Search

A simple, sensitive, rapid method based on the principle of immunoadherence hemagglutination (IAHA) has been devised for the detection of rabies antibody. In this test, fixation of complement to complexes of rabies antigen with specific antibodies is readily detected by agglutination of human erythrocytes bearing receptors for C3. Sera from individuals undergoing preexposure rabies immunization were tested for rabies antibodies by the IAHA method and by a virus neutralization test performed in tissue culture, the rapid fluorescent focus inhibition test. IAHA titers showed a high degree of correlation with rapid fluorescent focus inhibition test titers, although it is not known whether results of the IAHA test represent the detection of neutralizing antibodies. An advantage of the IAHA test over the rapid fluorescent focus inhibition test was that results were obtained in a shorter period of time. In some instances, this can be of clinical significance in determining antibody levels to rabies virus. Furthermore, the IAHA test is most applicable as a rapid screening tool for the detection and quantitation of rabies antibodies in vaccinated subjects.

Approximately 7% of the sera tested to determine the presence of rubella-specific antibodies by the hemagglutination inhibition test demonstrated abnormal patterns of reactivity, rendering the test unreadable. Another 3% of sera were shown to have false-positive titers as high as 1:128. When these abnormally reacting and false-positive sera were heated at 56 degrees C for 30 min after chemical treatment they always converted to negative, indicating the absence of specific rubella hemagglutination-inhibiting antibody. These results were confirmed by fractionation of the sera after sucrose gradient centrifugation. It was established that manifestation of these nonspecific results was dependent on the concentration of Ca2+ or Mn2+. The heat-labile inhibitor(s) responsible for abnormal and false-positive reactions was found not to be complement. This inhibitor(s) was detected in the light fractions of sera and when added to negative sera was capable of reproducing the abnormal patterns of reactivity. These results emphasize the necessity of heating sera for the rubella hemagglutination inhibition test after the chemical removal of nonspecific inhibitors.