The Fab portion
of IgG binds to epitopes of the viral surface. The Fc portion can now attach
the virus to Fc receptors on phagocytes for enhanced attachment. Once
attached to the phagocyte by way of IgG, the virus can be engulfed more efficiently,
placed in a phagosome, and destroyed by lysosomes. C3b and C4b from the activated
complement pathways are also able to attach viruses to phagocytes.