Properties of monoclonal antibodies directed against the glycoproteins of Sindbis virus.

Four monoclonal antibodies that react with Sindbis virus glycoproteins have been examined for (i) their effects on virus infectivity, (ii) their ability to recognize conformational changes in glycoprotein structure, and (iii) their cross-reaction with several different alphaviruses. Two of the monoclonal antibodies reacted with the native forms of the E1 glycoprotein but did not neutralize virus infectivity. One of the anti-E1 antibodies formed an infectious virus-antibody complex. The other two monoclonal antibodies reacted with the E2 glycoprotein in both an unfolded as well as a native structure. One of these antibodies reacted with Semliki Forest virus. The anti-E1, but not the anti-E2, antibodies cross-reacted with three serologically related equine encephalomyelitis viruses.