[Radial immunodiffusion study of foot-and-mouth disease virus type A].

The radial immunodiffusion(RI), was used to study F. M. D. viruses, type A. It was found that the specific linkage between F. M. D. antigens and antibodies could be demonstrated through RI with the formation of precipitation circles. It was demonstrated that specific reactions were produced when homologus or heterologus antigens and sera of one and the same F. M. D. virus type interacted. The size of the precipitation circles proved inversely proportional to the concentration of antibodies in the homologous systems. It was also established that RI could be made use of in the demonstration of some subtype differences between the F. M. D. antigens of type A. Discussed is the problem of RI sensitivity as well as the possibility of using this technique for the early diagnosis of the F. M. D. infection and the study of the F. M. D. viruses.