Transmission of Manheimia haemolytica from domestic sheep (Ovis aries) to bighorn sheep (Ovis canadensis): unequivocal demonstration with green fluorescent protein-tagged organisms

Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA.
Journal of wildlife diseases (Impact Factor: 1.36). 07/2010; 46(3):706-17. DOI: 10.7589/0090-3558-46.3.706
Source: PubMed


Previous studies demonstrated that bighorn sheep (Ovis canadensis) died of pneumonia when commingled with domestic sheep (Ovis aries) but did not conclusively prove that the responsible pathogens were transmitted from domestic to bighorn sheep. The objective of this study was to determine, unambiguously, whether Mannheimia haemolytica can be transmitted from domestic to bighorn sheep when they commingle. Four isolates of M. haemolytica were obtained from the pharynx of two of four domestic sheep and tagged with a plasmid carrying the genes for green fluorescent protein (GFP) and ampicillin resistance (AP(R)). Four domestic sheep, colonized with the tagged bacteria, were kept about 10 m apart from four bighorn sheep for 1 mo with no clinical signs of pneumonia observed in the bighorn sheep during that period. The domestic and bighorn sheep were then allowed to have fence-line contact for 2 mo. During that period, three bighorn sheep acquired the tagged bacteria from the domestic sheep. At the end of the 2 mo of fence-line contact, the animals were allowed to commingle. All four bighorn sheep died 2 days to 9 days following commingling. The lungs from all four bighorn sheep showed gross and histopathologic lesions characteristic of M. haemolytica pneumonia. Tagged M. haemolytica were isolated from all four bighorn sheep, as confirmed by growth in ampicillin-containing culture medium, PCR-amplification of genes encoding GFP and Ap(R), and immunofluorescent staining of GFP. These results unequivocally demonstrate transmission of M. haemolytica from domestic to bighorn sheep, resulting in pneumonia and death of bighorn sheep.

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Available from: Sarah Highlander, Sep 16, 2014
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    • "These same strains are typically present in domestic sheep, who carry them without suffering significant deleterious effects (Miller, 2001; Dassanayake et al., 2009; Lawrence et al., 2010). Pen experiments indicate that direct contact between domestic sheep and bighorn sheep result in a high likelihood of disease transmission to bighorn sheep, which are lethal to the latter species (Onderka et al., 1988; Foreyt, 1994; Foreyt and Silflow, 1996; Lawrence et al., 2010; Besser et al., 2012b). "
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    ABSTRACT: Bighorn sheep currently occupy just 30% of their historic distribution, and persist in populations less than 5% as abundant overall as their early 19th century counterparts. Present-day recovery of bighorn sheep populations is in large part limited by periodic outbreaks of respiratory disease, which can be transmitted to bighorn sheep via contact with domestic sheep grazing in their vicinity. In order to assess the viability of bighorn sheep populations on the Payette National Forest (PNF) under several alternative proposals for domestic sheep grazing, we developed a series of interlinked models. Using telemetry and habitat data, we characterized herd home ranges and foray movements of bighorn sheep from their home ranges. Combining foray model movement estimates with known domestic sheep grazing areas (allotments), a Risk of Contact Model estimated bighorn sheep contact rates with domestic sheep allotments. Finally, we used demographic and epidemiologic data to construct population and disease transmission models (Disease Model), which we used to estimate bighorn sheep persistence under each alternative grazing scenario. Depending on the probability of disease transmission following interspecies contact, extirpation probabilities for the seven bighorn sheep herds examined here ranged from 20% to100%. The Disease Model allowed us to assess the probabilities that varied domestic sheep management scenarios would support persistent populations of free-ranging bighorn sheep.
    Preventive Veterinary Medicine 04/2014; 113(1). DOI:10.1016/j.prevetmed.2014.01.008 · 2.17 Impact Factor
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    • "Disease continues to be a major obstacle to BHS recovery [1]. The transfer of pathogens, such as Mannheimia haemolytica, from domestic sheep (Ovis aires) to BHS and between BHS herds has caused numerous mortality events and has been modeled under experimental conditions [4-6]. While less well characterized, cervids like white-tailed deer (Odocoileus virginianus), mule deer (O. "
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    ABSTRACT: Transmissible spongiform encephalopathies (TSEs) affect both domestic sheep (scrapie) and captive and free-ranging cervids (chronic wasting disease; CWD). The geographical range of bighorn sheep (Ovis canadensis; BHS) overlaps with states or provinces that have contained scrapie-positive sheep or goats and areas with present epizootics of CWD in cervids. No TSEs have been documented in BHS, but the susceptibility of this species to TSEs remains unknown. We acquired a library of BHS tissues and found no evidence of preexisting TSEs in these animals. The prion protein gene (Prnp) in all BHS in our library was identical to scrapie-susceptible domestic sheep (A136R154Q171 genotype). Using an in vitro prion protein conversion assay, which has been previously used to assess TSE species barriers and, in our study appears to recollect known species barriers in mice, we assessed the potential transmissibility of TSEs to BHS. As expected based upon Prnp genotype, we observed BHS prion protein conversion by classical scrapie agent and evidence for a species barrier between transmissible mink encephalopathy (TME) and BHS. Interestingly, our data suggest that the species barrier of BHS to white-tailed deer or wapiti CWD agents is likely low. We also used protein misfolding cyclic amplification to confirm that CWD, but not TME, can template prion protein misfolding in A136R154Q171 genotype sheep. Our results indicate the in vitro conversion assay used in our study does mimic the species barrier of mice to the TSE agents that we tested. Based on Prnp genotype and results from conversion assays, BHS are likely to be susceptible to infection by classical scrapie. Despite mismatches in amino acids thought to modulate prion protein conversion, our data indicate that A136R154Q171 genotype sheep prion protein is misfolded by CWD agent, suggesting that these animals could be susceptible to CWD. Further investigation of TSE transmissibility to BHS, including animal studies, is warranted. The lack of reported TSEs in BHS may be attributable to other host factors or a lack of TSE surveillance in this species.
    BMC Veterinary Research 08/2013; 9(1):157. DOI:10.1186/1746-6148-9-157 · 1.78 Impact Factor
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    • "Much of this research was conducted under captive conditions or in vitro, due to the challenges of identifying morbid or recently dead animals that are appropriate for sampling, variation in methods for investigating outbreaks, and other challenges for conducting field investigations on bighorn sheep diseases. Recent evidence confirms that transmission of Mannheimia haemolytica (formerly Pasteurella haemolytica) from domestic sheep to bighorn sheep can occur under experimental conditions when comingling [18]. Alternative hypotheses that are not mutually exclusive with pasteurellosis include other infectious agents, external stressors, and nutritional deficiencies that can lead to compromised bighorn sheep immunity to infectious disease [19– 21]. "
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    ABSTRACT: Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain, Mycoplasma sp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents.
    Veterinary Medicine International 11/2011; 2011:162520. DOI:10.4061/2011/162520
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