Analysis of the Impact of HCV Treatment by Last Generation Direct Antiviral Agents (DAA) on Antiviral Immunity and HIV DNA Reservoir in Coinfected HIV-HCV Patients

Spontaneous recovery of patients infected with HCV is related to the development of a cytotoxic immune response that is executed by specialized white blood cells, the CD8+ T cells, which develop a virus-specific response. In addition, the natural killer (NK) cells provide a first-line innate cytotoxic response, which is pivotal for the spontaneous clearing of HCV. In patients where HCV infection settles chronically, CD8+ T lymphocytes and NK cells fall into a state of anergy induced by chronic viral challenge. This anergic state is also found in the case of HIV infection and exacerbated by HIV-HCV coinfection. The first therapeutic strategies against HCV were based on a treatment with interferon alpha, which had an antiviral but also immunosuppressive effect. In fact, this therapeutic strategy was unable to help the recovery of the patient's immune system that would be expected after HCV cure. However, interferon-free therapeutic strategies combining first generation direct antiviral agents (DAA) showed a positive effect on HCV antiviral immunity, by enhancing the proliferative response of CD8+ T cells and the cytotoxic and proinflammatory responses of NK cells in HCV monoinfected patients (4, 5). Since HCV-targeted therapies based on combinations of the latest generation of DAA have nearly 100% cure rates and enable faster viral suppression over shorter treatment times, a positive impact of these regimens on antiviral immunity is plausible. This possibility would be particularly interesting in HIV-HCV co-infected patients, where reactivation of the innate antiviral immunity may contribute to immune defenses against both viruses. Moreover, it has been previously reported a moderate but significant and sustained decline of HIV-1 DNA in CD4 T cells from HIV-1/hepatitis C virus-coinfected patients receiving highly active antiretroviral therapy and treated with IFN alpha/ribavirin. To date, the real impact on antiviral immunity of treatment as well as on HIV reservoir