Purification and Electron Microscopy of Foot-and-Mouth Disease Virus

Summary

Foot-and-mouth disease virus (FMDV), type A, from bovine-kidney tissue cultures has been purified successively by methanol precipitation, extraction with organic solvents, and differential centrifugation. The FMDV particle in the resulting purified virus concentrates has been identified by analytical electron microscopy in air-dried specimens as a uniform-sized 22-mμ particle. This identification was made through correlative experiments relating particle counts to infectivity and to aggregation of the particles with antiviral bovine serum. While an average of 690 virus particles was present in one plaque-forming unit for bovine-kidney monolayer cultures, a value as low as 33 was obtained.