[Serological study of several strains of foot-and-mouth disease virus type "O" isolated in Europe between 1971 and 1975: application of the biomathematical system of classification].

Nine strains of foot-and-mouth disease virus type "O" received in our laboratories since 1971 have been studied serologically by Osler's quantitative method of complement fixation (50% hemolysis). The results, submitted to the biomathematical system of bidimensional classification, allow to conclude that at present in Europe there are two groups of foot-and-mouth disease strains of type "O"; one has reference to our vaccinal strain "O Lausanne 1965" and the other to "O Romania 1972" strain, which has certain points of similarity with subtype "O2". In addition, strain "O Hungary 1975" has been studied on bovines; the immunological tests confirm the serological test.