Abstract

Porcine reproductive and respiratory syndrome (PRRS) induces respiratory disease and reproductive failure accompanied by gastroenteritis-like symptoms. The mechanism of intestinal barrier injury caused by PRRSV infection in piglets has yet to be investigated. An in vivo PRRSV-induced model was established in 30-day-old piglets by the intramuscular injection of 2 mL of 104 TCID50/mL PRRSV for 15 days. Observations of PRRSV replication and histology were conducted in the lungs and intestine, and goblet cell counts, relative MUC2 mRNA expression, and tight junction protein, proinflammatory cytokine, TLR4, MyD88, IκB and p-IκB expression were measured. PRRSV replicated in the lungs and small intestine, as demonstrated by absolute RT-qPCR quantification, and the PRRSV N protein was detected in the lung interstitium and jejunal mucosa. PRRSV infection induced both lung and gut injury, markedly decreased villus height and the villus to crypt ratio in the small intestine, and obviously increased the number of goblet cells and the relative expression of MUC2 mRNA in the jejunum. PRRSV infection aggravated the morphological depletion of tight junction proteins and increased IL-1β, IL-6, IL-8 and TNF-α expression by activating the NF-κB signalling pathway in the jejunum. PRRSV infection impaired intestinal integrity by damaging physical and immune barriers in the intestine by inducing inflammation, which may be related to the regulation of the gut-lung axis. This study also provides a new hypothesis regarding the pathogenesis of PRRSV-induced diarrhoea.

Highlights

  • Porcine reproductive and respiratory syndrome (PRRS) is a major immunosuppressive disease caused by porcine reproductive and respiratory syndrome virus (PRRSV) that threatens the pig industry worldwide

  • The piglets were seronegative for PRRSV antibodies at the beginning of the experiment according to a commercial PRRSV antibody rapid test card (Combined, China) and were confirmed to be free of PRRSV, porcine circovirus type 2 (PCV2), porcine parvovirus, pseudorabies virus, swine influenza virus and pig epidemic diarrhoea virus (PEDV) by the PCR testing of serum

  • Porcine reproductive and respiratory syndrome (PRRS) was identified in Europe in 1991 and emerged in the United States in 1992 [21, 22]; PRRS is a severe disease induced by porcine reproductive and respiratory syndrome virus (PRRSV)

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Summary

Introduction

Porcine reproductive and respiratory syndrome (PRRS) is a major immunosuppressive disease caused by porcine reproductive and respiratory syndrome virus (PRRSV) that threatens the pig industry worldwide. The major clinical characteristics of PRRS include respiratory disorders and reproductive failure, usually accompanied by gastroenteritis-like symptoms, such as diarrhoea and. The intestinal mucosal barrier plays an important role as the first barrier against pathogens in defending against harmful external factors and maintaining intestinal health. Zhao et al Vet Res (2021) 52:93 industry. Epithelial cells and their tight junctions create a barrier between the external environment and the host. Tight junction proteins commonly include zonula occludens (ZO), occludin and the claudin family proteins. Tight junction proteins limit intestinal epithelial cell permeability and protect mucosal cells from being exposed to bacteria and toxic macromolecules

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