Antibody-induced capping of measles virus antigens on plasma membrane studied by electron microscopy.

Antibodies specific for measles virus could redistribute ("cap") virus antigens on infected HeLa cells as shown by transmission and scanning electron microscopy. Using an indirect immunoperoxidase technique, infected cells showed diffuse, circumferential distribution of virus antigens over the cell surface when mixed with antibody at 4 C. At 37 C, virus-coated microvilli concentrated on one pole of the cell, leaving the remainder of the plasma membrane devoid of both viral antigens and microvillus projections. Whereas extreme polar displacement of virus-antibody complexes frequently occurred, endocytosis was rarely seen. The findings indicate that antiviral antibodies can move and cluster virus on plasma membranes and suggest that virus-antibody complexes are stripped and shed from the cell surface.