 Electron microscopy showing viral particles confirmed the role of a virus.On infection of a susceptible nematode, the viral particles are mainly localized to intestinal cells.The small structure of the Orsay virus, its resemblance to the well-studied nodaviruses and its tropism to intestinal cells of "C. elegans", together with its lack of infectivity for humans, make the Orsay virus a useful virus for studying host–virus interactions.