Use of short analytical ultracentrifugation runs for the isopycnic determination of foot-and-mouth disease virus concentration and density in autoformed caesium chloride gradients.

Short analytical ultracentrifugation runs of less than six hours with autoformed CsCl density gradients were used for routine FMDV density and concentration analysis. The values obtained after short runs were slightly higher for concentration and lower for density than after classical 22 h runs. These differences between the 6 and the 22 h values were related to virus strain and did not seem to result of the incomplete stabilisation of the CsCl gradient, but of the shorter virion/CsCl contact period.