Antiretroviral enantiomeric nucleotide analogs

A method of achieving a human immunodeficiency virus or hepatitus B virus antiviral effect in a mammal in need of such treatment which comprises administering to said mammal an antivirally effective amount of a compound of the formula ##STR13## including physiologically acceptable salts of such compound, wherein said compound of Formula IA is the R isomer substantially free of its enantiomer and wherein B is a purine moiety substituted at the 6 position by amino, alkylamino, dialkylamino, or aralkylamino, and wherein R is H, and wherein alkyl is straight or branched chain C1-C6, aryl is a C6-C10 aromatic group, and aralkyl is a C1-C6 straight or branched chain alkyl-C6-C10 aromatic group.