A 'triple gene block' (TGB), a specialized evolutionarily conserved
gene module involved in the cell-to-cell and long-distance movement
of viruses. The TGB-based transport system exploits the
co-ordinated action of three polypeptides to deliver viral genomes
to plasmodesmata and to accomplish virus entry into neighbouring
Expression of a modified TGB gene could protect transgenic plants
against a range of viruses possessing a TGB protein.