Killed but metabolically active Salmonella typhimurium: application of a new technology to an old vector.
Previous studies have shown that attenuated salmonellae utilized as vaccine vectors engender strong immune responses; however, balancing immunogenicity with reactogenicity remains problematic. Recent work in other bacteria has shown that photochemical treatment of DNA excision repair mutants ( Delta uvrAB) renders organisms "killed but metabolically active" (KBMA). Here, we extend this concept to Salmonella typhimurium. A strain of attenuated S. typhimurium previously evaluated in human volunteers was further deleted for uvrAB genes and designated CKS362. Photochemical treatment of CKS362 resulted in significant inactivation. These KBMA organisms were metabolically active as shown by radioactive methionine incorporation and lactate dehydrogenase activity. In mice inoculated intraperitoneally, KBMA CKS362 was markedly less reactogenic and stimulated a humoral immune equivalent to its live counterpart. Because the parental strain has previously been found to elicit strong immune responses to Salmonella antigens, we propose CKS362 as a prototype strain to test the immunogenicity of KBMA organisms in humans.
Lankowski
Alexander J
AJ
Infectious Diseases Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Hohmann
Elizabeth L
EL
D000818:Animals; D000942:Antigens, Bacterial / Q000378:metabolism; D001426:Bacterial Proteins / Q000032:analysis / Q000096:biosynthesis; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D012480:Salmonella Infections / Q000276:immunology*; D022562:Salmonella Vaccines; D012486:Salmonella typhimurium / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000472:pathogenicity; D013154:Spleen / Q000502:physiology; D013460:Sulfur Isotopes / Q000032:analysis; D014466:Ultraviolet Rays; D015164:Vaccines, Inactivated; D014774:Virulence
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D022562:Salmonella Vaccines; D013460:Sulfur Isotopes; D015164:Vaccines, Inactivated