Understanding HIV infection for the design of a therapeutic vaccine. Part II: Vaccination strategies for HIV.

HIV infection leads to a gradual loss CD4(+) T lymphocytes comprising immune competence and progression to AIDS. Effective treatment with combined antiretroviral drugs (cART) decreases viral load below detectable levels but is not able to eliminate the virus from the body. The success of cART is frustrated by the requirement of expensive lifelong adherence, accumulating drug toxicities and chronic immune activation resulting in increased risk of several non-AIDS disorders, even when viral replication is suppressed. Therefore, there is a strong need for therapeutic strategies as an alternative to cART. Immunotherapy, or therapeutic vaccination, aims to increase existing immune responses against HIV or induce de novo immune responses. These immune responses should provide a functional cure by controlling viral replication and preventing disease progression in the absence of cART. The key difficulty in the development of an HIV vaccine is our ignorance of the immune responses that control of viral replication, and thus how these responses can be elicited and how they can be monitored. Part one of this review provides an extensive overview of the (patho-) physiology of HIV infection. It describes the structure and replication cycle of HIV, the epidemiology and pathogenesis of HIV infection and the innate and adaptive immune responses against HIV. Part two of this review discusses therapeutic options for HIV. Prevention modalities and antiretroviral therapy are briefly touched upon, after which an extensive overview on vaccination strategies for HIV is provided, including the choice of immunogens and delivery strategies.