7th International AIDS Conference Florence, Italy — June 16-21, 1991

Int Conf AIDS 1991 Jun 16-21; 7:38 (abstract no. M.A.63)
Benjouad A, Gluckman JC, Rochat H, Montagnier L, Bahraoui E; CERVI Pitie-Salpetriere Medical School, Paris, France

OBJECTIVE: To investigate the specificity and neutralizing capacity of antibodies raised against native, or partially or totally deglycosylated rgp160 of HIV-1 Bru.

METHODS: Rabbits were immunized with rgp160 or deglycosylated derivatives obtained by either neuraminidase, or mannosidase or Endo F-N glycanase. Specificity of antibodies thus elicited, were analysed by RIA against HIV-1 or HIV-2 radiolabeled envelope glycoproteins, and by ELISA against a panel of synthetic peptides. Anti-sera were further characterised for their ability to block HIV-1 binding to CD4-positive cells and to inhibit syncytium formation.

RESULTS: Immunized rabbits produced antibodies that recognized rgp160 from HIV-1 in RIA or ELISA. Analysis of the reactivity of antibodies raised after carbohydrate removal against a panel of synthetic peptides indicated that serum reactivity to some peptides improved while the reactivity to others decreased or remained unchanged. For example, only antibodies raised against mannosidase-treated rgp160 failed to react with the V3 loop synthetic peptide of gp120. Rabbits immunized with desialylated rgp160 generated antibodies able to recognize, with high titers, not only rgp160 from HIV-1 but also rgp140 from HIV-2. Although all antisera produced against glycosylated or deglycosylated rgp160 were able to block HIV-1 binding to CD4-positive cells in vitro, only antibodies raised against desialylated rgp160 totally inhibited syncytium formation between HIV-1 infected cells and non-infected CD4-positive cells.

CONCLUSIONS: These results indicate that carbohydrate moieties of HIV-1 rgp160 can modulate the specificity of the immune response as demonstrated by the large cross reactivity of desialylated rgp160 and by the variation of the reactivity to V3 loop of antibodies raised against different forms of deglycosylated rgp160. Such information can be used to develop an efficient vaccine against HIV.

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