BROADLY REACTIVE HIV-2 AND SIVMAC SPECIFIC ANTIBODY-DEPENDENT CELLULAR CYTOTOXICITY IN IMMUNIZED AND INFECTED CYNOMOLGUS MONKEYS

Antibody-dependent cellular cytotoxicity (ADCC) was analysed in groups of cynomolgus monkeys that had been immunized with either HIV-2 (stra ins SBL6669 or SBL-K135) or SIVmac. HIV-2- and SIVmac-infected monkeys were also studied for ADCC. Sequential serum samples were collected f rom the animals, which were followed for 1 to 3 years. Sera from the H IV-2-immunized monkeys had ADCC against both homologous and heterologo us HIV-2 strains as well as cross-reactivity against SIVmac-infected t arget cells. This broadly reactive ADCC response could be detected wit hin the first weeks after immunization. Homologous ADCC was also seen in seven of eight SIVmac-immunized monkeys which were all protected fr om later challenge with SIVmac or SVsm. ADCC titres sometimes decrease d after a few months if the immunized monkeys were not boosted whereas most of the HIV-2- and SIVmac-infected monkeys developed a rapid and persistent ADCC response. The presence of ADCC, like the presence of n eutralization in previous studies, did not predict whether the immuniz ed monkeys would be protected upon challenge with line virus.