CryoEM structures of icosahedral RNA plant viruses from the family Secoviridae

Póster presentado en el XX Congreso de la Sociedad Española de Fitopatología celebrado en Valencia del 24 al 26 de octubre de 2022.

The family Secoviridae contains viruses with positive-sense ssRNA genomes, bipartite or monopartite, and non-enveloped icosahedral or spherical virions. The family includes eight genera with different modes of transmission (non-persistent or semipersistent) by insects or nematodes vectors. Viral-encoded proteins have been identified to specifically interact with their respective vectors and facilitate virus transmission. One of the methodologies that has been used to deepen our understanding on plant virus transmission mechanisms is the use of cryoelectron microscopy (CryoEM). By solving the virion structure of plant viruses, we can know in close detail which are the motifs exposed to the outer surface of the virions that could be interacting with their vector’s mouthparts. The CryoEM structures of some members of the family Secoviridae such as comoviruses, nepoviruses and cheraviruses have been solved previously. However, there still a lack of knowledge on the structure of other members of the family Secoviridae such as torradoviruses and also within members of the subfamily Comovirinae, such as the fabaviruses. In this work, we aimed to solve the virion structures of the aphid-transmitted broad bean wilt virus 1 (BBWV-1, genus Fabavirus; subfamily Comovirinae), and of the whitefly-transmitted torradovirus tomato apex necrosis virus (ToANV, genus Torradovirus). High-resolution structures were obtained after the purification of BBWV-1 virions or ToANV VLPs produced using the pEAQ expression system. Our results showed close relations of these structures with other members of the family Secoviridae and also with other insect viruses.