Early immune events following experimental infection of lambs with <i>Mycobacterium avium</i> subspecies <i>paratuberculosis</i>

BEGARA-McGORUM, Isabel M.; Wildblood, L. A.; Jones, Douglas

doi:10.1042/bst025279s

Cited by 5 publications

(6 citation statements)

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“…paratuberculosis was investigated. 2,3 As in the present study, the percentage of T cells was greater and the percentage of B cells was lower 8 weeks after infection. Unlike the present study, cdT cells were reported to increase.…”

Section: Discussionmentioning

confidence: 39%

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Mucosal Immune Response in Cattle with Subclinical Johne's Disease

2006

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Mycobacterium avium subsp. paratuberculosis is the causative agent of Johne's disease, a chronic granulomatous enteritis of wild and domestic ruminants. During a long subclinical period, the organism persists in the intestine despite systemic cellular and humoral immune responses. To explore the mucosal immune response in Johne's disease, we isolated mononuclear leukocytes from the ileum of cows naturally infected with M. avium subsp. paratuberculosis and from cows that were not infected. We evaluated the immunophenotype of these cells and the proliferative responses after the addition of M. avium subsp. paratuberculosis sonicate or B-cell or T-cell mitogens. Although the percentage of T cells was increased in infected cows, these cells consisted mostly of memory (CD2+CD62L-) and regulatory (CD4+CD25+) T cells. Further evidence of immune hyporesponsiveness included a decrease in the percentage of T cells with an activated phenotype and a decrease in cells expressing major histocompatibility factor class II (MHC class II). Unlike the spleen, ileal lymphocytes from infected cows failed to proliferate in response to M. avium subsp. paratuberculosis sonicate. Additionally, ileal lymphocytes from infected cows proliferated poorly in response to concanavalin A and pokeweed mitogen, suggesting generalized T cell and B cell hyporesponsiveness. These results indicate that a state of tolerance may exist in the intestine of cows subclinically infected with M. avium subsp. paratuberculosis organisms in subclinically infected cows. This effect may be induced, at least in part, by proliferation of regulatory T cells that nonspecifically suppress mucosal immune responsiveness.

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Section: Discussionmentioning

confidence: 39%

“…paratuberculosis. 1,3,6,7,22 The distribution of lymphocytes in the ileal Peyer's patches of lambs experimentally infected with M. avium subsp. paratuberculosis was investigated.…”

Section: Discussionmentioning

confidence: 99%

Mucosal Immune Response in Cattle with Subclinical Johne's Disease

2006

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“…Published data using sheep as a model have used strains of M. avium subsp. paratuberculosis sourced from cattle (24), deer (3,4), and sheep (20,40). This may explain in part the differing outcomes, as bovine and ovine strains of M. avium subsp.…”

Section: Discussionmentioning

confidence: 94%

“…Sheep challenged with M. avium subsp. paratuberculosis isolated from cattle, deer, and sheep become infected or develop clinical disease (3,4,7,16,24,40). The infecting bacteria can be either a direct tissue isolate (22,24,44) or passaged by serial laboratory culture (42,44) in vitro.…”

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confidence: 99%

Experimental Infection Model for Johne's Disease in Sheep

et al. 2005

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Johne's disease in ruminants results in chronic enteritis caused by the pathogenic bacterium Mycobacterium avium subsp. paratuberculosis. This study examined two M. avium subsp. paratuberculosis strains (JD3 and W), using different doses and routes of infection, to establish the optimal time postchallenge when predictable levels of infection, gut lesions, and clinical disease occur in a large proportion of sheep. While a small proportion (25%) of sheep challenged with a low-passage-number laboratory culture of M. avium subsp. paratuberculosis (strain W) became infected, no infection was found in animals exposed to a high-passagenumber culture isolate of strain W. In contrast, a primary tissue homogenate of M. avium subsp. paratuberculosis (JD3) resulted in high (90%) infection rates and gut histopathology following oral or intratonsillar challenge. The optimal conditions necessary to produce Johne's disease involve oral inoculation of 3-month-old lambs with four doses of 5 ؋ 10 8 CFU of M. avium subsp. paratuberculosis isolated directly from the gut lymphatic tissues of clinically affected sheep. This resulted in consistent gut histopathology at 9 months and the onset of clinical disease by 11 months postchallenge.

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“…Other studies also show differences in ovine responses to experimental infection with different MAP strains, including strains of bovine (Kluge et al., 1968), deer (Begara‐McGorum et al., 1997, 1998 and ovine origin (Gwózdz and Thompson, 2002 ; Reddacliff and Whittington, 2003 ). These differences may be due to the fact that bovine and ovine strains show different phenotypic characteristics in vivo (Marsh et al., 1999; Stewart et al., 2004 ) and express different properties in vitro (Whittington et al., 1999).…”

Section: Discussionmentioning

confidence: 95%

Variation in the Immuno‐pathological Responses of Lambs after Experimental Infection with Different Strains ofMycobacterium aviumsubsp.paratuberculosis

Verna

García-Pariente

Muñoz

et al. 2007

Zoonoses and Public Health

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Ruminant infection by Mycobacterium avium subsp. paratuberculosis (MAP) causes a granulomatous inflammatory response in the intestine and associated lymph nodes. Differences either in the affected organs or in the inflammatory infiltrate were observed between species and individuals. Such differences are usually attributed to variations in host immune responses or to inconsistent effects among different MAP strains. To evaluate if different MAP strains induce different immuno-pathological responses in lambs, 28 one-month-old individuals were divided into six groups and inoculated with different MAP strains. Groups 1 and 2 were inoculated with two bovine strains isolated in Argentina that showed different genetic patterns after BstEII-IS900-RFLP (hereafter strains E and A respectively). Group 3 was inoculated with a bovine strain isolated in Spain obtained after a previous step of culture (patterns C1). Group 4 was inoculated with a homogenate of intestinal mucosa of a clinical case affected by the same bovine strain as that of group 3. Group 5 was inoculated with an ovine strain that was directly purified from the intestinal mucosa of a clinical case, and group 6 was kept as control (i.e. no inoculation). Peripheral immune responses were assessed until 150 days post-infection (dpi), when lambs were humanely killed. Pathological studies were performed in tissues from the intestine and lymph nodes. Lesion types and inflammatory infiltrates were examined as indicators of pathogenicity. All the lambs infected with bovine MAP strains showed a common lesion pattern regardless of the strain type. Such pattern was characterized by focal lesions mainly in the mesenteric lymph nodes, the presence of fibrous tissue, and, occasionally, necrosis in the granulomas as well as the presence of numerous giant cells. Differences in lesion severity were observed among groups: lambs from groups 1 and 2 had the highest number of granulomas and the largest lymph node area affected. Lesions in animals from group 5 (infected with an ovine strain) were more severe and occurred mostly in the intestinal lymphoid tissue; necrosis, fibrosis or giant cells were never detected in this group. These results indicate that the MAP strain type induces different pathological responses in lambs.

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Early immune events following experimental infection of lambs with Mycobacterium avium subspecies paratuberculosis

Cited by 5 publications

References 1 publication

Mucosal Immune Response in Cattle with Subclinical Johne's Disease

Mucosal Immune Response in Cattle with Subclinical Johne's Disease

Experimental Infection Model for Johne's Disease in Sheep

Variation in the Immuno‐pathological Responses of Lambs after Experimental Infection with Different Strains ofMycobacterium aviumsubsp.paratuberculosis

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