Isolation and Identification of Porcine Deltacoronavirus and Alteration of Immunoglobulin Transport Receptors in the Intestinal Mucosa of PDCoV-Infected Piglets.

Xiangchao Jia,Qingrong Xu,Shaoju Qian,Weida Zhang,Zili Li,Zitong Gao

doi:10.3390/v12010079

Xiangchao Jia, Qingrong Xu + Show 4 more

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https://doi.org/10.3390/v12010079

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Journal: Viruses	Publication Date: Jan 9, 2020
Citations: 36	License type: CC BY 4.0

Affiliation: Huazhong Agricultural University

Abstract

Porcine deltacoronavirus (PDCoV) is a porcine enteropathogenic coronavirus that causes watery diarrhea, vomiting, and frequently death in piglets, causing serious economic losses to the pig industry. The strain CHN-JS-2017 was isolated and identified by cytopathology, immunofluorescence assays, transmission electron microscopy, and sequence analysis. A nucleotide sequence alignment showed that the whole genome of CHN-JS-2017 is 97.4%–99.6% identical to other PDCoV strains. The pathogenicity of the CHN-JS-2017 strain was investigated in orally inoculated five-day-old piglets; the piglets developed acute, watery diarrhea, but all recovered and survived. CHN-JS-2017 infection-induced microscopic lesions were observed, and viral antigens were detected mainly by immunohistochemical staining in the small intestine. The neonatal Fc receptor (FcRn) and polymeric immunoglobulin receptor (pIgR) are crucial immunoglobulin (Ig) receptors for the transcytosis ofimmunoglobulin G (IgG), IgA, or IgM. Importantly, CHN-JS-2017 infected five-day-old piglets could significantly down-regulate the expression of FcRn, pIgR, and nuclear factor-kappa B (NF-κB)in the intestinal mucosa. Note that the level of FcRn mRNA in the intestinal mucosa of normal piglets is positively correlated with pIgR and NF-κB. At the same time, the expressions of FcRn, pIgR, and NF-κB mRNA are also positively correlated in infected piglets. These results may help explain the immunological and pathological changes associated with porcine deltacorononirus infection.

Highlights

Porcine deltacoronavirus (PDCoV) is an enveloped, single-stranded positive-sense (+ssRNA)virus belonging to the family Coronaviridae
To better understand in vivo immunological changes after PDCoV infection, we evaluated the effects of PDCoV on the pig intestinal gut polymeric immunoglobulin receptor (pIgR), FcRn, and NF-κB and their correlation by RT-qPCR, which may be related to the pathogenesis of PDCoV
Seven PDCoV-positive samples were inoculated onto LLC-PK cells; only one of the isolates showed visible cytopathic effect (CPE) at 36 h post-infection and was identified as PDCoV

Summary

Introduction

Porcine deltacoronavirus (PDCoV) is an enveloped, single-stranded positive-sense (+ssRNA)virus belonging to the family Coronaviridae. The clinical symptoms of PDCoV-infected piglets are like that of other porcine enteric pathogens, such as porcine epidemic diarrhea virus (PEDV) or transmissible gastroenteritis virus (TGEV), including diarrhea, vomiting, dehydration, and mortality [5]. All PDCoV-infected pigs had PEDV-like lesions characterized by thin and transparent intestinal walls and an accumulation of large amounts of yellow fluid in the intestinal lumen [6]. The PDCoV strain OH-FD22 causes thinning of the intestinal wall, resulting in yellow fluid accumulation in the intestinal cavity [7]. Several studies have reproduced similar clinically diarrheal symptoms in gnotobiotic and conventional pigs with isolated PDCoV strains [8,9,10,11]. PDCoV is enteropathogenic in pigs, and lesions are similar but relatively milder than PEDV [12]

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