[Show abstract][Hide abstract] ABSTRACT: With the recent demonstration in the RV144 Thai trial that a vaccine regimen that does not elicit neutralizing antibodies or cytotoxic T lymphocytes may confer protection against human immunodeficiency virus type 1 (HIV-1) infection, attention has turned to nonneutralizing antibodies as a possible mechanism of vaccine protection. In the current study, we evaluated the kinetics of the antibody-dependent cell-mediated cytotoxicity (ADCC) response during acute and chronic SIVmac251 infection of rhesus monkeys. We first adapted a flow cytometry-based ADCC assay, evaluating the use of different target cells as well as different strategies for quantitation of activated natural killer (NK) cells. We found that the use of SIVmac251 Env gp130-coated target cells facilitates analyses of ADCC activity with a higher degree of sensitivity than the use of simian immunodeficiency virus (SIV)-infected target cells; however, the kinetics of the measured responses were the same using these different target cells. By comparing NK cell expression of CD107a with NK cell expression of other cytokines or chemokine molecules, we found that measuring CD107a expression is sufficient for evaluating the anti-SIV function of NK cells. We also showed that ADCC responses can be detected as early as 3 weeks after SIVmac251 infection and that the magnitude of this antibody response is inversely associated with plasma viral RNA levels in animals with moderate to high levels of viral replication. However, we also demonstrated an association between NK cell-mediated ADCC responses and the amount of SIVmac251 gp140 binding antibody that developed after viral infection. This final observation raises the possibility that the antibodies that mediate ADCC are a subset of the antibodies detected in a binding assay and arise within weeks of infection.
Full-text · Article · Jul 2011 · Journal of Virology
[Show abstract][Hide abstract] ABSTRACT: Antibody-dependent cell-mediated viral inhibition (ADCVI) is an attractive target for vaccination because it takes advantage of both the anamnestic properties of an adaptive immune response and the rapid early response characteristics of an innate immune response. Effective utilization of ADCVI in vaccine strategies will depend on an understanding of the natural history of ADCVI during acute and chronic human immunodeficiency virus type 1 (HIV-1) infection. We used the simian immunodeficiency virus (SIV)-infected rhesus monkey as a model to study the kinetics of ADCVI in early infection, the durability of ADCVI through the course of infection, and the effectiveness of ADCVI against viruses with envelope mutations that are known to confer escape from antibody neutralization. We demonstrate the development of ADCVI, capable of inhibiting viral replication 100-fold, within 3 weeks of infection, preceding the development of a comparable-titer neutralizing antibody response by weeks to months. The emergence of ADCVI was temporally associated with the emergence of gp140-binding antibodies, and in most animals, ADCVI persisted through the course of infection. Highly evolved viral envelopes from viruses isolated at late time points following infection that were resistant to plasma neutralization remained susceptible to ADCVI, suggesting that the epitope determinants of neutralization escape are not shared by antibodies that mediate ADCVI. These findings suggest that despite the ability of SIV to mutate and adapt to multiple immunologic pressures during the course of infection, SIV envelope may not escape the binding of autologous antibodies that mediate ADCVI.
Full-text · Article · Mar 2011 · Journal of Virology