GENETICALLY DETOXIFIED DERIVATIVE OF HEAT-LABILE ESCHERICHIA-COLI ENTEROTOXIN INDUCES NEUTRALIZING ANTIBODIES AGAINST THE A-SUBUNIT - PIZZA,M; FONTANA,MR; GIULIANI,MM; DOMENIGHINI,M; MAGAGNOLI,C; GIANNELLI,V; NUCCI,D; HOL,W; MANETTI,R; RAPPUOLI,R (JOURNAL OF EXPERIMENTAL MEDICINE, 1994)