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.     

Host cell modulation of foot-and-mouth disease virus procapsid synthesis

BHK21 (clone 13S) cells of high (BHK-SH) and low (BHK-SL) passage number were infected with foot-and-mouth disease virus (FMDV) subtypes A24, A25 and C3. While the amount of virus specific RNA produced in BHK-SH cells was 25% of that in BHK-SL cells and the virion production was 27% (C3) to 53% (A24) lower, the synthesis of viral proteins was comparable, associated with an accumulation of procapsids in BHK-SH cells. The results suggest that changes in viral infection pattern with increasing BHK21 cell passage number should be considered in FMDV vaccine production.