Electron microscopy demonstration of fibrillar structures in the foot-and-mouth disease virus]

Purified FMD virus was heat treated and then examined by electron microscopy with the negative contrast technique. Fibrils of varying length and thickness were present; they were not present after ribonuclease treatment. They were similar to the fibrils described for other picornaviruses. Viral RNA was the essential component of these artificially arranged fibrils, which were composed of threads about 10 A wide, separated from one another by a gap of about 10 A.