Which term is used for an agent that specifically acts against viruses?

The term that is used for an agent that specifically acts against viruses is "Virucidal." This refers to substances or treatments that are effective in disabling or destroying viruses, thus preventing them from replicating and causing infection. Virucidal agents are crucial in various settings, including healthcare, where controlling viral infections is a priority.

In contrast, other terms in the options relate to different types of microorganisms or actions. Fungicidal refers to agents that kill fungi, which wouldn't be effective against viruses. MRSA stands for Methicillin-resistant Staphylococcus aureus, a specific type of bacteria that is resistant to certain antibiotics, making it relevant only in the context of bacterial infections rather than viral ones. Bactericidal refers to agents that kill bacteria, which again would not be effective against viral pathogens. Understanding these distinctions helps clarify the specific action of virucidal agents in infection control and public health.