What are the primary antibody types involved in protection against poliovirus?

• A. Mucosal IgA only
• B. Neutralizing antibodies (serum IgG) and mucosal IgA
• C. Serum IgG only
• D. IgE

Answer: (B)

Protection against poliovirus relies on antibodies that work both at the entry point and in circulation. The virus is swallowed and first replicates in the gut, so mucosal secretions containing IgA neutralize the virus at the intestinal surface, reducing infection at its source. At the same time, neutralizing antibodies circulating in the blood, mainly serum IgG, prevent viremia and safeguard against paralysis if the virus reaches the central nervous system. Because effective protection requires both stopping the virus in the gut and stopping its spread in the body, the key antibody types are neutralizing antibodies in serum (primarily IgG) and mucosal IgA. IgE is not involved in poliovirus protection, and having only one of the two arms leaves gaps in immunity.