Tackling the issue of environmental survival of live Salmonella Typhimurium vaccines: deletion of the lon gene.
Vaccination is an important measure to control Salmonella contamination in the meat production chain. A previous study showed that both the ΔrfaJ and ΔrfaL strains are suitable markers and allow serological differentiation of infected and vaccinated animals. The aim of this study was to verify whether deletion of the lon gene in a Salmonella Typhimurium ΔrfaJ marker strain resulted in decreased environmental survival. Our results indicate that deletion of the lon gene in the ΔrfaJ strain did not affect invasiveness in IPEC-J2 cells and resulted in an increased susceptibility to UV, disinfectants (such as hydrogen peroxide and tosylchloramide sodium) and citric acid. Immunization of pigs with inactivated ΔrfaJ or ΔlonΔrfaJ vaccines allowed differentiation of infected and vaccinated pigs. Furthermore, deletion of the lon gene did not reduce the protection conferred by live wild type or ΔrfaJ vaccines against subsequent challenge with a virulent Salmonella Typhimurium strain in BALB/c mice. Based on our results in mice, we conclude that deletion of lon in ΔrfaJ contributes to environmental safety of the ΔrfaJ DIVA strain.
Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, University of Ghent, Salisburylaan 133, 9820 Merelbeke, Belgium. Bregje.leyman@ugent.be
Bregje
B
Leyman
Filip
F
Boyen
Alexander
A
Van Parys
Elin
E
Verbrugghe
Freddy
F
Haesebrouck
Frank
F
Pasmans
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001428:Bacterial Vaccines / Q000276:immunology*; D002432:Cecum / Q000382:microbiology; D002460:Cell Line; D004202:Disinfectants / Q000494:pharmacology; D004783:Environmental Microbiology; D015964:Gene Expression Regulation, Bacterial; D008099:Liver / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D012481:Salmonella Infections, Animal / Q000517:prevention & control*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics / Q000276:immunology* / Q000528:radiation effects; D013154:Spleen / Q000382:microbiology; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology / Q000517:prevention & control; D014466:Ultraviolet Rays
D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D004202:Disinfectants