Abstract

To facilitate the diagnosis of recent rubella infection, rubella haemagglutination inhibiting antibody has been determined in four fractions obtained by Sephadex G-200 gel filtration of samples of serum. All the 21 samples collected at the convalescent stage of the disease had varying proportions of haemagglutination inhibiting antibody in fraction 1, representing the major portion of IgM antibody whereas all but three out of 22 sera from persons with no history of recent rubella had negative titres in this fraction. The haemagglutination inhibiting titres in the three positive sera in the second group was very low as compared to the other fractions. Fractionation of sera on a Sephadex G-200 column coupled with the rubella haemagglutination inhibition test can, therefore, be used to diagnose recent rubella infection.