The Broad Host Range and Genetic Diversity of Mammalian and Avian Astroviruses

Abstract

Astroviruses are a diverse family of viruses that infect a wide range of mammalian and avian hosts. Here we describe the phylogenetic diversity and current classification methodology of astroviruses based on the ORF1b and ORF2 genes, highlighting the propensity of astroviruses to undergo interspecies transmission and genetic recombination which greatly increase diversity and complicate attempts at a unified and comprehensive classification strategy.

Keywords: ORF1b; ORF2; RNA-dependent-RNA-polymerase; astrovirus; avian; capsid; classification; genetic diversity; mammal.

Figure 1

Maximum-likelihood phylogenetic tree of Mamastrovirus (MAstV) capsid (a) and RNA-dependent RNA polymerase (RdRp) (b) genes. Trees were generated from nucleotide sequences using the maximum-likelihood method with the general time reversible nucleotide substitution model with gamma distribution (GTRG+G) and 1000 bootstrap replicates and nodes with bootstrap support values ≥70 are shown by an asterisk. Proposed species yet to be recognized are designated with a ^ symbol. Strains are colored by host and trees with full taxa names are provided as Supplementary Materials (Figures S1 and S2).

Figure 2

Maximum-likelihood phylogenetic tree of Avastrovirus (AAstV) (a) capsid and (b) RdRp genes. Trees were generated from nucleotide sequences using the maximum-likelihood method with the GRT+G nucleotide substitution model and 1000 bootstrap replicates and nodes with bootstrap support values ≥70 are shown by an asterisk. Proposed species yet to be recognized are designated with a ^ symbol. Strains are colored by host and trees with full taxa names are provided as Supplementary Materials (Figures S3 and S4).