11th International AIDS Conference Vancouver, British Columbia — July 7-12, 1996

Int Conf AIDS 1996 Jul 7-12; 11:13 (abstract no. We.A.392)
Neildez O, Le Grand R, Caufour P, Cheret A, Matheux F, Theodoro F, Vaslin B, Dormont D; Service de Neurovirologie, Commissariat a l'Energie Atomique, DRM, DSV, SSA, Fontenay-aux-Roses, France. Fax: (33-1) 46 54 77 26.

OBJECTIVE: To characterize the evolution of virological and immunological parameters after experimental vaginal atraumatic exposure of macaques to an SIVmac 251 cell free virus stock.

METHODS: Three groups of four cynomolgus macaques, previously traited by oestradiol, were inoculated atraumatically into the vagina with 1 ml of the virus stock containing 2.103 (group 1), 2.102 (group 2) and 20 (group 3) intravenous-AID50% diluted in PBS or human seminal plasma. The virus stock is a cell-free supernatant containing a pathogenic biological isolate of SIVmac251 produced by rhesus PBMC. Virus was detected in fresh PBMC and vaginal washes (V.W) by PCR and cocultures assays. Antibody response was investigated in plasma and V.W supernatants.

RESULTS: Vaginal infection of macaques could be achieved after a single exposure with high (group 1) and intermediate (group 2) doses of virus. Monkeys from group 3 had no evidence of infection. Seminal plasma seemed to have no effect on the infectivity of the virus stock. After vaginal inoculation (IVag), our virus stock was less infectious than after IV inoculation but more infectious than after intrarectal (IR) inoculation. Furthermore, virological and immunological parameters were different from those observed after IV or IR inoculation: in groups 1 and 2 virus was persistently recovered in half of the animals from PBMC and V.W whereas, in the other half of the macaques, virus was only transiently detected. High antibody amounts in plasma correlate with high level of infection. In V.W only a weak and transient antibody response was observed as soon as 7 days p.i. in 4/12 animals. This response was irrespective of the dose inoculated and to the level of infection. Later, anti-SIV antibodies were detected in significant amount in vaginal secretions from infected monkeys mainly during menses.

CONCLUSION: IVag inoculation of macaques with SIVmac251 differs from IV or IR inoculation. Two patterns were observed irrespective of the doses of virus inoculated: early and persistent positive virus detection (50%), late and transient infection (50%). Humoral response correlates with virus detection; however, there was no correlation between antibody titers, inoculated doses and evolution to AIDS. Furthermore, no stable mucosal antibody response was detected despite of the presence of virus in lymphocytes from V.W and LNMC.

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WeA392

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