Viral DNA synthesis in HIV-1-infected cells, measured by real-time PCR. Infections were carried out using a vector that replicates using wild-type RT (the active-site mutant D110E was included as a negative control) in the presence or absence of an inhibitory compound. Results for infections carried out in the absence of an inhibitor are shown. The inhibitors tested were 4′-C-methyl-2′-deoxyadenosine, 4′-C-ethyl-2′-deoxyadenosine, and AZT. Mock transfections and the D110E RT mutant were used as DNA-negative controls. DNA products corresponding to initiation (A), minus-strand transfer (B), plus-strand transfer (C), and Gag (D) are shown.