Molecular characteristics of a novel alternavirus from Trichoderma harzianum

We analyzed the dsRNA profiles of Trichoderma spp. and identified a novel mycovirus from Trichoderma harzianum strain NFCF419. This virus belongs to a member of the family Alternaviridae . NGS analysis revealed that this virus consisted of four genome segments. The complete genome sequences of the segments were determined by NGS, in combination with manual sequencing of RT-PCR amplicons using specific primer pairs, and 5'- and 3'-RACE. Its genome consists of four segments of 3,572 bp (dsRNA1), 2,552 bp (dsRNA2), 2,593 bp (dsRNA3), and 1,484 bp (dsRNA4). The largest segment (dsRNA1) contains a single open reading frame (ORF) encoding a putative RNA-dependent RNA polymerase (RdRP). Each of dsRNA2, 3, and 4 comprises a single ORF encoding a putative methyltransferase, a coat protein, and a hypothetical protein with unknown function, respectively. Evaluation of the genome organization, deduced amino acid sequences of RdRP, and phylogenetic analysis indicated that this virus is a new member of the genus Alternavirus in the family Alternaviridae . Accordingly, we designated this novel mycovirus Trichoderma harzianum alternavirus 1 (ThAV1). This is the first report of a mycovirus in the family of Alternaviridae that infects the genus Trichoderma .