Participants come to the NIH Clinical Center a minimum of once every 3 to 4 months for evaluation with a physical examination; blood tests for research purposes, safety, immune status and viral load; and response to any treatment they may be receiving. Other procedures, such as a biopsy, are done only as needed for standard medical practice, and informed consent is obtained before any such procedure is done. Treatment offered is consistent with standard medical practice; no experimental treatments are offered under this protocol.