Pathogenesis of Mycobacterium avium subsp. paratuberculosis in neonatal calves after oral or intraperitoneal experimental infection

Modeling the Effect of Direct and Indirect Contamination of On-Farm Bulk Tank Milk with Mycobacterium avium subsp. paratuberculosis

“…Briefly, in the early stage of infection, the host response is predominantly a cell-mediated immune response (CMI), where the infection remains latent but MAP proliferates in the jejunum and ileum and spreads to local lymph nodes. The cow may shed MAP in feces at low levels, often below the detection limit, and possibly also in milk if disseminated infection has occurred (Sweeney et al, 2006;Stabel et al, 2009). The latter is still uncertain.…”

Induction of B Cell Responses upon Experimental Infection of Neonatal Calves with Mycobacterium avium subsp. paratuberculosis

“…As previously described (19), neonatal Holstein dairy calves obtained from status level 4 herds enrolled in the Voluntary Bovine Johne's Control Program were purchased at 1 to 2 days of age and housed in biosafety level 2 containment barns for the duration of the study. Control calves were housed in a barn separate from the experimentally infected animals.…”

“…group (n ϭ 4), and (v) oral/mucosal (oral/M) group (n ϭ 3). Descriptions of the inoculum preparation and the route of inoculation are provided in a previously published manuscript (19). Briefly, on day 0 of the study, the oral and oral/DXM groups were fed milk replacer containing, on average, 1 ϫ 10 11 live M. avium subsp.…”

“…Intraperitoneal inoculation of calves was performed on days 0, 7, 14, and 21 of the study by inoculation of 1 ml of M. avium subsp. paratuberculosis (10 11 bacteria) through a 3-mm incision in the right flank (19). The oral/M group calves were inoculated on days 0, 7, and 14 of the study by being fed milk replacer containing 2.6 ϫ 10 12 live M. avium subsp.…”

“…and the strain of M. avium subsp. paratuberculosis used for inoculation (laboratory strain versus clinical isolate) impacted the degree of tissue colonization in a 12-month study (19). Calves inoculated orally with a clinical isolate of M. avium subsp.…”