An in vitro model of trophoblast will be developed which will permit research into many aspects of placental function as it relates to maternal HIV infection. The trophoblast will be maintained in tissue culture in a bicameral chamber providing independent access to the apical (maternal) and basal (fetal) surfaces of the trophoblast. The criteria for a successful preparation will include tests of barrier function (electrical resistance, restricted transfer of inulin and other molecules, microscopic evidence of a continuous monolayer) and tests of polarity (differentiation into apical and basolateral domains on EM, directed extrusion of virions and preferential uptake of transferrin from the apical surface). Three cell types will be used for the model: transformed trophoblast and primary trophoblast isolated from term and from first trimester placenta. The models will be subjected to tests designed to investigate two of its major roles: the transfer of nutrients to the fetus and the synthesis and secretion of hormones for the maintenance of pregnancy. The potential toxicity of anti-HIV drugs will be explored by exposing trophoblast to the drug and then re-testing its function. The transfer and metabolism of the HIV drugs will also be studied taking advantage of the polarity of the model. Concurrently the usefulness of the model for the study of immunological questions concerning AIDS and other intrapartum infections will be explored. The expression of Fc receptors and the transepithelial transfer of IgG will be measured. Introduction of Fc receptors into trophoblast by recombinant techniques will be undertaken to amplify this function if necessary. The model will be applied to questions pertinent to the manifestation of disease in the fetus such as the transfer of specific antibodies, of viral antigens and infectious agents and of complexes of antigens and antibodies.