How do NNRTIs differ from NRTIs in their mechanism of action?

NNRTIs, or non-nucleoside reverse transcriptase inhibitors, differ from NRTIs, or nucleoside reverse transcriptase inhibitors, primarily in their mechanism of action against HIV's reverse transcriptase. NNRTIs are unique in that they bind to a specific non-nucleoside site on the reverse transcriptase enzyme. This binding induces a conformational change in the enzyme, inhibiting its function and preventing the conversion of viral RNA into DNA, a critical step in the replication of HIV.

In contrast, NRTIs mimic the building blocks of DNA and are incorporated into the viral DNA chain during replication. They act by causing chain termination once incorporated, which effectively halts the synthesis of viral DNA. This distinction in how NNRTIs bind and affect reverse transcriptase versus how NRTIs function underscores their different roles in antiretroviral therapy.

Understanding this difference is key for recognizing how various antiviral medications can be targeted and utilized in the treatment of HIV, focusing on the specific mechanisms that inhibit the virus's ability to replicate and spread.