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 Core Rubella IgG EIA recomb, which uses rubella-like particles (RLPs) expressed in transfected BHK-21 cells as the antigen.


METHODS
Evaluation of the assay included comparison with the hemagglutination inhibition (HAI) assay and another enzyme immunoassay (EIA) using native rubella virus (RV) as antigen, i.e. the Abbott IMx Rubella IgG. The assay was calibrated against the WHO 1000 IU/ml reference serum and showed good correlation with the HAI test in the analysis of 404 serum samples. However, quantitative differences in 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 WHO standards were generally more than twice as high in the Abbott IMx assay as in the Cobas Core test.


CONCLUSIONS
For sera whose IgG levels in the immunoassay and HAI test were discordant, immunoblotting proved valuable as a confirmatory method and indicated that a significant number of HAI-negative samples were correctly interpreted as positive by the immunoassay.
Pustowoit
B
B
Institute of Medical Microbiology, University of Leipzig, Liebigstrasse 24, D-04103 Leipzig, Germany.
Grangeot-Keros
L
L
Hobman
T C
TC
Hofmann
J
J