Rapid quantitative assay of rabies post-vaccination antibody by ELISA

An improved method of ELISA for rabies post-vaccination antibody determination has been developed comparing adsorption properties of polystyrene beads and microtitre plates which were coated with different concentrations of rabies virus antigen. All 106 human post-vaccination serum samples tested were found repeatedly positive within the range of mean values (MV) from 1.4 to 43.0 international units (IU)/0.1 ml. The plates displayed much higher coefficient of variation (CV) when testing lower serum dilutions in different wells of the same plate. In higher dilutions, the sera with high and low antibody levels could easily be distinguished, the results corresponding well to those of the indirect fluorescent antibody test (IFAT), with the exception of some negative sera also to those obtained by ELISA at the Institut Pasteur (Paris). The slightest CV occurred with a 1:400 serum dilution on beads, indicating that ELISA using beads as solid phase can be recommended as a rapid, sensitive and reliable technique for quantitative assay of rabies post-vaccination antibody.