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

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.

Direct methods for detecting picorna-like virus from dead and alive Triatomine insects

In this work we report four different destructive and non-destructive methods for detecting picorna-like virus particles in triatomines. The methods are based on direct observation under transmission electron microscope and they consist of four ways to prepare samples of presumable infected material. The samples are prepared processing dead or alive insect parts, or even dry or fresh insect feces. The methods can be used as analytical or preparative techniques, for quantifying virus infection and checking virus integrity as well. In this work the four methods are applied in order to detect Triatoma virus (TrV) particles in T. infestans colonies.

Triatoma virus pathogenicity in laboratory colonies of Triatoma infestans (Hemiptera:Reduviidae).

In a survey of wild populations of Triatoma infestans (Klug) in Argentina, 10% were infected with Triatoma virus (TrV). The virus also was detected in a laboratory colony 18 mo after being established, with infection rates up to 100%. Mortality rate was 97.6% in nymphs and the molting process was inhibited, thereby increasing development time. Because the virus was detected in colony nymphs. TrV may be transmitted vertically. However, the higher infection rate in the colony compared with natural populations also indicates other route(s) of transmission.

Characterization of Triatoma virus, a picorna-like virus isolated from the triatomine bug Triatoma infestans.

Some properties of Triatoma virus (TrV), a picorna-like virus recently isolated from Triatoma infestans, have been studied. Electron microscopic observations of purified viral preparations showed the presence of non-enveloped viral particles 30 nm in diameter. The sedimentation coefficient of virus particles was about 165S and the buoyant density in CsCl was 1.39 g/ml. The viral genome was composed of one single-stranded RNA molecule with an Mr of 3 x 10(6). Three major polypeptides with Mr values of 39K, 37K and 33K and a minor one of about 45K were found in the virus particle. TrV particles contain about 35% RNA and 65% protein by weight. These data support the classification of this virus in the family Picornaviridae.