Electrophoretic mobility and enhanced infectivity of a mutant of cowpea mosaic virus

Abstract

Four zones were partially resolved when cowpea mosaic virus was analyzed by polyacrylamide gel electrophoresis in a discontinuous pH system of unusual design. The four zones, in order of increasing mobility, were related to previously reported slow and fast migrating electrophoretic forms and to the top, middle, and bottom centrifugal components as follows: top component slow form, a mixture of middle plus bottom components slow form, top component fast form, and a mixture of middle plus bottom components fast form. The slow and fast electrophoretic forms were separated on a preparative scale by fractional precipitation. A mutant was isolated which was more infectious than the cowpea mosaic virus from which it was derived and which was converted more rapidly from slow to fast electrophoretic form in infected cowpeas. Both these properties seem to be controlled by the bottom component. The possible relationship of the conversion of the electrophoretic forms to the location of the capsid protein structural genes is discussed.