Molecular characterization of a novel partitivirus harboring an additional third dsRNA segment from Trichoderma harzianum

We report the complete genome sequence of a novel partitivirus identified from Trichoderma harzianum NFCF092 strain, designated Trichoderma harzianum partitivirus 4 (ThPV4). Unlike canonical members of the family Partitiviridae, which possess a bipartite genome consisting of two double-stranded RNA (dsRNA) segments encoding an RNA-dependent RNA polymerase (RdRP) and a capsid protein (CP), ThPV4 harbors a third dsRNA segment encoding a protein of unknown function. The complete genome consists of dsRNA1 (1,950 bp; encoding the RdRP), dsRNA2 (1,772 bp; encoding the CP), and dsRNA3 (1,629 bp; encoding a protein with unknown function). Sequence analysis shows that each segment possesses a single open reading frame (ORF). The deduced amino acid sequence of the RdRP shows the highest similarity (90.5% identity) to that of Trichoderma gamsii alphapartitivirus 1. Phylogenetic analyses based on the RdRP indicate that ThPV4 clusters within the genus Alphapartitivirus of the family Partitiviridae. To our knowledge. ThPV4 is the first member of the genus Alphapartitivirus identified from T. harzianum to possess an additional, conserved third dsRNA segment.