What is a key function of interferons in antiviral defense?

What is a key function of interferons in antiviral defense?

• A. Enhance phagocytosis of pathogens
• B. Inhibit protein synthesis by degrading viral mRNA
• C. Directly lyse infected cells
• D. Block viral attachment to host cells

Answer: (B)

Interferons create an antiviral state in both the producing cells and neighboring cells by turning on enzymes that cripple viral replication. The key effect is to block viral protein production, which is central to stopping the infection. This happens when interferons induce PKR, which phosphorylates the translation initiation factor eIF2α, preventing viral mRNA from being efficiently used to make proteins. They also induce RNase L, an enzyme that degrades viral RNA, cutting down the templates viral proteins need. Together, these actions drastically reduce viral protein synthesis and replication. That’s why the option describing degradation of viral RNA to inhibit protein synthesis aligns with the main antiviral action of interferons. Other choices don’t capture this intracellular shutdown of viral replication—interferons don’t directly enhance phagocytosis, cause direct lysis of infected cells, or block viral attachment themselves.

Interferons create an antiviral state in both the producing cells and neighboring cells by turning on enzymes that cripple viral replication. The key effect is to block viral protein production, which is central to stopping the infection. This happens when interferons induce PKR, which phosphorylates the translation initiation factor eIF2α, preventing viral mRNA from being efficiently used to make proteins. They also induce RNase L, an enzyme that degrades viral RNA, cutting down the templates viral proteins need. Together, these actions drastically reduce viral protein synthesis and replication.

That’s why the option describing degradation of viral RNA to inhibit protein synthesis aligns with the main antiviral action of interferons. Other choices don’t capture this intracellular shutdown of viral replication—interferons don’t directly enhance phagocytosis, cause direct lysis of infected cells, or block viral attachment themselves.