The present invention relates to nucleosides of formula I wherein R
1
, R
2
and R
3
are as defined herein that modulateTh1 and Th2 immune activity, methods of using compounds according to formula I, alone or in combination therapy, for treatment of a bacterial or a viral infection, a parasite infestation, a cancer or tumor or an autoimmune disease and compositions containing prodrugs of the nucleoside of formula Ia.
1