Immunity to HIV

HIV is the cause of a worldwide pandemic. Infection with HIV leads to systemic depletion of CD4⁺ T lymphocytes that are required to protect against infection and the development of tumors. The loss of these cells results in acquired immunodeficiency syndrome (AIDS). The immune response to HIV infection is manifold and is comprised of innate and acquired mechanisms. Innate mechanisms include natural killer cells and macrophages, and acquired mechanisms include cytotoxic T cell responses, neutralizing antibodies, and protective nonneutralizing antibodies. In spite of this defense, without treatment, HIV-infected individuals eventually succumb to infection, develop AIDS, and die. Potent antiretroviral therapy has enabled many people infected with HIV to survive and live productive lives; however, antiretroviral drugs are costly, must be taken daily, and can have severe side effects. Development of a protective vaccine is critical if we hope to curb the spread of HIV. New approaches for vaccine development that include a clearer understanding of how to trigger the immune mechanisms that protect against infection and disease protection are key in this effort.