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)