Interactions between pepper ringspot virus and cylindrical inclusions of two potyviruses

Immunoelectron microscopy showed that cylindrical inclusions (CI) of the potyvirus potato virus Y (PVY) bound in addition to their homologous virions those of a co-infecting rod-shaped virus, pepper ringspot virus (PRV), in infected Nicotiana benthamiana leaf cells. The latter virus does not code for cylindrical inclusions and is cl assified as a Tobravirus. Virions of PRV were scattered throughout the cell cytoplasm and not associated with mitochondria in PVY + PRV double infections. Binding of PRV to mitochondria was disrupted in PVY + PRV infected cells. In double infections with a second potyvirus, tobacco etch virus (TEV), and PRV in N. benthamiana cells, TEV-CI bound homologous TEV virions but did not bind PRV. In contrast to PVY + PRV infections, virions of PRV attached end-on to mitochondrial limiting membranes in PRV-only and in TEV + PRV double infections. The results are interpreted to mean that there are differences in the PRV virion binding sites of PVY-CI and TEV-CI. In previous reports, potyviral CI have been nondiscriminating in binding virions or capsid proteins of other co-infecting rod-shaped viruses.