Complete genome sequence of the first alphahypovirus from the phytopathogenic fungus Curvularia americana on Poa pratensis in China.

In the present study, a novel positive-sense single-stranded RNA virus was identified from Curvularia americana strain 32 - 2, a phytopathogenic fungus infecting Poa pratensis in China, which was designated as "Curvularia americana hypovirus 1" (CaHV1). The complete genome of CaHV1 consists of 14,386 nucleotides (nt) with a single large open reading frame (ORF) (nt position 593 to 14035). The ORF encodes a putative polyprotein (4,480 amino acids) containing two potential conserved domains, which includes a Domain of Unknown Function 3525 (DUF3525) and Helicase. BLASTp analysis showed that amino acid sequence of the polyprotein of CaHV1 shared the highest amino acid sequence identity with that of Bipolaris oryzae hypovirus 1 (63.52%). Phylogenetic analysis based on amino acid sequence of the polyprotein indicated that CaHV1 clustered together with members of the genus Alphahypovirus within the family Hypoviridae. To the best of our knowledge, this is the first report of an alphahypovirus infecting C. americana.