Quantitation of D antigen content in inactivated poliovirus vaccine derived from wild-type or sabin strains.

ABSTRACT

The enzyme-linked immunosorbent assay (ELISA) is currently the in vitro method for the measurement of the D antigen content of inactivated poliovirus vaccines (IPV) of greatest interest. The sensitivity and specificity of the test is dependent on the antibodies selected for use. We evaluated monoclonal and polyclonal antibodies for specificity to D antigen and wild or attenuated (Sabin) strains used in vaccine production. When used as detection antibodies the types 1 and 2 monoclonal antibodies raised against wild-type poliovirus strains were D antigen-specific and cross-reactive with the corresponding Sabin strains. The type 3 monoclonal antibody was weakly cross-reactive with Sabin type 3 vaccine. In contrast, polyclonal antibodies were less D antigen-specific, but reacted equally well with wild-type and Sabin strain vaccines. The ELISA using monoclonal antibodies was shown to be highly reproducible. Reactivity with these monoclonal antibodies implies that a D-specific neutralizing epitope of each respective poliovirus type has been preserved in the inactivation process. Evaluation with additional neutralizing D antigen-specific monoclonal antibodies may be necessary to determine whether reactivity with one epitope of each type in an in vitro test is sufficient to predict potency of the vaccine in humans.