D-antigen determination in polio vaccine production: comparison of gel diffusion and ELISA methods.

Up to now gel diffusion is widely used for in vitro determination of polio D-antigen. This method has several disadvantages, its relatively low sensitivity being the main one. Generally samples have to be concentrated, which requires fairly large amounts of material and often results in some loss of antigen due to adsorption. Two ELISA methods have been developed for determination of polio D-antigen. These tests have a high sensitivity, approximately 1 DU/ml, and require very small amounts of sample and antisera. Using the indirect method only one HRPO conjugated antiserum is needed for quantitation of type 1, 2 and 3 D-antigen. Comparison of D-antigen values obtained by ELISA and gel diffusion for a number of vaccines revealed a good correlation between the different methods. The indirect ELISA method has also been applied successfully for D-antigen quantitation of A1PO4 adsorbed DT-and DPT-polio vaccines.