Isoelectric focusing of viral polypeptides in urea. A methodological study on poliovirus.

The applicability of isoelectric focusing in urea to the analysis of viral polypeptides is reported, using poliovirus as a model. Experimental techniques for the dissociation of virus particles, for isoelectric focusing in urea-containing polyacrylamide gels (rods, flat bed and slab gels) and for pH measurement and two-dimensional analysis are described and their results, as applied to poliovirus polypeptides, discussed. Special attention is given to problems of recovery of all of the proteins and the incidence of artifacts. The influence of reagents, dissociation conditions, focusing procedures and preparation and storage of virus material on the occurrence of charge modifications of the polypeptides has been investigated. Some recommendations are made for the application of the method to other viruses of particles.