Isolation and Pathogenicity of a Chinese Porcine Astrovirus Type 5 Strain HNPDS-01 and Its Influence on Cecum Microbiota in Piglets

Abstract

Astroviruses have frequently been found in mammals and poultry, but only a few have been successfully isolated for extensive research. Here, we isolated a strain of porcine astrovirus type 5 (PAstV 5) on LLC-porcine kidney (LLC-PK) cells, from the intestinal contents of diarrhea piglets, namely PAstV 5-HNPDS-01. The complete genome sequence length of this strain was 6,419 nt, which has 77.2%–91.1% nucleotide homology with other PAstV 5 strains and 45.0%–50.0% nucleotide homology with other mammalian astroviruses. The recombination analysis indicated that the recombination events were occurred in ORF 2 region (4,444–5,323 nt) in PAstV 5-HNPDS-01 strain. Subsequently, the pathogenicity of PAstV 5-HNPDS-01 was evaluated in 5-day-old piglets. It showed that the PAstV 5-HNPDS-01 could cause mild diarrhea, growth retardation, minor damage to intestinal villi clinically. Meanwhile, PAstV 5-HNPDS-01 infection could affect the microbiota diversity and composition of cecum in piglet from phylum to genus level. After infected with PAstV 5, there was a significant downregulation of beneficial bacteria, including Faecalibacterium, Bacteroides, Lactobacillus, and Prevotella, while harmful bacteria such as Subdoligranulun showed a significant upregulation. These results provided a research basis for pathogenic mechanisms, vaccine development, and beneficial symbiotic bacteria development for PAstV 5 infection.