The immune response to HIV

HIV-1 elicits vigorous humoral and cell-mediated responses: these fail to clear the infection but contain viral replication for several years, at the expense of ongoing immune activation and CD4+ T cell loss. Over the past 25 years, several mechanisms by which HIV-1 and other AIDS viruses evade host immune responses have been elucidated. Genetic variability, rapid establishment of a reservoir of latently-infected long-lived CD4+ T cells and resistance to neutralization by antibodies are formidable obstacles to the development of a preventive vaccine. This has been highlighted by the disappointing results of recent efficacy trials. However, this remains an urgent priority, as available prevention strategies have been insufficient to stop the global epidemic. Rare individuals who show no signs of progression after one or two decades of infection indicate that immune control of HIV-1 is possible and may inform vaccine design.