Electron Microscopy of the RNA of Foot-and-Mouth Disease Virus

Electron microscopic examination of molecules of single-stranded RNA requires their visualization as isolated and elongated strands. Inter- or intramolecular hydrogen bonding, which presumably is responsible for aggregation and tangling of single-stranded RNA, can be broken by the use of urea (Granboulan, Huppert & Lacour, 1966). Furthermore, incubation of purified reovirus with urea before spreading has been demonstrated as a gentle procedure for the release of double-stranded RNA (Granboulan & Niveleau, 1967; Vasquez & Kleinschmidt, 1968).

We describe here morphological studies on the RNA of foot-and-mouth disease virus. The method employed was the microdiffusion technique recently developed by Mayor & Jordan (1968) from the protein monolayer method of Kleinschmidt & Zahn (1959). A droplet of the virus suspension was mixed with a droplet of a 4 to 10 M-urea solution on an iced sheet of Teflon or dental wax.

^* Presented in part at the International Pilot Conference on Foot-and-Mouth Disease, Gustav Stern Foundation, New York, 25 and 26 May 1969, and at the 32. Tagung der Deutschen Gesellschaft für Hygiene und Mikrobiologie, Münster, 28. Mai 1969.