12th International AIDS Conference Geneva, Switzerland - June 28-July 3, 1998

Int Conf AIDS 1998 Jun 28-Jul 3; 12:23 (abstract no. 11206)

May J, Berry NJ, Ariyoshi K, Whittle H, Mttchell M, Balfe P, Loomis-Price L
Department of Virology, UCLMS, London, UK.

BACKGROUND: Epidemiological evidence suggests that progression to AIDS following infection with HIV-2 is slower than for HIV-1, however, atypical cases of relatively rapid progressing cases of HIV-2 infection have been observed in The Gambia. The nature of the humoral responses directed at the envelope glycoprotein of HIV-2 in these atypical progressing patients and more typical long term non-progressors was examined in order to assess the importance of envelope specific humoral response with respect to disease course during HIV-2 infection.

METHODS: Humoral response to whole HIV-2 antigens was assessed by Serodia-HIV1/2 passive particle-agglutination test, and surface envelope glycoprotein by EIA on recombinant mammalian expressed surface envelope glycoprotein (rgp105) derived from the Gambian isolate HIV-2ISY/6669. To examine in further detail the nature of the humoral response directed at the envelope glycoprotein of HIV-2, mapping of seroreactive linear epitopes in gp160 was performed using 188 overlapping 12 mer oligopeptides modeling HIV-2ISY/6669.

RESULTS: We found no strong difference between progressors and non-progressors with regard to humoral response to either whole HIV-2 antigens or rgp105. However, when linear epitope reactivity profiles of progressor and non-progressor patients were compared two peptides, both representing regions within the gp36 transmembrane region, were found to be differentially recognised. Further verification using additional serum samples and linear peptides in an EIA format showed the humoral response to one of these peptides, aminoacids 645-656 (YELQKLNSWDVF), to be elevated in: non-progressing patients when compared to progressors (P = 0.09), patients with CD4% of greater than 28% compared to less than 14% (P = 0.004) and patients with undetectable viral RNA compared to those with greater than 5000 copies/ml (P = 0.003). This peptide corresponds to a known broadly neutralizing determinant in HIV-1 that also correlates with disease stage and progression.

CONCLUSIONS: We report elevated humoral response to a linear epitope in HIV-2 envelope in non-progressing HIV-2 patients. The influence that this response has on phenotypic expression of the virus and pathogenicity is under investigation.

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