An ELISA for the estimation of high-avidity and total specific IgG and IgM antibodies to rubella virus

High-avidity and total specific IgG and IgM antibodies to rubella virus were measured by using a curve-fitting analysis for the dose-response curves of enzyme-linked immunosorbent assay (ELISA). The analysis of follow-up samples from 14 patients with primary rubella infection revealed that these two antibody categories had different kinetics during the time after rash. The high-avidity IgG antibodies increased more slowly than total specific IgG antibodies. In the IgM response, high-avidity antibodies reached their maximum slightly earlier than total specific antibodies. After reinfection with rubella, 14-30 days after the illness, convalescent patients had higher amounts of high-avidity IgG antibodies when compared to the patients who suffered from primary rubella infection. These findings are in agreement with the results obtained by measuring antibody affinity in experimental animals after immunization.