Animal cells secrete small vesicles (~50-250 nm diameter) that have the same topology as the cell. These vesicles, known as exosomes and microvesicles (EMVs), can be taken up by neighboring cells, completing a pathway of intercellular vesicle traffic. Our laboratory studies the molecular mechanisms of EMV biogenesis and uptake, and their contributions to cell polarity, cell:cell interactions, and intercellular signaling. Furthermore, we study the ways in which HIV and other retroviruses use the exosome biogenesis pathway for the formation of infectious virions, and the consequences of their EMV origin. Currently, we are investigating the following questions: What are the cis-acting signals that target proteins to secreted vesicles? What are the trans-acting factors that mediate EMV biogenesis? What are the mechanisms of EMV biogenesis? How does HIV exploit the EMV biogenesis pathway? How do infection-boosting, protease-generated ligands promote HIV infectivity?