Expression and immunogenicity of pertussis toxin S1 subunit-tetanus toxin fragment C fusions in Salmonella typhi vaccine strain CVD 908 - Barry,EM; GomezDuarte,O; Chatfield,S; Rappuoli,R; Pizza,M; Losonsky,G; Galen,J; Levine,MM (INFECTION AND IMMUNITY, 1996)