Completion of hemagglutination inhibition test by solid-phase radioimmunoassay test in routine diagnostic rubella serology.

A solid-phase radioimmunoassay (RIA) test for rubella virus IgG and IgM class antibodies was used for completing the hemagglutination inhibition (HI) test in routine diagnostic serology. During a six-month period 80 serum specimens from 47 patients were tested by RIA because the HI test result was either unreliable or gave insufficient information. This was approximately 5% of the total number of serum specimens tested for rubella antibodies in our laboratory during the study period. The main indications for using the RIA test were improper timing in the taking of serum specimens, which accounted for IgM determination, and nonspecific agglutinins or nonspecific serum hemaglutination inhibitors, which disturbed the HI test. In all cases an unambiguous result was obtained by the RIA test, and five recent rubella infections, not diagnosably by the HI test, were detected. Based on these findings we consider the RIA test to be a good alternative among the methods proposed for diagnostic rubella serology.