1. Department of Virology,1
2. Division of Bioanalysis and Drug Metabolism,2 and
3. Department of Biochemistry,3 Glaxo Wellcome, Inc., Research Triangle Park, North Carolina 27709;
4. The Marjorie B. Kovler Viral Oncology Laboratories, University of Chicago, Chicago, Illinois 60637;4 and
5. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 021155