Detection and genetic characterization of Mamastrovirus 5 from Brazilian dogs

Abstract

Mamastrovirus 5 (MAstV5), belonging to the Astroviridae (AstV) family, previously known as canine astrovirus or astrovirus-like particles, has been reported in several countries to be associated with viral enteric disease in dogs since the 1980s. Astroviruses have been detected in fecal samples from a wide variety of mammals and birds that are associated with gastroenteritis and extra enteric manifestations. In the present study, RT-PCR was used to investigate the presence of MAstV5 in 269 dog fecal samples. MAstV5 was detected in 26% (71/269) of the samples. Interestingly, all MAstV5-positive samples derived from dogs displaying clinical signs suggestive of gastroenteritis, other enteric viruses were simultaneously detected (canine parvovirus, canine distemper virus, canine coronavirus, canine adenovirus and canine rotavirus). Based on genomic sequence analysis of MAstV5 a novel classification of the species into four genotypes, MAstV5a-MAstV5d, is proposed. Phylogenetic analyses based on the ORF2 amino acid sequences, samples described herein grouped into the putative genotype 'a' closed related with Chinese samples. Other studies are required to attempt the clinical and antigenic implications of these astrovirus genotypes in dogs.

Keywords: Canine astrovirus; Dog; Gastroenteritis; MAstV5; Mamastrovirus 5.

Fig. 1

Presumptive association between the MAstV5-positive samples (multiple or single infection) and the presence of clinical signs in the sampled dogs.

Fig. 2

Evolutionary relationship of MAstV5 with representative MAstV genera. The percentage of replicates in which the associated virus clustered together in the bootstrap test (1000 replicates) is shown next to the branches in each tree. The trees are drawn to scale; bars represent the number of substitutions per site. All positions except ambiguous positions were included. Bootstrap values <50 were excluded. GenBank accession numbers are shown on the tree. MAstV5 sequences obtained in the present study are indicated with a black dot (●). The Kimura 2-parameter substitution model was selected for the MAstV5 ORF2 nucleotide inference, and the LG substitution model (frequencies +F) was used for the amino acid inference. The substitution-rate variation among sites was modeled with a gamma distribution (shape parameter = 5). (A) Evolutionary tree based on the complete amino acid sequences of the ORF2 gene (capsid) of 47 nucleotide sequences of AstVs. (B) Evolutionary tree based on the partial nucleotide sequences of ORF2 from 30 sequences of MAstV5.

Fig. 2

Evolutionary relationship of MAstV5 with representative MAstV genera. The percentage of replicates in which the associated virus clustered together in the bootstrap test (1000 replicates) is shown next to the branches in each tree. The trees are drawn to scale; bars represent the number of substitutions per site. All positions except ambiguous positions were included. Bootstrap values <50 were excluded. GenBank accession numbers are shown on the tree. MAstV5 sequences obtained in the present study are indicated with a black dot (●). The Kimura 2-parameter substitution model was selected for the MAstV5 ORF2 nucleotide inference, and the LG substitution model (frequencies +F) was used for the amino acid inference. The substitution-rate variation among sites was modeled with a gamma distribution (shape parameter = 5). (A) Evolutionary tree based on the complete amino acid sequences of the ORF2 gene (capsid) of 47 nucleotide sequences of AstVs. (B) Evolutionary tree based on the partial nucleotide sequences of ORF2 from 30 sequences of MAstV5.