What is the role of proteases encoded by poliovirus?

• A. To replicate the viral RNA genome
• B. To cleave the viral polyprotein into functional proteins and shut down host protein synthesis
• C. To form the viral capsid
• D. To enhance host cell transcription

Answer: (B)

Poliovirus proteins are produced as a single, long polyprotein that must be cut into functional viral proteins by viral proteases. These proteases, mainly 2A and 3C, cleave at specific sites to generate the structural and nonstructural components needed for replication. In addition, the 2A protease can target host cell factors like eIF4G, shutting down host protein synthesis and redirecting the cell’s translation machinery toward viral RNA. This combination—processing the polyprotein into mature viral proteins and suppressing host protein production—best describes the proteases’ role.