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.