Transmission of HIV to the placenta, fetus and mother and implications of gametic infection.

Therapeutic interventions and public education are reducing pediatric AIDS cases in developed countries, but the number of HIV-infected women and children is still a major global concern. The finding that human sperm-associated HIV can be transmitted to oocytes following in vitro fertilization provides a novel viewpoint from which to consider not only the problem of HIV transmission to children but also transmission to women. In the present paper we will first discuss some recent findings that offer new perspectives on the role of the placenta, and particularly the trophoblast, in maternal-fetal transmission of HIV. Results will be presented showing that cell-mediated infection of syncytiotrophoblast cells requires direct contact between infected lymphocytes and trophoblast. We will also discuss possible routes of transmission of HIV to both mothers and their offspring in the light of data providing evidence of gametic infection. These hypothetical routes include trophoblast-mediated infection of maternal uterine cells during implantation and trophoblast-mediated infection of maternal blood cells during pregnancy. Clearly, more studies are needed in order to assess the significance and relative contribution of these routes in the transmission of HIV.