The application of a single radial haemolysis technique to foot-and-mouth disease virus-antibody study.

Experiments are described for the evaluation of the single radial haemolysis (SRH) technique applied to FMD virus, using a method involving the coupling of either antigen or antibody to sheep erythrocytes. The antigen coupling method detected specific antibody but the technique was found to be impractical as it gave reproducible results only with purified virions. However, the antibody coupling technique gave clear zones of lysis using tissue culture harvest virus as well as purified virus, and was also shown to be type specific for detecting antigen. A comparison of the SRH test with the single radial immunodiffusion (SRID) and complement fixation (CF) tests indicated that the SRH was a more sensitive test for assaying FMD antigen than either the SRID or CF tests. Although the SRH and SRID test results correlated well, those obtained in the SRH and CF tests did not. The test was not found to be superior to the CF test in assessing the quality of antigen since, like the CF test, it reacted both with the immunizing 140S antigen and the non-immunogenic 12S protein subunits.