EVALUATION OF RECOMBINANT RUBELLA-LIKE PARTICLES IN A COMMERCIAL IMMUNOASSAY FOR THE DETECTION OF ANTI-RUBELLA IGG

Background: We have investigated the performance of the novel rubella serology assay, Cobas(R) Core Rubella IgG EIA recomb, which uses rubel la-like particles (RLPs) expressed in transfected BHK-21 cells as the antigen. Study design: Evaluation of the assay included comparison wit h the hemagglutination inhibition (HAI) assay and another enzyme immun oassay (EIA) using native rubella virus (RV) as antigen, i.e. the Abbo tt IM(R)x Rubella IgG. The assay was calibrated against the WHO 1000 I U/ml reference serum and showed good correlation with the HAI test in the analysis of 404 serum samples. However, quantitative differences i n IgG values measured in the Cobas Core and the Abbott IMx assays were noted. Results: Values obtained for patient sera as well as CDC and W HO standards were generally more than twice as high in the Abbott IMx assay as in the Cobas Core test. Conclusions: For sera whose IgG level s in the immunoassay and HAI test were discordant, immunoblotting prov ed valuable as a confirmatory method and indicated that a significant number of HAI-negative samples were correctly interpreted as positive by the immunoassay.