From the Departments of Laboratory Medicine and Pathology, Medicine, and Pediatrics, University of Minnesota Medical School, and the AIDS Clinical Trials Unit, Minneapolis (A.E., K.J.S., H.H.B.); the Naval Medical Research Institute and Division of Retrovirology, Walter Reed Army Institute of Research, Washington, D.C. (D.L.M.); the Henry M. Jackson Foundation Research Laboratory, Rockville, Md. (F.E.M.); Group Health Inc., Riverside Medical Center, Minneapolis (D.G.S.); and St. Paul Ramsey Medical Center, St. Paul, Minn. (K.H.). Address reprint requests to Dr. Balfour at Box 437 UMHC, Harvard St. at E. River Rd., Minneapolis, MN 55455.Supported by grants (AM13083 and AI27761) from the National Institutes of Health and by grants from the Minnesota Medical Foundation. The opinions expressed herein are those of the authors and do not necessarily reflect those of the Department of the Army, the Department of the Navy, or the Department of Defense.Presented at the 32nd Interscience Conference on Antimicrobial Agents and Chemotherapy, Anaheim, Calif., October 13, 1992.