Picornaviruses encode different proteases depending on the virus species although it is common to all of them to encode 3C pro and its precursor 3CD pro (Figure 2 ). In PV, both these exhibit protease activity, and they execute most of the hydrolytic events on the viral polyprotein [2, 23, 40] . Apart from these two proteases, 3C pro and 3CD pro , picornaviruses also contain a 2A gene, whose product in some species exhibits proteolytic activity, as is the case for PV ( Figure 2) . 2A pro has a limited proteolytic effect on the polyprotein and its function is most probably one of altering cellular functions by the cleavage of a number of cellular proteins. In this regard, the best studied of these cleavages is the bisection of eIF4G ( Figure 3 ) [14] .