In three cattle vaccination experiments, with three strains of the virus of foot-and-mouth disease, it was shown that virus passaged in culture in cattle tongue epithelial tissue was as effective an antigen as virus passaged in cattle.
With two virus strains, the virus content of the culture at the peak of infectivity was about the same as that of vesicle epithelium from the tongues of reacting cattle. Variable and less satisfactory results were obtained with the third strain, but one culture passage yielded tissue of sufficiently high virus content for the preparation of vaccine of adequate potency.
No modification in the antigenic behaviour of the strains was detected as a result of passage in culture.
It is a pleasure to acknowledge the technical assistance given by Mr W. J. Brownsea.