Loss of virulence by heterophil-adapted Salmonella pullorum.
We report that reduction of virulence for day-old chicks was achieved after eight-times-repeated heterophil passage of Salmonella pullorum (SP). The virulent source strain SP-V caused 64% mortality and 89% internal organ as well as 89% cecal colonization 10 days after administration of 10(7) colony-forming units (CFU) to day-old chicks. Eight-times-repeated passage of SP in heterophils resulted in attenuated strain SP-A that was nonlethal and reduced colonization of internal organs from 89% for SP-V strain to 4.3% for SP-A strain 10 days after administration of 10(7) or 10(8) CFU to day-old chicks. Cecal colonization was reduced from 89% for SP-V strain to 0 for SP-A strain 10 days after administration of 10(7) or 10(8) CFU to day-old chicks.
Kramer
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Veterinary Medical Research Institute, College of Veterinary Medicine, Iowa State University, Ames 50011, USA.
Hirl
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D000818:Animals; D002060:Bursa of Fabricius / Q000382:microbiology; D002432:Cecum / Q000382:microbiology; D002645:Chickens; D015169:Colony Count, Microbial / Q000662:veterinary; D006098:Granulocytes / Q000276:immunology / Q000382:microbiology; D008099:Liver / Q000382:microbiology; D010587:Phagocytosis; D011201:Poultry Diseases / Q000382:microbiology* / Q000401:mortality / Q000503:physiopathology; D012475:Salmonella / Q000276:immunology / Q000302:isolation & purification / Q000472:pathogenicity*; D012481:Salmonella Infections, Animal / Q000382:microbiology* / Q000401:mortality / Q000503:physiopathology; D012692:Serial Passage; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000382:microbiology; D013997:Time Factors; D014774:Virulence