title: Dietary calcium modulates Mycobacterium paratuberculosis infection in beige mice.
abstract: A 6-month study was conducted to evaluate the effects of feeding different levels of dietary calcium (Ca) on the persistence of Mycobacterium paratuberculosis infection using a mouse model. Beige mice, averaging 8 weeks of age, were randomly assigned to one of the following dietary treatments: 1) 0.02% Ca, 2) 0.15% Ca, 3) 0.45% Ca, and 4) 1.0% Ca. Mice were infected intraperitoneally with 10(8) CFU viable M. paratuberculosis for 1, 3, and 6 month periods. Plasma Ca levels was unaffected by dietary Ca (x = 7.3 mg/dl). Plasma levels of 1,25(OH)2D3 was elevated significantly in 0.02% and 0.15% Ca groups compared to other treatments at the end of each period, with the highest levels observed for 0.02% Ca mice and intermediate values for 0.15% Ca mice. One month after infection, numbers of viable M. paratuberculosis cultured from the spleen were significantly reduced for 0.15% Ca mice, whereas the number of bacteria isolated from the liver and mesenteric lymph node (MLN) were higher for the 0.02% Ca group. There were no differences in bacterial numbers in the ileum although they tended to be higher for the 0.02% Ca group. Three months after infection, bacterial numbers in the spleen, ileum, and MLN did not differ across treatments, however, significantly lower numbers were found in the liver of 1.0% Ca mice. Reduced bacterial counts were also observed in the liver of 0.15%. 0.45%, and 1.0% Ca mice after a 6-month infection period compared to the 0.02% Ca group, with the lowest numbers isolated from the 1.0% Ca mice. Numbers of viable bacteria cultured from the ileum and MLN after 6 months of infection were also significantly reduced in 1.0% Ca mice. These results suggest that Ca metabolism is an important modulator of M. paratuberculosis infection.
authors.affiliation: Zoonotic Diseases Research Unit, NADC, ARS, USDA, Ames, IA 50010, USA. jstabel@nadc.ars.usda.gov
authors.forename: J R
authors.initials: JR
authors.lastname: Stabel
authors.forename: J P
authors.initials: JP
authors.lastname: Goff
authors.forename: M R
authors.initials: MR
authors.lastname: Ackermann
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016927:Mycobacterium avium subsp. paratuberculosis / Q000472:pathogenicity; D010283:Paratuberculosis / Q000378:metabolism*; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000378:metabolism / Q000382:microbiology / Q000473:pathology
chemical_list: D002136:Calcium, Dietary; D016207:Cytokines; D002117:Calcitriol