The BC loop in poliovirus coat protein VP1: an ideal acceptor site for major insertions.

In poliovirus the BC loop of the VP1 coat protein is hypervariable and can accommodate numerous foreign sequences introduced by genetic engineering. This paper examines the characteristics of the VP1 BC loop of the picornaviruses to see why this loop is so variable and particularly favourable for the insertion of foreign sequences leading to the formation of chimeric particles. The characteristics which make this loop distinctive can be used to find equally permissive loops in other proteins.