Preexisting poliovirus-specific IgA in the circulation correlates with protection against virus excretion in the elderly.

Background: Epidemiological studies have indicated that at least 10% of the Dutch elderly do not have poliovirus serotype-specific neutralizing antibody titers and might be at risk for poliovirus infection. Previously we established that memory immunity does not protect the elderly against poliovirus replication. In this study, we investigated whether preexisting immunoglobulin (Ig) A protects against poliovirus infection.