Viral movemement protein which is responsible for cell-to cell spread of viral genome. Increases the size exclusion limit (SEL) of plasmodesmata by forming tubules structures, thereby allowing viral ribonucleocapsids to spread directly to neighboring cells (By similarity). Oligomerizes to form tubule structures through host plasmodesma. Interacts with host A.thaliana At4g26020 protein, which is involved in antra- and inter-cellular trafficking (By similarity). Colocalizes with viral nucleocapsid aggregates in host cytoplasm. Belongs to the tospovirus movement protein family.