Cryo-EM reconstructions of Triatoma Virus empty capsids indicate that this virus doesn?t match picornavirus RNA delivery models

EMMANUELLE NEUMANN; AGIRRE, J; GAËL GORET; LEGOFF, M; SANCHEZ- EUGENIA, R; MARTI G. A; NAVAZA J; GUERIN, D.M.A.

Simposio; Seventh International Virus Assembly Symposium; 2012

Triatoma Virus (TrV) is a member of the insect virus family Dicistroviridae and consists of a small, non-enveloped capsid (T=1, p=3) that encloses a +ssRNA genome. Using cryo-electron microscopy, and 3D reconstruction techniques combined with the crystallographic atomic model, we present three reconstructions of the TrV capsid in different states: full particles (protein shell containing the genome); naturally occurring empty particles (protein shell without RNA); and  experimentally obtained empty particles (protein shell resulting after release of the RNA by heating full particles). These reconstructions, along with other biophysical results, show that upon genome release, no striking structural changes are observed on the empty capsid proteins to respect their initial position in full particles. Our results support in TrV a genome delivery mechanism that differs from the processes described for picornaviruses Human Rhino Virus 2 and Polio Virus.