruses relevant in animal and human health 8 . Generally, TGEV causes transmissible gastroenteritis with high morbidity in pigs of all ages and as high as 100% mortality in newborn piglets, especially those within 2 weeks of birth 9 . Most notably, TGEV not only causes devastating impact on the global pig industry, but also is a potential threat to human health, as its infection suppresses protein translation in diverse human cells 10,11 .…”

“…The typical symptomatic pathway of TGEV infection is villous atrophy within 48 h, followed by crypt hyperplasia, concomitant with lethal watery diarrhea, and ultimately severe dehydration in piglets until death 12 . TGEV infection causes intestinal barrier dysfunction and disrupts intestinal homeostasis 9,13 , which could affect intestinal epithelium renewal. The intestinal homeostasis and intestinal epithelium renewal are normally sustained by fast-cycling stem cells located around the base of the crypt 14 .…”