Pathogenesis of Campylobacter fetus infections. Role of surface array proteins in virulence in a mouse model.
We developed a mouse model to compare the virulence of Campylobacter fetus strains with (S-plus) and without (S-minus) surface array protein (S-protein) capsules. In adult HA/ICR mice pretreated with ferric chloride, the LD50 for S-plus strain 84-32 was 43.3 times lower than its spontaneous S-minus mutant 84-54. Seven strains of inbred mice were no more susceptible than the outbred strain. In contrast to the findings with Salmonella typhimurium by others, 3 X 10(7) CFU of strain 84-32 caused 90% mortality in C3H/HeN (LPSn) mice and 40% mortality in C3H/HeJ (LPSd) mice. High-grade bacteremia in HA/ICR mice occurred after oral challenge with S-plus C. fetus strains and continued for at least 2 d, but was not present in any mice challenged with S-minus strains. Bacteremia at 30 min after challenge was 51.6-fold lower in mice pretreated with 10 microliters of rabbit antiserum to purified S-protein than after pretreatment with normal rabbit serum. Challenge of mice with a mixture of S-minus strain 84-54 and free S-proteins at a concentration 31.1-fold higher than found in wild-type strain 84-32 caused 30% mortality, compared with 0% with strain 84-54 or S-protein alone. These findings in a mouse model point toward the central role of the S-protein in the pathogenesis of C. fetus infection. The S-protein is not toxic per se, but enhances virulence when present on the bacterial cell surface as a capsule.
Pei
Z
Z
Medical Service, Veterans Administration Medical Center, Denver, Colorado.
Blaser
M J
MJ
D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis / Q000633:toxicity*; D002168:Campylobacter fetus / Q000472:pathogenicity*; D005260:Female; D007501:Iron / Q000378:metabolism; D007928:Lethal Dose 50; D008070:Lipopolysaccharides / Q000633:toxicity; D051379:Mice; D008809:Mice, Inbred C3H; D008813:Mice, Inbred ICR; D018805:Sepsis / Q000517:prevention & control; D013045:Species Specificity; D014774:Virulence
D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D007501:Iron