Experimental Infection Model for Johne's Disease in Sheep

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 po...

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Bibliographic Details
Published in:Infection and Immunity 2005-09, Vol.73 (9), p.5603-5611
Main Authors: Begg, D. J, O'Brien, R, Mackintosh, C. G, Griffin, J. F. T
Format: Article
Language:English
Subjects:
Administration, Oral
Animals
Bacterial Infections
Biological and medical sciences
Disease Models, Animal
Dose-Response Relationship, Immunologic
Fundamental and applied biological sciences. Psychology
Male
Microbiology
Mycobacterium avium
Mycobacterium avium subsp. paratuberculosis - immunology
Palatine Tonsil - immunology
Palatine Tonsil - microbiology
Paratuberculosis - immunology
Paratuberculosis - microbiology
Paratuberculosis - pathology
Ruminantia
Sheep
Sheep Diseases - immunology
Sheep Diseases - microbiology
Sheep Diseases - pathology
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Summary: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-passage-number 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 x 10⁸ 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.
ISSN:0019-9567
1098-5522
DOI:10.1128/IAI.73.9.5603-5611.2005