Potentiating effect of (2-[2-[(2-amino-1,6-dihydro-6-oxo-9H-purin-9-yl)methyl]-phenyl]ethenyl) -phosphonic acid (MDL 74,428), a potent inhibitor of purine nucleoside phosphorylase, on the antiretroviral activities of 2',3'-dideoxyinosine combined with ribavirin in mice.
