[Diagnosis of rubella by demonstrating rubella-specific 19 S and 7 S antibodies (author's transl)].

Identification and measurement of rubella antibody of 19 S (IgM) and 7 S (IgG) immunoglobulins by sucrose density gradient centrifugation and a modified hemagglutination-inhibition (HAI)-test is described. Human group 0 of red blood cells were employed after trypsination. The method proved to be highly reliable and sensitive for the rapid detection of rubella IgM antibody in routine research to make an accurate diagnosis of recent rubella infection. Sera from 185 pregnant women, 200 children suspect of congenital infection, 15 mothers of intrauterin infected children, and 32 cases of rubella vaccine-induced immunity control were studied. In postnatal rubella infections, specific IgM-antibody could be detected in all sera after the onset of the rash up to eight or ten weeks after infection. From March 1973 until September 1974 laboratory diagnosis confirmed 30 of 185 pregnant women to have been recently infected with rubella. In less than 3% (4 cases) the results could not confirm or exclude a recent history of rubella. Among 200 children with congenital defects or some irregular development, specific IgM antibody was detected in 36 cases. The diagnosis of congenital rubella was confirmed or detected in the first months of life. One of the infected children was well at birth but later developed mental retardation and hearing loss, and some others showed only minor defects. In some children rubell IgM antibody persisted 5-14 months. IgM rubella antibody was not found in the sera of 15 mothers from children with intrauterine infection confirmed by IgM antibody demonstration. Post-vaccination-tests showed serum IgM and IgG immunoglobulin-responses to be similar to the natural rubella-virus-infection. Maximal titers of both immunoglobulin-fractions were but four-fold lower after vaccination (28 of 32 tested cases). The described method is able to verify the time of infection by testing a single serum. The HAI-test of the 12 fractions collected from each serum after density-gradient centrifugation shows a typical titer-profil for every time of immunization status: beginning with traces of IgM-antibody - when the HAI-test of the uncentrifugated serum may be less than 1:10 - until 10 weeks after infection when only IgG-antibody will be detectable. The greatest amount of IgM-antibody is found in the 2. to 4. week after the rash.