The genome of FMDV is not DNA, but RNA. Using molecular biology, one can copy the entire FMDV RNA genome back into DNA. This means many more techniques can be brought to bear in the study and manipulation of the FMDV genome. The FMDV ‘replicon’ is a form of the DNA copy in which there is a large deletion within the region of the genome which encodes the proteins which make up the particle (the ‘shell’) of the virus.
This form of genome is able to copy itself (‘replicate’), but absolutely cannot make infectious particles. The modified genome cannot transmit itself from one cell to another, let alone infect an animal and cause disease. We are able to use this ‘replicon’ form of the genome to study how the virus grows within a cell in a completely biosecure manner. By law, infectious FMDV can only be studied in laboratories licensed by Government.