Structure of the Triatoma virus capsid.

Joan Pous,Stéphane Bressanelli,Gerardo A. Marti,Gaëlle Squires,Diego M. A. Guérin,Jorge Navaza,Felix A. Rey,Jon Agirre,Gabriela S. Rozas-Dennis,Marcelo D. Costabel

doi:10.1107/s0907444913004617

Abstract

The members of the Dicistroviridae family are non-enveloped positive-sense single-stranded RNA (+ssRNA) viruses pathogenic to beneficial arthropods as well as insect pests of medical importance. Triatoma virus (TrV), a member of this family, infects several species of triatomine insects (popularly named kissing bugs), which are vectors for human trypanosomiasis, more commonly known as Chagas disease. The potential use of dicistroviruses as biological control agents has drawn considerable attention in the past decade, and several viruses of this family have been identified, with their targets covering honey bees, aphids and field crickets, among others. Here, the crystal structure of the TrV capsid at 2.5 Å resolution is reported, showing that as expected it is very similar to that of Cricket paralysis virus (CrPV). Nevertheless, a number of distinguishing structural features support the introduction of a new genus (Triatovirus; type species TrV) under the Dicistroviridae family. The most striking differences are the absence of icosahedrally ordered VP4 within the infectious particle and the presence of prominent projections that surround the fivefold axis. Furthermore, the structure identifies a second putative autoproteolytic DDF motif in protein VP3, in addition to the conserved one in VP1 which is believed to be responsible for VP0 cleavage during capsid maturation. The potential meaning of these new findings is discussed.

Highlights

Triatoma virus (TrV) is a pathogen of Triatoma infestans and other related bloodsucking insects that are vectors of Chagas disease
In an effort to identify entomopathogens as biological weapons against the vector, TrV was isolated from T. infestans (Muscio et al, 1987), the main species transmitting Chagas disease in the southern countries of Latin America (Zeledon & Rabinovich, 1981)
We provide a detailed analysis of the structure in comparison to that of the Cricket paralysis virus (CrPV) capsid, showing that TrV differs substantially in surface features, in the absence of an ordered VP4 molecule in the capsid interior and in the presence in VP3 of a structurally conserved catalytic motif involving the same DDF sequence as in VP1

Summary

Introduction

Triatoma virus (TrV) is a pathogen of Triatoma infestans and other related bloodsucking insects ( called ‘kissing bugs’) that are vectors of Chagas disease. This disease is a major health problem in Latin America, where it is endemic and affects about eight million people, 30–40% of whom develop cardiomyopathy and/or digestive megasyndromes (Rassi et al, 2010). Increasing human population movements have resulted in Chagas disease becoming an emerging health problem outside the countries in which it is endemic. In an effort to identify entomopathogens as biological weapons against the vector, TrV was isolated from T. infestans (Muscio et al, 1987), the main species transmitting Chagas disease in the southern countries of Latin America (Zeledon & Rabinovich, 1981)

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Conclusion