Typical example of an SDS-PAGE gel comparing 10 different strains of FMD virus serotype A. Semi-purified virus preparations are run from top to bottom by electrophoresis, and labelled bands represent polypeptides of decreasing molecular weight towards the bottom. The position of the three structural (capsid) proteins, VP1, 2 and 3 are indicated. Other visible bands represent non-specific or indeterminate components.