Poliovirus-specific intestinal antibody responses coincide with decline ofpoliovirus excretion

Antibody responses to poliovirus type 3 were studied in fecal samples of 66 children immunized with 3 doses of enhanced-potency inactivated poliovirus vaccine (E-IPV), followed by 1 dose of monovalent oral poliovirus vaccine (OPV, type 3 Sabin), One fecal sample taken before OPV vaccination and 9 co llected thereafter were tested for neutralizing antibodies by a microneutra lization assay and for class-specific responses by heavy chain-capture radi oimmunoassays, Both neutralizing antibody and IgA responses usually occurre d during the second week and coincided with ceasing of virus excretion or a decrease in the excreted virus titer, Waif of the vaccinees had received a trypsin-modified E-IPV, but their responses did not differ from those of c hildren immunized with the regular E-IPV, These results are in agreement wi th the view that an intestinal antibody response, mainly consisting of IgA, may be involved in the ceasing of a primary poliovirus excretion.