mRNA-based dendritic cell vaccination induces potent antiviral T-cell responses in HIV-1-infected patients

In an effort to raise protective antiviral immunity, dendritic cell immunotherapy was evaluated in six adults infected with human immunodeficiency virus (HIV)-1 and stable under highly active antiretroviral therapy (HAART).

Autologous monocyte-derived dendritic cells electroporated with mRNA encoding Gag and a chimeric Tat-Rev-Nef protein were administered, whereas patients remained on HAART. Feasibility, safety, immunogenicity and antiviral responses were investigated.

Dendritic cell vaccine preparation and administration were successful in all patients and only mild adverse events were seen. There was a significant increase post-dendritic cell as compared to pre-dendritic cell vaccination in magnitude and breadth of HIV-1-specific interferon (IFN)-γ response, in particular to Gag, and in T-cell proliferation. Breadth of IFN-γ response and T-cell proliferation were both correlated with CD4(+) and CD8(+) polyfunctional T-cell responses. Importantly, dendritic cell vaccination induced or increased the capacity of autologous CD8(+) T cells to inhibit superinfection of CD4(+) T cells with the vaccine-related IIIB virus and some but not all other HIV-1 strains tested. This HIV-1-inhibitory activity, indicative of improved antiviral response, was correlated with magnitude and breadth of Gag-specific IFN-γ response.

Therapeutic immunization with dendritic cells was safe and successful in raising antiviral cellular immune responses, including effector CD8(+) T cells with virus inhibitory activity. The stimulation of those potent immunological and antiviral effects, which have been associated with control of HIV-1, underscores the potential of dendritic cell vaccination in the treatment of HIV-1. The incomplete nature of the response in some patients helped to identify potential targets for future improvement, that is increasing antigenic spectrum and enhancing T-cell response.