Immune-based approaches to the prevention of mother-to-child transmission of HIV-1: active and passive immunization.

Despite more than 2 decades of research, an effective vaccine that can prevent HIV-1 infection in populations exposed to the virus remains elusive. In the pursuit of an HIV-1 vaccine, does prevention of exposure to maternal HIV-1 in utero, at birth or in early life through breast milk require special consideration? This article reviews what is known about the immune mechanisms of susceptibility and resistance to mother-to-child transmission (MTCT) of HIV-1 and summarizes studies that have used passive or active immunization strategies to interrupt MTCT of HIV-1. Potentially modifiable infectious cofactors that may enhance transmission and/or disease progression (especially in the developing world) are described. An effective prophylactic vaccine against HIV-1 infection needs to be deployed as part of the Extended Program of Immunization recommended by the World Health Organization for use in developing countries, so it is important to understand how the infant immune system responds to HIV-1 antigens, both in natural infection and presented by candidate vaccines.