SH2D3C and infection: Previous live-cell microscopy revealed three subclasses of nsP3 structures during SFV infection: (i) small, nonacidic, nsP3-positive vesicles undergoing multidirectional and short-distance (2-μm) movement reminiscent of actin-based movement, (ii) large, acidic vesicles displaying less-frequent jumps over distances of >10 μm, and (iii) large, acidic vesicles that were immobile and concentrated in the perinuclear area (51).