AEGiS-14IAC: HIV-1-specific IgA antibodies in exposed yet HIV-1 Sero-negative female Ugandans.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

HIV-1-specific IgA antibodies in exposed yet HIV-1 Sero-negative female Ugandans.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. MoOrA1053)

Kebba A, Trabattoni D, Kaleebu P, Clerici M, Imami N, Gotch F, Whitworth J
Medical Research Council's Programme on AIDS in Uganda, Uganda Virus Research Institute, Entebbe, Uganda

BACKGROUND: The presence of HIV-1-specific genital mucosal antibodies in HIV-1 sero-positive (SP) females establishes that the virus elicits genital humoral immune responses. Their presence in exposed yet HIV-1 sero-negative (ESN) females would suggest their relevance in AIDS vaccine design since they may be contributing to the mediation of resistance to HIV-1 infection in ESNs.

METHODS: 8 ESN females with a history of frequent unprotected sexual intercourse with an HIV-1 infected spouse and 7 SP females were identified from among HIV-1 sero-discordant couples. Vaginal secretions were collected and assayed for HIV-1-gp160-specific IgA and IgG antibodies using a modified enzyme immunosorbent assay. The plasma viral load (pVL) of the SP females as well as the SP male spouses of the ESN females was determined using the Roche Amplicor assay.

RESULTS: All ESN females were negative on two HIV serological tests for plasma IgG and negative for HIV-1 proviral DNA. Evidence for exposure to HIV-1 infection was deduced from the presence of systemic HIV-1-specific interferon-gamma+ CD69+ CD4+ T lymphocytes in 3/5 ESNs tested. Gp160-specific IgG was not found in vaginal secretions from ESN females, whereas such antibody was present in vaginal secretions from 6/7 SP females. There was a tendency in ESNs for gp160-specific IgA absorbencies to increase concurrently with increasing pVL in their infected spouse, whereas IgA absorbencies in SP females were inversely correlated with autologous pVL.

CONCLUSION: The presence of HIV-1-gp160-specific IgA antibodies in the absence of similarly specific IgG antibodies is strongly suggestive of the importance of IgA in the mediation of apparent resistance in ESN females. The findings also support the relevance of the induction of genital humoral mucosal immunity in AIDS vaccine design.

Keywords: AEGIS, HIV-1, HIV Antibodies, HIV Seropositivity, HIV Infections, AIDS Vaccines, Viral Load, HIV Antigens, HIV Seronegativity, HIV Envelope Protein gp160, Vagina, Immunoglobulin A, HIV, Antibodies, Anti-HIV Agents, Immunoglobulin G, Human, Female, Male, immunology

020707
MoOrA1053