Pathogenic Characteristics of a Porcine Astrovirus Strain Isolated in China

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.

Coinfection and Genetic Characterization of Porcine Astrovirus in Diarrheic Piglets in China From 2015 to 2018

“…A previous surveillance study conducted by our group found a high percentage of coinfection among diarrheic piglets (9). PAstV, which has been identified as an important agent of diarrhea (10), and frequently presents as a coinfection with other porcine pathogens (3,5,6,9,11). However, data regarding coinfections with PAstV in diarrheic piglets in China are limited.…”

Comprehensive Analysis of Codon Usage on Porcine Astrovirus

“…The results of the preferred codons were consistent with those of the nucleotide composition analysis. 6) codons, respectively. PCA results showed that the first two principal axes accounted for 41.9% and 24.6% of the total variation of RSCUs ( Figure S1).…”

“…PAstV-3 is found in tissues from the central nervous system of piglets and sows with encephalomyelitis and neural necrosis [4,5]. Infection of piglets with PAstV-1 could cause mild diarrhea, growth retardation, and damage to the villi of the small intestinal mucosa [6]. PAstV-4 was detected in the nasal swabs [7] and the feces of pigs [8,9].…”

Establishment of a Multiplex RT-PCR Method for the Detection of Five Known Genotypes of Porcine Astroviruses

“…In the recent decade, with the aid of improved sequencing techniques such as high-throughput sequencing, increasing novel clades of astroviruses have been discovered ( 31 ). For quite some time, PAstV was considered as a low-pathogenic virus causing a short-term mild diarrhea ( 32 , 33 ). However, emerging cases of PAstV associated enteritis or polioencephalomyelitis were reported and attracted public attention in recent years ( 8 , 9 , 34 , 35 ).…”

“…In this study, the infection rates of pigs at lactation and nursery stage were also higher than those of grown pigs ( Table 2 ). Pathogenic studies have shown that PAstV infection could cause diarrhea and growth retardation, which could lead to economic losses and cannot be ignored in large-scale pig industries ( 32 , 33 ). Moreover, coinfections of PAstV with other swine viruses were also reported, which pointed out that PAstVs were more intended to co-infect with other viruses, and immunosuppressive viruses such as CSFV could benefit from the replication of PAstV ( 13 , 14 , 43 ).…”