Use of a new buffer system with formalinized sheep erythrocytes in the rubella hemagglutination-inhibition test

An inhibitor to rubella hemagglutination present in bovine albumin preparations: its removal by treatment with kaolin

Certain commercial preparations of bovine albumin, fraction V, show inhibitory activity in the rubella hemagglutination (HA) and hemagglutination-inhibition (HI) tests. This does not appear to be due to albumin per se, but instead to a contaminant (or contaminants) with the properties of a lipoprotein. All inhibitory activity can be removed from albumin preparations by treatment with kaolin, gel filtration, or flotation ultracentrifugation. We have found that, even when there was no inhibition of HA titers, kaolin treatment of the albumins prior to their incorporation into the test diluent resulted in more clearly defined agglutination patterns. Reasons for and against including albumin in the test diluent are discussed. It is concluded that, although not essential, it is a worthwhile additive. Our data suggest, however, that each batch of albumin used for this purpose should be checked for the presence of inhibitor, and that treatment with kaolin might be considered as a routine step prior to its incorporation into the test diluent.

Cell-mediated immune response following natural rubella and rubella vaccination

Cell-mediated immunity (CMI), determined by estimating the production of MIF from sensitized leucocytes, was followed for 12 months after natural rubella infection (twenty-two subjects) and after vaccination with the Cendehill strain of attenuated rubella virus vaccine (forty subjects). Results were compared and correlated with the development of rubella haemagglutination inhibition antibody. The cell-mediated immune response commenced 1 week before the humoral immune response, but both responses reached a maximum simultaneously whether induced by natural infection or by vaccination. However, the CMI following natural rubella infection was of greater magnitude and duration than that stimulated by the vaccine virus. Twelve months after the initial stimulus, CMI could not be detected in any of the vaccinees, but was still present in some individuals after natural infection. This ability of the Cendehill vaccine virus to stimulate only shortlived, detectable CMI may be an important factor in the high reinfection rate observed following rubella vaccination.

Differential immune response to attenuated rubella virus vaccine

Serum samples collected from 18 volunteers 1, 2, and 3 months after vaccination with Cendehill strain of attenuated rubella virus vaccine were fractionated on a Sephadex G-200 column to test for immunoglobulin M (IgM) antibody. Seventeen of the 18 had demonstrable IgM antibody in serum collected 1 month postvaccination whereas only 5 and 3 had IgM antibody 2 and 3 months, respectively, post-inoculation. The geometric mean titers of hemagglutination-inhibiting antibody in the 19S fraction were 38, 7, and 6 at 1, 2, and 3 months after vaccination, whereas the corresponding 7S titers were 29, 53, and 57, respectively. Four other seronegative volunteers vaccinated with Cendevax were tested serially for total antibody only in whole blood obtained by finger pricks. Three of them showed appearance of antibody between 14 and 17 days and one between 17 and 21 days. It appears that vaccine-induced immune response is similar to natural infection especially with regard to the time of appearance of antibody and the relative proportions of IgM and IgG antibody thus produced.

Determination of rubella hemagglutination-inhibiting antibody in whole blood

A technique is described for determination of rubella hemagglutination-inhibiting antibody in only 50 to 100 muliters of whole blood.

Single-sample diagnosis of recent rubella by fractionation of antibody on Sephadex G-200 column

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.