Identification and molecular characterization of a new double-stranded RNA virus infecting Chondrostereum purpureum

Document Type

Article

Publication Date

12-1-2008

Abstract

A new double-stranded RNA (dsRNA) virus, designated Chondrostereum purpureum cryptic virus (CPCV), belonging to the family Partitiviridae, has been identified in the basidiomycete fungus Chondrostereum purpureum. The virus does not appear to be distributed widely and was detected in only one (PFC2064) of 20 C. purpureum isolates screened. Visualization by electron microscopy revealed isometric virus particles, approximately 30 nm in diameter. Analysis of purified dsRNA revealed two distinct bands that were cloned and sequenced. Double-stranded RNA1 was 1920 base pairs (bp) in size, and dsRNA2 was 1757 bp, excluding the poly(A) tails at the 3' terminus of each fragment. Each RNA contains a single open reading frame (ORF) with short 5' and 3' untranslated regions, 44 and 115 nucleotides (nt) and 90 and 227 nt, respectively. The deduced 587 amino acid (aa) protein (Mr = 68.1 kDa) encoded by the dsRNA1 ORF showed homology to the RNA-dependent RNA polymerase (RdRp) of viruses belonging to the family Partitiviridae. Eight motifs associated with RdRp were identified, including the highly conserved glycine - aspartic acid - aspartic acid sequence. The dsRNA2 ORF encodes the putative coat protein subunit (480 aa, Mr = 52.8 kDa). Basic local alignment search tool analysis of the nucleotide sequence of dsRNA2 revealed no matches in GenBank; however, low identity (16%-24%) was observed for the CPCV coat protein amino acid sequence compared with members of the family Partitiviridae. The dsRNA profile, amino acid sequence alignments, and phylogenetic analyses all indicate that CPCV is most closely related to members of the genus Alphacryptovirus within the family Partitiviridae.

Publication Source (Journal or Book title)

Canadian Journal of Plant Pathology

First Page

604

Last Page

613

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