Afrina barna-like Virus, a Novel Virus Associated with Afrina sporoboliae, the Drop Seed Gall-Forming Nematode

A novel barna-like virus was found to be associated with field-collected Afrina sporoboliae plant-parasitic nematodes. The positive-sense, single-stranded RNA genome of this virus, named Afrina barna-like virus (AfBLV), comprises 4020 nucleotides encoding four open reading frames (ORFs). ORF 1 encodes a protein product spanning a transmembrane, a peptidase, and VPg domains, whereas an overlapping ORF 2 encodes an RNA-dependent RNA polymerase (RdRP). ORF2 may be expressed via a −1 translational frameshift. In phylogenetic reconstructions, the RdRP of AfBLV was placed inside a separate clade of barna and barna-like viruses related to but distinct from the genera in the Solemoviridae and Alvernaviridae families, within the overall lineage of Sobelivirales. ORF 3 of AfBLV encodes a protein product of 206 amino acids (aa) long with homology to a putative protein encoded by a similarly positioned gene of an uncharacterized virus sequence identified previously as Barnaviridae sp. ORF 4 encodes a 161 aa protein with no significant similarities to sequences in the GenBank databases. AfBLV is the first barnavirus found in a nematode. Sequence comparisons of the AfBLV genome and genomes of other barna-like viruses suggested that a recombination event was involved in the evolution of AfBLV. Analyses of the phylogeny of RdRPs and genome organizations of barna-like and solemo-like viruses support the re-classification of Barnavirus and Dinornavirus genera as members of the Solemoviridae family.