Methods and Compositions involving the administration of guanosine, identified as Toll like receptor (TLR) 2 and 4 agonists, that will be useful for enhancing the potency of vaccine and cancer immunotherapies are disclosed. Method of preventing and treating cancer and infection by administration of guanosine or pro-drugs of guanosine, or a precursor of guanosine are also disclosed. Compositions of guanosine or a pro-drug of guanosine or precursor of guanosine may be formulated as pharmaceutical dosage forms and components can be assembled as kits. Methods for activating TLRs with guanosine to enhance an immune response and to potentiate/augment antiviral, antibacterial or anticancer effects of other antiviral, anti-bacterial and anticancer therapeutic agents are also disclosed.
