Abstract
The RNA genome of rotaviruses consists of 11 segments in four size-classes which can be separated by polyacrylamide gel electrophoresis, although 11 separate bands are not shown by all strains. We propose a cryptogram (Rotacode) based on the relative distance of migration of adjacent bands in each size-class for coding the typical pattern of each strain of virus. This provides a shorthand for recording details of each strain and for grouping electrophoretically similar strains. Rotacode was found to be reliable and reproducible, with identical codes being obtained for the same samples in repeated experiments under code and by various observers. Rotacode was also used to analyse 189 strains obtained over a three-year period and differentiated 13 electrophoretypes. This confirms the considerable electrophoretic variability of wild strains.