Identification of a novel astrovirus from intestinal tissue of a donkey foal with severe diarrhea in China

Abstract

A: Genomic organization of selected astroviruses in representative host species, including mink astrovirus 1 (MAstV-1), human astrovirus VA1 (HAstV-VA1), human astrovirus 8 (HAstV-8), human astrovirus MLB1 (HAstV-MLB1), ovine astrovirus 1 (OAstV-1), duck astrovirus C-NGB (DAstV-C-NGB), avian nephritis virus 1 (ANV-1), and turkey astrovirus 1 (TAstV-1). B: Overview of genome structures of DAstV-1. ORF1a, ORF1b, and ORF2 are marked in green, brown, and dark-blue, respectively. Transmembrane domains, trypsin-like peptidase domain, RNA-dependent RNA polymerase, and capsid protein precursor are marked in yellow, gray, orange, and light blue, respectively. Blue graph shows coverage of DAstV-1 reads. C: Secondary structure of conserved stem-loop II motif at 3′ end of DAstV-1 genome. D: Alignment of RNA sequences of stem-loop II motif at 3′ end of DAstV-1 and different viruses, showing high similarity with DAstV-1. Highly conserved part is marked in red. E–G: Phylogenetic relationships between DAstV-1 from this study and other astrovirus species based on amino acid sequence of capsid protein (E), ORF1a (F), and ORF1b (G). Optimal models were predicted using IQ-TREE 2, and trees were constructed using maximum-likelihood method, with branch scale bar shown as 0.7, 0.3, and 0.3 substitutions per site, respectively. Mamastrovirus and Avastrovirus genera of family Astroviridae are distinguished by different background colors (blue and orange, respectively). Novel DAstV-1 is marked in red and others are marked in black. Genogroups are listed in different colors on the right, and GenBank accession numbers are listed on the left.