Abstract
Binding of two neutralizing monoclonal antibodies (Nt-mAbs) to natural empty capsids (NEC) of poliovirus, type 1, was blocked to the extent of 83 per cent to 98 per cent by monospecific rabbit antisera directed against the structural polypeptides VP1 and VP2. Monospecific antisera against VP3 or VP4, however, did not show this blocking effect. It is therefore assumed that VP1 and VP2 are located close together at the antigenic sites for the two mAbs.