Enhanced immunogenicity of a human immunodeficiency virus type 1 env DNA vaccine by manipulating N-glycosylation signals - Effects of elimination of the V3N306 glycan

DNA encoding HIV-1 env is a poorly efficient B-cell immunogen and one proba ble explanation is that the numerous gp 120 N-linked glycans gp120 may inte rfere with B-cell epitope presentation. The N306 glycan in gp120 shields HI V-1 from neutralizing antibodies. A DNA immunogen lacking the N306 glycosyl ation signal (T308A) was constructed to determine whether this glycan affec ted the immune response. Mice were immunized intranasally twice with DNA co ntaining either the wild type or the mutant env, Two additional groups were primed with wild type or mutant env and boosted with rgp 160 protein, cont aining the complete set of N-linked glycans. Immunization with DNA alone re sulted in priming of B-cell clones but was not sufficient to induce a compl ete antibody response. Animals primed with the N306 mutant and subsequently boosted with rgp 160 protein displayed higher serum IgG-binding titers to gp 120 than animals primed with wild type env DNA. The manipulation of the glycosylation sites of the env DNA strongly primes antibody responses (but non-neutralizing) as well as T-cell responses to the wild type strain ap 16 0. However, priming with mutant plasmid did not result in higher neutraliza tion titers to wild type or T308A-mutated virus than did the wild type plas mid. With the N306 mutant DNA we thus immunized a non-neutralization epitop e, but obtained strong env-binding IgG after rgp160 boosting. (C) 2001 Else vier Science Ltd. All rights reserved.