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Four-day-old chickens infected orally with a spectinomycin-resistant (Spcr) mutant of a highly invasive avian Salmonella typhimurium strain excreted salmonellae in the feces for at least 10 weeks. When these chickens were reinfected at this time with a nalidixic acid-resistant (Nalr) mutant of the same strain, they excreted this mutant in significantly(More)
An indirect ELISA has been developed to detect Salmonella typhimurium antibodies in chicken sera, using whole bacterial cell protein, flagellar protein or lipopolysaccharide as antigens. In experimental infections high concentrations of S typhimurium-specific IgG persisted after the faecal excretion of S typhimurium had ceased, whereas the specific IgM(More)
We have constructed and evaluated a live avirulent Salmonella typhimurium vaccine strain, attenuated by deletion (delta) mutations in genes for adenylate cyclase (cya) and the cAMP receptor protein (crp). Immunization of chicks can preclude Salmonella colonization and invasion of challenged vaccinated chickens when compared with the non vaccinated control.(More)
Chickens given orally at 4 days of age a smooth spectinomycin resistant mutant (Spcr) of Salmonella typhimurium strain F98 excreted the organism in their faeces for approximately 4 weeks. Following oral administration of a nalidixic acid resistant (Nalr) mutant of the same strain 4 weeks later when the chickens had virtually cleared themselves of the first(More)
The effect of experimental Salmonella infection on chicken lymphoid organs, immune responses, and fecal shedding of salmonellae were assessed following oral inoculation of 1-day-old chicks or intra-air-sac infection of 4-week-old chickens with virulent S. typhimurium wild-type chi 3761 or avirulent S. typhimurium delta cya delta crp vaccine strain chi 3985.(More)
The influence of infective dose on chicken immunogenicity was examined in 1-week-old chickens. Chickens were infected orally with various doses of chi 3761 or chi 3985. Fecal shedding, colonization of the cecum, and induction of Salmonella-specific serum immunoglobulin isotypes were analyzed over a 5-week period. The delta cya delta crp Salmonella(More)
Infection of animals and humans with Salmonella is a consequence of oral consumption of food or fluids contaminated with Salmonella. Once in the intestine, Salmonella usually attach to, invade, and proliferate in enterocytes or the cells of the gut associated lymphoid tissue (GALT). The latter route of infection can lead to disease or to an asymptomatic(More)
Oral immunization with a delta cya delta crp Salmonella typhimurium strain has been shown to preclude colonization by wild-type, virulent S. typhimurium and induces humoral and cellular immune response in chickens. Intestinal tract colonization by the virulent challenge strain was used to determine the level of protection conferred by immunization with the(More)