Comparison of haemagglutination test, enzyme-linked immunosorbent assay and indirect immunofluorescence antibody test for determination of rubella immune status

Comparative evaluations of immune status for rubella are described for the enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence (IFA) and two standard haemagglutination inhibition tests (HAI kaolin; HAI heparin-MnCl2). In general, a reasonably good correlation was obtained between the level of rubella antibodies measured by the HAI (kaolin) test and by ELISA, but an appreciable proportion (15%) of ELISA positive specimens were encountered among HAI (kaolin) negative sera. All of these HAI negative, ELISA positive sera, except one were found to be positive for rubella antibodies by IFA. Neutralization test performed on this serum positive by ELISA only, confirmed the presence of protective rubella antibodies. Of all the tests evaluated ELISA appeared unequivocally to be the most sensitive test followed closely by IFA. The standard HAI (heparin-MnCl2) was more suitable than the HAI (kaolin), for the determination of immune status. Further, no linear relationship between single rubella virus HAI and ELISA values was observed.