title: Status of paratyphoid fever vaccine research and development.
abstract: Salmonella enterica serovars Typhi and Paratyphi (S. Paratyphi) A and B cause enteric fever in humans. Of the paratyphoid group, S. Paratyphi A is the most common serovar. In 2000, there were an estimated 5.4 million cases of S. Paratyphi A worldwide. More recently paratyphoid fever has accounted for an increasing fraction of all cases of enteric fever. Although vaccines for typhoid fever have been developed and in use for decades, vaccines for paratyphoid fever have not yet been licensed. Several S. Paratyphi A vaccines, however, are in development and based on either whole cell live-attenuated strains or repeating units of the lipopolysaccharide O-antigen (O:2) conjugated to different protein carriers. An O-specific polysaccharide (O:2) of S. Paratyphi A conjugated to tetanus toxoid (O:2-TT), for example, has been determined to be safe and immunogenic after one dose in Phase I and Phase II trials. Two other conjugated vaccine candidates linked to diphtheria toxin and a live-attenuated oral vaccine candidate are currently in preclinical development. As promising vaccine candidates are advanced along the development pipeline, an adequate supply of vaccines will need to be ensured to meet growing demand, particularly in the most affected countries.
authors.affiliation: GSK Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy.
authors.forename: Laura B
authors.initials: LB
authors.lastname: Martin
authors.affiliation: Center for Vaccine Development and Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Raphael
authors.initials: R
authors.lastname: Simon
authors.affiliation: Jenner Institute, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom; Wellcome Trust Sanger Institute, Wellcome Trust Genomes Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom.
authors.forename: Calman A
authors.initials: CA
authors.lastname: MacLennan
authors.affiliation: Center for Vaccine Development and Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Tennant
authors.affiliation: International Vaccine Institute, Seoul, Republic of Korea.
authors.forename: Sushant
authors.initials: S
authors.lastname: Sahastrabuddhe
authors.affiliation: Center of Excellence for Women and Child Health, The Aga Khan University, Stadium Road, Karachi 74800, Pakistan. Electronic address: khan.m.imran@outlook.com.
authors.forename: M Imran
authors.initials: MI
authors.lastname: Khan
mesh_terms: D035843:Biomedical Research / Q000639:trends; D002986:Clinical Trials as Topic; D006801:Humans; D019081:O Antigens; D010284:Paratyphoid Fever / Q000517:prevention & control*; D012482:Salmonella paratyphi A; D012485:Salmonella typhi; D014435:Typhoid Fever / Q000517:prevention & control*; D014436:Typhoid-Paratyphoid Vaccines / Q000627:therapeutic use*; D014613:Vaccines, Attenuated / Q000627:therapeutic use; D018074:Vaccines, Conjugate / Q000627:therapeutic use
chemical_list: D019081:O Antigens; D014436:Typhoid-Paratyphoid Vaccines; D014613:Vaccines, Attenuated; D018074:Vaccines, Conjugate
keywords: Developing countries; Enteric fever; Paratyphoid fever; Salmonella; Salmonella paratyphi; Salmonella paratyphi A; Vaccine development; Vaccine policy; Vaccines