Pathogenic Characteristics of a Porcine Astrovirus Strain Isolated in China.

Qingli Fang,Qingping Wu,Qinting Dong,Ying Chen,Minli Cen,Siying Liang,Cui Wang,Huan Liu,Kang Ouyang,Weijian Huang,Zuzhang Wei,Yingyi Wei

doi:10.3390/v11121156

Qingli Fang, Qingping Wu + Show 10 more

Open Access

https://doi.org/10.3390/v11121156

Copy DOI

Journal: Viruses	Publication Date: Dec 13, 2019
Citations: 28	License type: CC BY 4.0

Affiliation: Guangxi University

Abstract

Astroviral infection is considered to be one of the causes of mammalian diarrheal diseases. It has been shown that astrovirus infections cause varying degrees of diarrhea in turkeys and mice. However, the pathogenesis of porcine astrovirus is unknown. In this study, the virulence of a cytopathic porcine astrovirus (PAstV) strain (PAstV1-GX1) isolated from the PK-15 cell line was tested using seven-day-old nursing piglets. The results showed that PAstV1-GX1 infection could cause mild diarrhea, growth retardation, and damage of the villi of the small intestinal mucosa. However, all the above symptoms could be restored within 7 to 10days post inoculation (dpi). To evaluate the innate immunity response of PAstV in vivo, the alteration of inflammatory cytokine expression in piglets infected with PAstV1-GX1 was determined using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). The mRNA expression levels of the IFNβ and ISG54 were found to be significantly elevated in virus-infected piglets. In contrast, expression of IFNλ was downregulated in piglets infected with PAstV1-GX1. In addition, the mRNA expression of the tight junction protein 1 and 2 and zonula occludin 1, which are associated with the intestinal barrier permeability, were affected after PAstV1 infection. The present study adds to our understanding of the pathogenic mechanism of PAstV and has established an animal model for further study of pig astrovirus infection.

Highlights

Porcine astrovirus (PAstV) is single-stranded positive sense, non-enveloped RNA virus with a diameter of about 28–30 nm [1]
There was no significant difference in body temperature between the two groups throughout the experimental period
The results demonstrated that the mRNA expression of tight junction protein 1 (TJP1) in challenged pigs was significantly downregulated in the colon at 2 dpi and in the rectum at 4 dpi, respectively

Summary

Introduction

Porcine astrovirus (PAstV) is single-stranded positive sense, non-enveloped RNA virus with a diameter of about 28–30 nm [1]. Based on the phylogenetic analysis of the amino acid sequences of ORF2, PAstVs are divided into five genotypes (PAstV1–PAstV5) [4,5,6,7]. The genome length of PAstV is 6.4–7.3 kb and it contains three continuous open reading frames (ORFs), named ORF1a, ORF1b, and ORF2. ORF1a and ORF1b are situated at the 50 -end of the genome and they encode a nonstructural protein (nsp) named nsp1ab, which encompasses viral nonstructural serine protease and RNA polymerase, respectively. ORF2 is located at the 30 -end of the genome and encodes the viral capsid protein. The genome contains a 50 untranslated region (UTR), a 30 UTR, and a poly-A tail [8]

Methods

Results

Discussion

Conclusion