Antibody response in rubella reinfection

Determination of rubella immunity by latex agglutination: its place in clinical routines

The sensitivity and specificity of Rubascan (r) (RSC), a new latex agglutination test for rubella antibodies, was compared with those of the single radial hemolysis (SRH) and hemagglutination inhibition (HI) tests. We found RSC to have a sensitivity versus SRH and HI of 90-95% and 70-72%, respectively. RSC had a specificity versus SRH and HI of 97-100% and 96-100%, respectively. However, only 4/7 titer rises from cases of acute rubella or rubella vaccinations were clearly discernible in RSC. Moreover, only 2/10 anti-rubella IgG and IgM containing sera were RSC positive after protein A absorption although 10/10 were still HI positive. Additionally, the HI-positive IgM fractions from a sucrose density gradient centrifugation of an anti-rubella IgM containing serum were negative. We conclude that IgM reacts differently from IgG in RSC. We consider RSC a potentially useful reagent for determination of immunity in non-acute situations, and in non-pregnant persons like in pre-employment testing. This could be performed by relatively untrained personnel. On the other hand a rubella immunity test in pregnant women or in acute rubella should preferably be truly quantitative, in order to allow precise titer comparisons. In these cases, the interpretation of tests may require experience, and they should be performed at more specialized laboratories.

Congenital rubella after maternal reinfection

This report concerns a boy with congenital rubella virus infection. The diagnosis was confirmed by virus isolation, demonstration of rubella-specific serum IgM and by persistence of serum antibody at the age of 9 months. In 2 sera from the mother sampled 2 weeks apart 20 months before the birth of the boy, low titers of rubella antibody were demonstrated by hemagglutination-inhibition, hemolysis-in-gel and complement fixation tests, but not by neutralization. Significant rises in titer were demonstrable by all serologic reactions--including neutralization--at the time of birth of the infected child. The mother was not aware of any rubella-like illness or exposure to such disease during pregnancy. The case is discussed against findings of neutralizing activity in sera from natural immunes and rubella vaccinees.

In vitro effects of rubella virus, strain RA 27/3, on human lymphocytes. I. Viral inhibition of mitogen stimulation in relation to Rubella Haemagglutination inhibition antibodies

The inhibiting effect of rubella virus on lymphocyte stimulation in vitro was studied, using purified virus of the attenuated strain RA 27/3. Addition of the virus to human lymphocytes from twenty healthy blood donors before stimulation with leuco-agglutinin (LA), a component of phytohaemagglutinin, caused a considerable inhibition of the LA response in some experiments, whereas in other experiments the inhibition was slight or non-existent. If further analysed, the results showed a correlation between the degree of inhibition and the immunity of the lymphocyte donor against rubella, as measured by haemagglutination inhibition (HI). Thus the LA-response was significantly more depressed in a group of lymphocyte donors with HI-titres ranging from 20 to 160 than in another group with HI-titre less than 5. Possible explanations of the virus-induced inhibition of the LA response and possible connection between this phenomenon and the immune response against rubella are discussed.