Molecular epidemiology and viremia of porcine astrovirus in pigs from Guangxi province of China

Yifeng Qin,Weijian Huang,Kang Ouyang,Xunjie Li,Ying Chen,Zuzhang Wei,Fakai Li,Huan Liu,Qingli Fang

doi:10.1186/s12917-019-2217-x

Abstract

BackgroundPorcine astroviruses (PAstVs) are common in pigs worldwide. There are five distinct lineages with each lineage representing a different ancestral origin. Recently, multiple reports have demonstrated the evidence of extra-intestinal infection of PAstVs, but little is known about viremia.ResultsIn this study, a total of 532 fecal samples and 120 serum samples from healthy pigs were collected and tested from 2013 to 2015 in Guangxi province, China; of these 300/532 (56.4%) and 7/120 (5.8%) of fecal samples tested positive for PAstVs, respectively. Our study revealed that there was wide genetic diversity and high prevalence of the virus in the pig population. All five of the known PAstVs genotypes (1–5) prevailed in the pig population of Guangxi province and were distributed in all age groups of pigs, from suckling piglets to sows, with PAstV2 (47.7%), PAstV1 (26.2%) and PAstV5 (21.5%) seen predominantly. Phylogenetic analysis of partial ORF1b and partial capsid sequences from fecal and serum samples revealed that they were divided into the five lineages. Among these genotypes, based on partial ORF2 genes sequencing 23 strains were grouped as PAstV1, including 6 serum-derived strains, and were regarded as the causative agents of viremia in pigs.ConclusionsDue to the information regarding the types of PAstV in blood is limit. This is the first report for the presence of PAstV1 in blood and PAstV3 in the feces of nursery pigs of China. This study provides a reference for understanding the prevalence and genetic evolution of PAstVs in pigs in Guangxi province, China. It also provides a new perspective for understanding of the extra-intestinal infection of PAstVs in pigs.

Highlights

Porcine astroviruses (PAstVs) are common in pigs worldwide
Astroviruses (AstVs) belonging to the family Astroviridae was first identified by electron microscopy (EM) in fecal samples from children suffering with diarrhea in 1975 [1]
Detection of PAstVs in pig serum and fecal samples In this study, all the samples were tested for the existence of PAstVs by the nested Reverse transcriptase-polymerase chain reaction (RT-PCR) method

Summary

Introduction

Porcine astroviruses (PAstVs) are common in pigs worldwide. Astroviruses (AstVs) belonging to the family Astroviridae was first identified by electron microscopy (EM) in fecal samples from children suffering with diarrhea in 1975 [1]. AstVs are divided into two genera: Mamastrovirus and Avastrovirus, which contain 19 and 3 species, respectively [2]. AstVs are single-stranded positive-sense RNA viruses, about 28-30 nm in diameter, whose genome contain three open reading frames (ORFs), namely ORF1a, ORF1b and ORF2. ORF1a and ORF1b code for nonstructural proteins, a protease and a RNA-dependent. RNA polymerase (RdRp), respectively [3]. ORF2 codes for a highly divergent capsid protein which is formed in response to the immune pressure from the host [3]. The genome includes a 5ˊ-untranslated region (UTR), a 3ˊ-UTR and a poly-A tail

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