Molecular characterization of a novel fusarivirus infecting the edible fungus Auricularia heimuer.

Here, we describe a novel mycovirus, Auricularia heimuer fusarivirus 1 (AhFV1), isolated from the edible fungus Auricularia heimuer strain CCMJ1296. The virus has a single-stranded positive-sense [+ssRNA] genome of 7,127 nucleotides containing two overlapping open reading frames (ORFs) and a poly(A) tail. The large ORF1 encodes a polyprotein of 1,637 amino acids (aa) with conserved RNA-dependent RNA polymerase (RdRp) and DEAD-like helicase superfamily (DEXDc) domains. ORF2 encodes a putative 633-aa protein with unknown function. A BLAST search showed that the nucleotide sequence of the AhFV1 genome is 41.28% identical to that of Sclerotium rolfsii fusarivirus 2 and 40.49% identical to that of Sclerotium rolfsii fusarivirus 1. Phylogenetic analysis based on RdRp and helicase (Hel) sequences indicated that AhFV1 is related to unclassified mycoviruses and other fusariviruses. Our data suggest that AhFV1 should be classified as a member of the newly proposed family "Fusariviridae". This is the second virus and the first full genome sequence of a fusarivirus from A. heimuer.

Molecular characteristics of a novel ssRNA virus isolated from Auricularia heimuer in China.

A novel positive-sense single-stranded RNA virus was isolated from strain CCMJ1271 of the fungus Auricularia heimuer, and the complete genome sequence of the virus was determined. Database searching, sequence alignment, and phylogenetic analysis revealed that this fungal virus and some viruses of family Virgaviridae clustered into a single branch of a phylogenetic tree, and we thus tentatively named the virus "Auricularia heimuer mycovirgavirus 1" (AhMV1). The AhMV1 genome consists of 9,934 nucleotides and contains a short poly(A) tail and three open reading frames (ORFs). ORF1 encodes an RNA-dependent RNA polymerase (RdRp), ORF2 encodes a protein that is homologous to movement proteins of plant virgaviruses, and ORF3 encodes a coat protein (CP). AhMV1 is the first virus to be discovered in A. heimuer.