New viruses of Cladosporium sp. expand considerably the taxonomic structure of Gammapartitivirus genus

Abstract

Despite the fact that Cladosporium sp. are ubiquitous fungi, their viromes have been little studied. By analysing a collection of Cladosporium fungi, two new partitiviruses named Cladosporium cladosporioides partitivirus 1 (CcPV1) and Cladosporium cladosporioides partitivirus 2 (CcPV2) co-infecting a strain of Cladosporium cladosporioides were identified. Their complete genome consists in two monocistronic dsRNA segments (RNA1 and RNA2) with a high percentage of pairwise identity on 5’ and 3’ end. The RNA dependant RNA polymerase (RdRp) of both viruses and the capsid protein (CP) of CcPV1 display the classic characteristics required for their assignment to the Gammapartitivirus genus. In contrast, CcPV2 RNA2 encodes for a 41 KDa CP that is unusually small with a low percentage of amino acid identity as compared to CPs of other viruses classified in this genus. This sequence was used to annotate fifteen similar viral sequences with unconfirmed function. The phylogeny of the CP was highly consistent with the phylogeny of their corresponding RdRp, supporting the organization of gammapartitiviruses into three distinct clades despite stretching the current demarcation criteria.