What is the effect of NRTIs on viral RNA?

NRTIs, or nucleoside reverse transcriptase inhibitors, play a crucial role in the treatment of viral infections, particularly HIV. Their main mechanism of action is to interfere with the replication cycle of the virus by inhibiting the reverse transcriptase enzyme. This enzyme is responsible for converting viral RNA into DNA, a critical step in the viral life cycle because the viral RNA must be reverse transcribed to DNA before it can integrate into the host's genome.

By preventing this conversion of RNA into DNA, NRTIs effectively halt the replication of the virus. This disruption reduces the viral load and helps manage the infection. The failure of the RNA to be converted means that subsequent steps in the viral replication process, such as integration into the host genome and subsequent production of viral proteins, are also blocked.

The other options don’t accurately describe the primary action of NRTIs: they do not enhance replication, inhibit translation, or facilitate integration; instead, their primary role is clearly in blocking the conversion of viral RNA into DNA. This makes option B the accurate reflection of the effect of NRTIs on viral RNA.