Nucleotide sequence analysis of Triatoma virus shows that it is a member of a novel group of insect RNA viruses

Abstract

Triatoma virus (TrV) is the only virus described to date that infects triatomines, and has previously been considered to be a member of the family Picornaviridae on the basis of physico-chemical properties. The genome of TrV was sequenced completely (9010 nt). Analysis of the sequence revealed the presence of two large open reading frames (ORFs). The predicted amino acid sequence of ORF1 (nt 549-5936) showed significant similarity to the non-structural proteins of several animal and plant RNA viruses. This ORF product contains sequence motifs characteristic of RNA-dependent RNA polymerases (RdRp), cysteine proteases and RNA helicases. ORF1 is preceded by 548 nucleotides of non-coding RNA and the two ORFs are separated by 172 nucleotides of non-coding RNA. Direct N terminus sequence analysis of two capsid proteins showed that ORF2 (nt 6109-8715) encodes the structural proteins of TrV. The predicted amino acid sequence of ORF2 is very similar to the corresponding regions of Drosophila C virus, Plautia stali intestine virus, Rhopalosiphum padi virus and Himetobi P virus and to a partial sequence from the 3' end of the cricket paralysis virus genome. All of these viruses have a novel genome organization and it has been proposed that they are not members of the Picornaviridae, as previously thought, but belong to a new virus family. On the basis of similarities of genome organization, we propose that TrV also belongs to this new virus family.