A live oral fowl typhoid vaccine with reversible o-antigen production

Arindam Mitra, Paweł Łaniewski, Roy Curtiss, Kenneth L. Roland

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Salmonella enterica serovar Gallinarum causes fowl typhoid, recognized worldwide as an economically important disease. The current vaccine, 9R, lacks a complete O antigen, which is a Salmonella virulence factor, and, in addition, has a number of other less well characterized chromosomal mutations. For optimal efficacy, 9R is administered by injection. In an effort to develop a vaccine suitable for oral administration, we constructed Salmonella Gallinarum strains with a reversible O-antigen phenotype. In this scenario, the vaccine strain produces full-length O antigen at the time it is administered to birds. After the vaccine has had time to colonize internal lymphoid tissues, the O-antigen is gradually lost, resulting in an attenuated strain. We found that strains carrying single mutations conferring this phenotype, δpmi and arabinose-regulated rfc, retained virulence. However, a mutant strain carrying both of these mutations was completely attenuated and immunogenic in chickens. This work demonstrates a novel approach for developing live Salmonella vaccines for poultry.

Original languageEnglish (US)
Pages (from-to)52-56
Number of pages5
JournalAvian diseases
Issue number1
StatePublished - Mar 1 2015


  • Salmonella Gallinarum
  • chicken
  • fowl typhoid
  • live attenuated vaccine
  • regulated O-antigen synthesis

ASJC Scopus subject areas

  • Food Animals
  • Animal Science and Zoology
  • General Immunology and Microbiology


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