What is the primary site for poliovirus multiplication?

• A. The lining ('mucous membrane') of the intestines.
• B. The brain
• C. The liver
• D. The lungs

Answer: (A)

Poliovirus is an enterovirus that multiplies mainly in the mucosal lining of the gut. After exposure, it replicates in the intestinal mucosa (and the associated gut lymphoid tissue), which drives shedding in stool and transmission via the fecal-oral route. This intestinal replication is what establishes infection, while the brain becomes involved only in a minority of cases when the virus spreads to the nervous system. The liver and lungs are not primary sites of multiplication for poliovirus. So, the intestinal lining is the best answer because it is where the virus primarily replicates.