Antiviral Drugs Nucleoside and nucleotide analogs c c Guanine HN HN c一N CH CH HN一C C-N NoN-C N N C-N HOCH2 HOCH c HO Deoxyguanosine Acyclovir Viral Coll cell thymidine thymidine kinase thymidine kinase kinase Acyclovir Acycloguanosine Acycloguanosine Acycloguanosine monophosphate diphosphate triphosphate