Which antiviral agent works by inhibiting viral RNA polymerase?

Ribavirin is the antiviral agent that works by inhibiting viral RNA polymerase. This mechanism is crucial for its activity against various viruses, particularly hepatitis C virus and certain viral hemorrhagic fevers. By inhibiting the action of RNA polymerase, ribavirin interferes with the virus's ability to replicate its RNA genome, thereby reducing the viral load and helping the body's immune system control the infection.

In contrast, oseltamivir and zanamivir are neuraminidase inhibitors that work specifically against influenza viruses by preventing the release of new viral particles from infected cells, which does not involve inhibition of RNA polymerase. Tenofovir, on the other hand, is a reverse transcriptase inhibitor primarily used against HIV and hepatitis B, targeting the enzyme responsible for converting viral RNA into DNA rather than RNA polymerase. Thus, ribavirin is distinguished by its direct action on viral RNA synthesis through polymerase inhibition.