Physical identification of a virus in a crude leaf extract by its Ferguson plot in agarose gel electrophoresis

Crude extracts of turnip crinkle virus upon agarose gel electrophoresis yield (i) virus patterns unperturbed by contaminants; (ii) plots of mobility vs. gel concentration (Ferguson plots) parallel with those of the purified virus. The parallelism suggests similarity in size and shape but a lower net charge for the crude virus. This result is obtained when gel electrophoresis is carried out either in a continuous buffer or in a discontinuous (moving boundary electrophoresis) buffer system. The latter mode has the substantial benefit of electrophoretic (auto-)concentration of dilute virus sample prior to resolution. Thus, the Ferguson plot analysis in a discontinuous buffer system of turnip crinkle virus can be viewed as a model procedure for the physical identification of other viruses contained in dilute extracts, feasible even in the absence of a prior knowledge as to the nature of, or isolation of, the virus.