Use of well-defined HIV-derived epitopes to evaluate CD4(+) and CD8(+) T cell responses in patients with chronic HIV-1 infection treated with HAART

Immunological responses and long-term treatment interruption after human immunodeficiency virus type 1 (HIV-1) lipopeptide immunization of HIV-1-infected patients: the LIPTHERA study

We studied the time course of immunological and virological markers after highly active antiretroviral therapy (HAART) interruption in chronically human immunodeficiency virus type 1 (HIV-1)-infected patients immunized with an HIV lipopeptide preparation. In a prospective open pilot study, 24 HIV-1-infected HAART-treated patients with undetectable plasma viral loads (pVLs) and CD4(+) T-cell counts above 350/mm(3) were immunized at weeks 0, 3, and 6 with a candidate vaccine consisting of six HIV lipopeptides. At week 24, patients with pVLs of <1.7 log(10) copies/ml were invited to stop taking HAART. Antiretroviral therapy was resumed if the pVL rose above 4.47 log(10) copies/ml and/or if the CD4(+) cell count fell below 250/mm(3). Immunological and virologic parameters were studied before and after HAART interruption. The median baseline and nadir CD4(+) cell counts were 482 (interquartile range [IQR], 195 to 826) and 313 (IQR, 1 to 481)/mm(3), respectively. New specific CD8(+) cell responses to HIV-1 epitopes were detected after immunization in 13 (57%) of 23 assessable patients. Twenty-one patients were evaluated 96 weeks after HAART interruption. The median time to pVL rebound was 4 weeks (IQR, 2 to 6), and the median peak pVL was 4.26 (IQR, 3 to 5) log(10) copies/ml. Thirteen of these 21 patients resumed HAART a median of 60 weeks after immunization (IQR, 9.2 to 68.4 weeks), when the median pVL was 4.8 (IQR, 2.9 to 5.7) log(10) copies/ml and the median CD4(+) cell count was 551 (IQR, 156 to 778)/mm(3). Eight patients were still off therapy at 96 weeks, with a median pVL of 4 (IQR, 1.7 to 4.6) log(10) copies/ml and a median CD4(+) cell count of 412 (IQR, 299 to 832)/mm(3). No clinical disease progression had occurred. Despite the lack of a control arm, these findings warrant a randomized study of therapeutic vaccination with HIV lipopeptides followed by long-term HAART interruption in AIDS-free chronically infected patients.

Long-Term Highly Active Antiretroviral Therapy in Chronic HIV-1 Infection: Evidence for Reconstitution of Antiviral Immunity

In this study we investigated the long-term effect of highly active antiretroviral therapy (HAART) on HIV-specific CD4+ T-cell responses in comparison with virus-specific CD4+ T-cell responses against the persistent herpes viruses cytomegalovirus (CMV) and Epstein-Barr virus (EBV). To this end, HIV- and herpes virus-specific cellular immune responses were measured longitudinally in 10 seroconverters with long-term follow-up including 55 months of successful suppression of viral load by HAART. HIV- and CMV-specific CD4+ T cells producing interferon-γ (IFNγ) or interleukin-2 (IL-2) were analysed as well as proliferative capacity. EBV-specific CD4+ T cells were determined using a 12-day ex vivo assay. Initiation of HAART resulted in a transient increase of HIV-specific IL-2+IFNγ+CD4+ T cells and, to a lesser extent, IL-2+CD4+ T cells. Long-term HAART resulted in an increase in HIV-, CMV- and EBV-specific CD4+ T-cell proliferative capacity. The increase in HIV- and herpes-virus-specific CD4+ T-cell proliferative capacity after 55 months of HAART suggests that the improved proliferative response is not specific for HIV, but reflects a more general improvement of antiviral immune responses, which is induced by HAART.