Complete genome sequence of a novel alternavirus infecting Fusarium falciforme

We present the complete genome sequence of a novel alternavirus, tentatively named "Fusarium falciforme alternavirus 1 (FfAV1)", isolated from Fusarium falciforme. The host, F. falciforme strain Fod375, was isolated from a soil sample in Spain in 2012 and was found to be infected with a virus containing a tetra-segmented double-stranded (ds) RNA genome. The genome segments, designated as dsRNA1 (3529 bp), dsRNA2 (2641 bp), dsRNA3 (2459 bp), and dsRNA4 (1471 bp), each possess a single open reading frame (ORF). The protein predicted from dsRNA1 contains the typical domains of an RNA-dependent RNA polymerase (RdRP) homologous to those of previously reported alternaviruses, while the protein predicted from dsRNA3 shows homology to alternavirus capsid proteins. The proteins encoded by dsRNA2 and dsRNA4 are of unknown function. All predicted proteins exhibited the highest sequence identity with their counterparts in Hebei alternavirus and Marquandomyces marquandii alternavirus 1. Phylogenetic analysis supported the placement of this FfAV1 isolate within the genus Alternavirus. Considering these results, we propose that FfAV1, along with the two closely related unassigned alternaviruses, represents a new species within the genus.