Identification and complete genome sequences of two novel double-stranded RNA viruses infecting the basal fungus Conidiobolus lii

Abstract

Here, we present the identification and complete genome sequences of two novel double-stranded RNA (dsRNA) viruses coinfecting the basal fungus Conidiobolus lii isolate RCEF7535. The viruses, named Conidiobolus lii ootivirus 1 (ClOV1) and Conidiobolus lii totivirus 1 (ClTV1), exhibit distinct genomic characteristics. The genome of ClOV1 is 5,909 nucleotides in length and contains two open reading frames (ORFs). ORF1 encodes a 724-amino-acid capsid protein (CP) with a molecular weight of 80.80 kDa that shows 25.11% sequence identity to the CP of Conidiobolus lamprauges totivirus 1. ORF2 encodes a 743-amino-acid RNA-dependent RNA polymerase (RdRp) with a molecular weight of 83.22 kDa that shares 42.03% sequence identity with the RdRp of Conidiobolus chlamydosporus totivirus 2. The genome of ClTV1 is 4,653 nucleotides in length and contains two ORFs, with ORF1 encoding a 690-amino-acid hypothetical protein (HP, 78.18 kDa) and ORF2 encoding a 799-amino-acid RdRp (90.95 kDa). Both ORFs of ClTV1 display high sequence similarity to hypothetical proteins of Wuhan insect virus 27, with 70.25% identity in the HP and 68.76% identity in the RdRp. Phylogenetic analysis based on RdRp sequences showed that ClOV1 grouped with viruses of the genus Ootivirus within the family Ootiviridae, while ClTV1 clustered with viruses of the genus Totivirus of the family Orthototiviridae. This discovery enhances our understanding of mycovirus diversity, particularly in basal fungi, by identifying novel viruses infecting members of the genus Conidiobolus.