ANTIGENICITY AND IMMUNOGENICITY OF RECOMBINANT ENVELOPE GLYCOPROTEINSOF SIVMAC32H WITH DIFFERENT IN-VIVO PASSAGE HISTORIES

Shortly after infection of two rhesus monkeys (Macaca mulatta) SIVmac3 2H challenge stock or with the same virus that had been passaged in an other rhesus monkey for II months, SIV-envelope genes were cloned fr o m their peripheral blood mononuclear cells and subsequently expressed by recombinant vaccinia viruses. The molecular weights and antigenicit ies of the thus produced envelope glycoproteins were largely identical to those of the native SIV. The envelope glycoprotein derived from th e in vivo passaged virus proved to be poorly recognized by virus neutr alizing monoclonal antibodies directed against one of the seven antige nic sites for which monoclonal antibodies were available. Immunization studies in rats showed that this protein was also less efficient in i nducing antibodies against this antigenic site, and that it induced si gnificantly lower levels of virus neutralizing antibodies than the oth er SIV-envelope glycoprotein. The immunogenicity of the SIV-envelope g lycoprotein incorporated into immune stimulating complexes (iscoms) wa s compared to that of the same protein presented with Quil A or MDP-ts l.