The crystallographic structure of Triatoma Virus provides new insights into the Dicistroviridae family

AGUIRRE, J; SQUIRES, G; POUS, J; ROZAS-DENNNIS, G; COSTABEL, M.D; MARTI, G. A,; BRESSANELLI, S; NAVAZA J; GUERIN, D.M.A.; REY, F, A

Simposio; Seventh International Virus Assembly Symposium; 2012

Triatoma virus (TrV) is an insect virus that belongs to the Dicistroviridae family and infects several species of triatomine insects, which are popularly named kissing bugs, the vectors for human trypanosomiasis, commonly known as Chagas disease. Dicistroviruses are non-enveloped +ssRNA viruses pathogenic to both beneficial arthropods and insect pests of medical importance, and therefore have drawn considerable attention in the past decade due to their potential use as biological control agents. In the present work we report the crystallographic structure of the TrV capsid at 2.5 Å resolution. The structure reveals a number of distinctive features with respect to the capsid of the Cricket Paralysis Virus (CrPV), the only structure available of a virus from this family. These differences are enough to propose the introduction of a new genus (Triatovirus; type-species: TrV) within the Dicistroviridae family. Indeed, TrV has a more expanded capsid built with fewer residues, presenting crown-like spikes around the 5-fold axes, which are absent in CrPV. Two metal ions and a string of uninterpreted density block the channels present along the 5-fold axes of the TrV particle. Furthermore, it displays two autoproteolytic motifs necessary for particle maturation at the capsid interior, instead of one in CrPV. Finally, and most importantly, the structure shows the absence of an ordered VP4 protein within mature, infectious TrV particles. These difference in the capsid likely reflect the different hosts in which TrV replicates.