Molecular characterization of a novel alternavirus infecting the entomopathogenic fungus Cordyceps chanhua

Abstract

In this study, a novel double-stranded (ds) RNA mycovirus, named Cordyceps chanhua alternavirus 1 (CcAV1), was detected in the entomogenous fungus Cordyceps chanhua in China and characterized. The complete genome of CcAV1 is composed of three dsRNA segments: dsRNA 1 (3,512 bp), dsRNA 2 (2,655 bp), and dsRNA 3 (2,415 bp). Each of the three dsRNAs possesses a single open reading frame (ORF). dsRNA 1 encodes a putative RNA-dependent RNA polymerase (RdRp), and dsRNA 2 and dsRNA 3 encode hypothetical protein 1 (HP 1) and hypothetical protein 2 (HP 2), respectively. The predicted amino acid sequences of the putative RdRp, HP 1, and HP 2 had the highest identity of 66.99%, 49.30%, and 56.91%, respectively, to those of Aspergillus foetidus dsRNA mycovirus. A maximum-likelihood phylogenetic tree based on RdRp amino acid sequences showed that CcAV1 clustered with members of the proposed family "Alternaviridae". Hence, we propose that Cordyceps chanhua alternavirus 1 is a novel member of the proposed family "Alternaviridae".