Clinical validation of an antibody-capture anti-rubella IgM-ELISA.

An antibody-capture IgM-ELISA using monoclonal antibodies for conjugate was subjected to clinical validation with respect to sensitivity and specificity. In 103 serum specimens, known to contain anti-rubella IgM by a sucrose density gradient method, IgM was found by the ELISA in 99 sera. In a second study, 16 out of 17 acute rubella infections were detected by the IgM-ELISA. In 17 out of 17 vaccinees, a specific IgM response could be demonstrated. Specificity of the antibody-capture ELISA was found to be high; no interference was seen in 60 rheumatoid-factor positive sera, in 100 highly positive IgG sera or 10 sera with anti-CMV IgM. Only one out of 100 sera with heterophile antibodies showed a positive response. In acute rubella infections, IgM was shown to be detectable from 1 to 4 days after onset of illness up to about 12 wk, with peak values at about 1 wk after onset.