Intestinal infection following aerosol challenge of calves with Mycobacterium avium subspecies paratuberculosisReport as inadecuate

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Veterinary Research

, 42:117

First Online: 03 December 2011Received: 19 August 2011Accepted: 03 December 2011


A challenge experiment was performed to investigate whether administration of Mycobacterium avium subsp. paratuberculosis MAP via the respiratory route leads to MAP infection in calves. Eighteen calves from test negative dams were randomly allocated to four groups. Six calves were challenged with MAP nasally and six calves were challenged by transtracheal injection; three orally challenged calves served as positive controls, and three non challenged calves as negative controls. The challenge was performed as a nine-fold trickle dose, 10 CFU in total. Blood and faecal samples were collected frequently. Calves were euthanized three months post-challenge and extensively sampled. Blood samples were tested for the presence of antibodies and interferon gamma producing cells by ELISA. Faecal and tissue samples were cultured in a liquid culture system and the presence of MAP was confirmed by IS900 realtime PCR. Fourteen out of fifteen calves had no MAP antibody response. The negative controls remained negative; all positive controls became infected. Two nasally challenged calves showed a Purified Protein Derivative Avian PPDA specific interferon gamma response. In all nasally challenged calves, MAP positive intestinal samples were detected. In three calves of the nasal group MAP positive retropharyngeal lymph nodes or tonsils were detected. In all calves of the transtracheal group MAP positive intestinal tissues were detected as well and three had a MAP positive tracheobronchial lymph node. These findings indicate that inhalation of MAP aerosols can result in infection. These experimental results may be relevant for transmission under field conditions since viable MAP has been detected in dust on commercial dairy farms.

Electronic supplementary materialThe online version of this article doi:10.1186-1297-9716-42-117 contains supplementary material, which is available to authorized users.

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Author: Susanne WF Eisenberg - Ad P Koets - Mirjam Nielen - Dick Heederik - Rienske Mortier - Jeroen De Buck - Karin Orsel


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