What is the role of neutralizing antibody titers in polio protection?

• A. They do not correlate with protection.
• B. They correlate with protection against clinical poliomyelitis, and immunity to all three serotypes is needed to prevent paralysis.
• C. They are only important for intestinal immunity.
• D. They are irrelevant to protection.

Answer: (B)

Neutralizing antibody titers reflect the immune system’s ability to block poliovirus from infecting cells, and they are a key correlate of protection against poliomyelitis. Protection against paralysis depends on having protective levels of these antibodies against all three poliovirus serotypes, because infection with any one serotype can cause poliomyelitis if there isn’t sufficient neutralizing antibodies for that serotype. So, high titers against each serotype mean individuals are protected from disease, not just from intestinal infection.