Abstract: A family of pyrazolo[3,4-d]pyrimidine derivatives (SPPs) with different substituents on the pyrimidine and pyrazolo rings have been characterized with a panel of tests demonstrating their effects in cell proliferation, toxicity, apoptosis and inhibition of virus replication. We have identified compounds and molecular structures suitable for the treatment of viral infection because they have antiviral activity, anti-proliferative activity or, preferably, both so that, as a single molecule, they both limit T cell hyperactivation and inhibit virus replication. These compounds are not toxic at effective concentrations and are poorly apoptotic. Other nontoxic compounds within this family with excellent anti-proliferative and apoptotic features are potentially effective as anti-cancer drugs.