|Knowles, Donald - Don|
|Marciel, Ann Marie|
Submitted to: Journal of Wildlife Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2010
Publication Date: 7/8/2010
Publication URL: http://www.ncbi.nlm.nih.gov/pubmed/20688676
Citation: Lawrence, P.K., Shanthalingam, S., Dassanayake, R.P., Subramaniam, R., Herndon, C.N., Knowles Jr, D.P., Rurangirwa, F.R., Foreyt, W.J., Wayman, G., Marciel, A., Highlander, S.K., Subramaniam, S. 2010. Transmission of mannheimia haemolytica from domestic sheep (ovis aries) to bighorn sheep (ovis canadensis) : Unequivocal demonstration with green fluorescent protien-tagged organisms. Journal of Wildlife Diseases. 46(3):706-17. Interpretive Summary: Pneumonia is a population limiting disease in bighorn sheep. The risk of pathogen transmission to or among bighorn sheep under natural conditioners is not known. These data report the use of a tagged pathogen (Mannheimia haemolytica) to trace and determine transmission risks dependent on distance between domestic and wildlife species. Clinical disease in bighorn sheep required extensive contact with domestic sheep. These data will help guide disease management practices under range conditions.
Technical Abstract: Previous studies have demonstrated that bighorn sheep (BHS) die of pneumonia when they commingle with domestic sheep (DS). However, these studies did not conclusively prove the transmission of pathogens from DS to BHS. The objective of this study was to determine unambiguously whether Mannheimia haemolytica, the most important respiratory pathogen of BHS, is transmitted from DS to BHS when they commingle. M. haemolytica was obtained from the pharynx of four DS and tagged with a plasmid carrying the genes for green fluorescent protein (GFP) and beta-lactamase (bla). Four DS colonized with the tagged bacteria were kept 30 ft apart from four BHS for one month. No transmission of the tagged bacteria was observed during this period. The DS and BHS were then allowed to have fence line contact for two months. During this period two BHS contracted the tagged bacteria from the DS. At the end of the two months the animals were allowed to commingle. One BHS died on day two, two died on day five, and the fourth one was euthanized on day nine following commingling. The lungs from all four BHS showed gross- and histo-pathological lesions characteristic of M. haemolytica pneumonia. M. haemolytica isolated from all four BHS were confirmed to be the tagged bacteria from the DS by their growth in ampicillin-containing growth medium, PCR-amplification of genes encoding GFP and beta-lactamase, and immunofluorescent staining of GFP. These results unequivocally prove transmission of M. haemolytica from DS to BHS which results in pneumonia and death of BHS.