Examination of differences between foot-and-mouth disease virus strains using a radioimmunoassay techinque

A radioimmunoassay (RIA) technique was used to compare different samples of type SAT 2 foot-and-mouth disease (FMD) viruses. The reaction involved the measurement of the competition of heterologous virus with homologous virus for previously titrated homologous antiserum. The results showed that differences occurred between the viruses examined. Viruses could be grouped according to their ability to compete with the homologous virus, and statistically significant differences between virus 'groups' were observed. A comparison of the relationships between the viruses using RIA and complement fixation tests was made. The results did not always correlate. Certain homologous antigen/antibody combinations were more discriminating. The method might prove useful in the examination of a large number of field strain viruses using a well-characterized vaccine virus homologous system, particularly if the method is adapted to use antisera specific for the neutralizing antigen of the homologous test virus.