While several nucleoside analogs have made it to market, a number have failed in late stage trials due to severe toxicity. But work published in last week's Proceedings of the National Academy of Sciences may make it easier to design nucleoside analogs with better safety profiles.

Nucleoside analogs are designed to be similar to deoxyribonucleotides, the building blocks of DNA. They are used to treat viral infections including HIV and hepatitis because they bind to the viral reverse transcriptase and halt viral proliferation.