Nasopharyngeal secretory antibody response to poliovirus type 3 virion proteins exhibit different specificities after immunization with live or inactivated poliovirus vaccines.

By using immunoblotting, neutralization, and ELISA, the development of secretory antibody responses to poliovirus type 3 virion proteins (VP1, VP2, VP3) and to intact or trypsin-treated poliovirus type 3 was studied in the nasopharyngeal secretions in groups of infants after immunization with live attenuated poliovirus vaccine (OPV), enhanced potency inactivated poliovirus vaccine (IPV-EP), or after combined vaccination with IPV-EP followed by OPV. After three doses of vaccine, infants in all vaccine groups developed similar secretory IgA response to VP1 and VP2. The antibody response to VP3 was observed in 76.5% of subjects immunized with OPV alone and approximately 60% of those immunized with IPV-EP followed by OPV. However, only 13% of those immunized with IPV-EP alone exhibited VP3-specific antibody response. Significant differences in poliovirus type 3 specific antibody activity were observed between OPV and IPV-EP immunized subjects when trypsin-treated poliovirus was used as the antigen for neutralization or for ELISA in vitro. The neutralizing antibody activity against cleaved virus was significantly higher than against whole virus in the OPV vaccinated subjects. Both neutralizing and ELISA antibody activity against cleaved virus was significantly lower than against the whole virus in IPV-EP immunized subjects.