Expression of the movement protein of tomato spotted wilt virus in the insect vector Frankliniella occidentalis.

Tomato spotted wilt virus (TSWV) is able to infect both its botanical hosts and its insect vector (thrips). In plant tissue the NSM protein of TSWV functions as viral movement protein (MP), aggregating into plasmodesma-penetrating tubules to establish cell-to-cell movement. As upon heterologous expression NSM was able to form similar tubules on the surface of insect (Spodoptera frugiperda) cells, we have now investigated the expression and cellular manifestation of this protein in infected thrips tissue. It is shown that NSM, though detectably expressed in both the L2 larval and adult thrips stages, does not aggregate into tubules, indicating that this requirement is associated to its function as MP in plants, and raising the question if NSM has a function at all during the insect life cycle of TSWV