4H-Pyrazolo[3,4-d]pyrimidin-4-one, 6-amino-1,5-dihydro-1-.beta.-D-ribofuranosyl- 6-Amino--1-.beta.-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one 7-Deaza-8-azaguanosine 85426-74-0 AIDS-001493 AIDS001493 Pyrazolopyrimidine nucleoside