ROLES AND REACTIVITIES OF ANTIBODIES TO ALPHAVIRUSES

Antibodies to alphaviruses are essential for recovery from infection. These antibodies act by interacting with the E1 and E2 glycoproteins on the virion and on the surface of infected cells. E1 epitopes are displayed primarily on infected cells and are cryptic on the virion until after exposure to acidic pH. A single neutralizing epitope (E1-c) includes E1 residue 132. Two dominant neutralizing domains have been identified on the Sindbis virus E2: E2-ab from E2-190 to 214 and E2-c from E2-62 to 159. E2-ab is likely to form a single loop and contain linear determinants while E2-c is strictly conformational involving several sites on the linear molecule. Both neutralizing and non-neutralizing E1 and E2 MAbs can protect and promote recovery from fatal encephalitis. E2 MAb can clear infectious virus from persistently infected cells by a non-cytolytic process and acts synergistically with interferon.