CD4 and infection: To clarify the cellular and molecular basis of the immunomodulatory action of VCGs, the present study will: a) investigate the ability of mouse bone marrow-derived DCs (BMDCs) to take up and internalize VCGs; b) determine the effect of internalized VCGs on DC activation, maturation and differentiation and; c) evaluate the immunomodulatory ability of VCGs to enhance the functional capacity of BMDCs to present chlamydial antigen to naïve and infection-sensitized CD4+ T cells and stimulate T cell proliferation.