Animation: Mechanisms of Action of Nucleoside Reverse Transcriptase Inhibitors (NRTIs) When HIV viral RNA is released into a host cell, it is reverse transcribed to yield viral DNA. This viral DNA incorporates into the host cell's genome, leading to the production of viral proteins. This animation describes how NRTI drugs work by incorporating themselves into viral DNA as it is being transcribed, and thus, blocking further extension of the viral DNA chain.