Objective:

Several lines of evidence suggest that the immune system may control HIV-1 replication, but that it could fail in the long term. Strategies aimed to elicit specific immune responses may enable patients to contain virus replication.

Methods:

HIV-1-infected patients were randomized to continue either their antiviral therapy alone (controls; n= 37) or with four boosts of vaccination combining ALVAC-HIV (vCP1433) and Lipo-6T vaccines (weeks 0, 4, 8, 12) followed by three cycles of subcutaneous interleukin-2 (weeks 16, 24, 32)(Vac-IL-2 group; n= 34).

Results:

Of the Vac-IL-2 group, 15/32 (47%) exhibited a stable HIV p24 antigen-proliferative response compared with 8/33 (24%) controls (P= 0.049). After vaccination, 19/33 (58%) of the Vac-IL-2 group exhibited a multiepitopic HIV-1-specific CD4 cell proliferative response compared with 9/36 (25%) of controls (P= 0.006). The breadth and the magnitude of HIV-specific interferon-γ-producing CD8 T cells improved in the Vac-IL-2 group. After stopping antiviral drugs, 24% of the Vac-IL-2 group lowered their viral set point compared with 5% of controls (P= 0.027). Logistic-regression analysis demonstrated that vaccine-elicited immunological responses were predictive of virological control (P= 0.046 and 0.014 for stable and multiepitopic CD4 T cell responses, respectively).

Conclusion:

This study provides proof of the concept that therapeutic immunization before antiviral drug cessation may contribute to the containment of HIV replication.