title: Oral immunization with a dam mutant of Yersinia pseudotuberculosis protects against plague.
abstract: Inactivation of the gene encoding DNA adenine methylase (dam) has been shown to attenuate some pathogens such as Salmonella enterica serovar Typhimurium and is a lethal mutation in others such as Yersinia pseudotuberculosis strain YPIII. In this study the dam methylase gene in Yersinia pseudotuberculosis strain IP32953 was inactivated. Unlike the wild-type, DNA isolated from the mutant could be digested with MboI, which is consistent with an altered pattern of DNA methylation. The mutant was sensitive to bile salts but not to 2-aminopurine. The effect of dam inactivation on gene expression was examined using a DNA microarray. In BALB/c mice inoculated orally or intravenously with the dam mutant, the median lethal dose (MLD) was at least 10(6)-fold higher than the MLD of the wild-type. BALB/c mice inoculated with the mutant were protected against a subcutaneous challenge with 100 MLDs of Yersinia pestis strain GB and an intravenous challenge with 300 MLDs of Y. pseudotuberculosis IP32953.
authors.affiliation: Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Taylor
authors.affiliation: Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK.|Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Titball
authors.affiliation: Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK.
authors.forename: Petra C F
authors.initials: PCF
authors.lastname: Oyston
mesh_terms: D015075:2-Aminopurine / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D001647:Bile Acids and Salts / Q000494:pharmacology; D004269:DNA, Bacterial / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D020411:Oligonucleotide Array Sequence Analysis; D010930:Plague / Q000517:prevention & control*; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000235:genetics*; D016019:Survival Analysis; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014774:Virulence; D015010:Yersinia pestis / Q000276:immunology / Q000472:pathogenicity; D015011:Yersinia pseudotuberculosis / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity
chemical_list: D000900:Anti-Bacterial Agents; D001428:Bacterial Vaccines; D001647:Bile Acids and Salts; D004269:DNA, Bacterial; D014613:Vaccines, Attenuated; D015075:2-Aminopurine; C058693:Dam methyltransferase; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D015252:Deoxyribonucleases, Type II Site-Specific; C024405:GATC-specific type II deoxyribonucleases