title: Oral immunization with ATP-dependent protease-deficient mutants protects mice against subsequent oral challenge with virulent Salmonella enterica serovar typhimurium.
abstract: We evaluated the efficacy of mutants with a deletion of the stress response protease gene as candidates for live oral vaccine strains against Salmonella infection through infection studies with mice by using a Salmonella enterica serovar Typhimurium mutant with a disruption of the ClpXP or Lon protease. In vitro, the ClpXP protease regulates flagellum synthesis and the ClpXP-deficient mutant strain exhibits hyperflagellated bacterial cells (T. Tomoyasu et al., J. Bacteriol. 184:645-653, 2002). On the other hand, the Lon protease negatively regulates the efficacy of invading epithelial cells and the expression of invasion genes (A. Takaya et al., J. Bacteriol. 184:224-232, 2002). When 5-week-old BALB/c mice were orally administered 5 x 10(8) CFU of the ClpXP- or Lon-deficient strain, bacteria were detected with 10(3) to 10(4) CFU in the spleen, mesenteric lymph nodes, Peyer's patches, and cecum 1 week after inoculation and the bacteria then decreased gradually in each tissue. Significant increases of lipopolysaccharide-specific immunoglobulin G (IgG) and secretory IgA were detected at week 4 and maintained until at least week 12 after inoculation in serum and bile, respectively. Immunization with the ClpXP- or Lon-deficient strain protected mice against oral challenge with the serovar Typhimurium virulent strain. Both the challenged virulent and immunized avirulent salmonellae were completely cleared from the spleen, mesenteric lymph nodes, Peyer's patches, and even cecum 5 days after the challenge. These data indicate that Salmonella with a disruption of the ATP-dependent protease ClpXP or Lon can be useful in developing a live vaccine strain.
authors.affiliation: Laboratory of Immunoregulation, Department of Infection Control and Immunology, Kitasato Institute for Life Sciences, Kitasato University, Minato-ku, Tokyo 108-8641, Japan. hmatsui@lisci.kitasato-u.ac.jp
authors.forename: Hidenori
authors.initials: H
authors.lastname: Matsui
authors.forename: Masato
authors.initials: M
authors.lastname: Suzuki
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Isshiki
authors.forename: Chie
authors.initials: C
authors.lastname: Kodama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Eguchi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kikuchi
authors.forename: Kenji
authors.initials: K
authors.lastname: Motokawa
authors.forename: Akiko
authors.initials: A
authors.lastname: Takaya
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Tomoyasu
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000235:genetics; D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001646:Bile / Q000276:immunology; D015169:Colony Count, Microbial; D049071:Endopeptidase Clp; D005260:Female; D017353:Gene Deletion; D006360:Heat-Shock Proteins / Q000235:genetics*; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D012481:Salmonella Infections, Animal / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D022562:Salmonella Vaccines / Q000008:administration & dosage / Q000276:immunology*; D012486:Salmonella typhimurium / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D012697:Serine Endopeptidases / Q000235:genetics*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology*; D014774:Virulence
chemical_list: D000907:Antibodies, Bacterial; D006360:Heat-Shock Proteins; D022562:Salmonella Vaccines; D014613:Vaccines, Attenuated; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases