Serological evidence for historical and present-day exposure of North American bison to Mycoplasma bovis.

BACKGROUND: Mycoplasma bovis causes mastitis, otitis, pneumonia and arthritis in cattle and is a major contributor to bovine respiratory disease complex. Around the year 2000, it emerged as a significant threat to the health of North American bison. Whether healthy bison are carriers of M. bovis and when they were first exposed is not known. To investigate these questions we used a commercially available ELISA that detects antibodies to M. bovis to test 3295 sera collected from 1984 through 2019 from bison in the United States and Canada. RESULTS: We identified moderately to strongly seropositive bison from as long ago as the late 1980s. Average seroprevalence over the past 36 years is similar in the United States and Canada, but country-specific differences are evident when data are sorted by the era of collection. Seroprevalence in the United States during the pre-disease era (1999 and prior) was significantly higher than in Canada, but was significantly lower than in Canada during the years 2000-2019. Considering individual countries, seroprevalence in the United States since the year 2000 dropped significantly as compared to the years 1985-1999. In Canada the trend is reversed, with seroprevalence increasing significantly since the year 2000. ELISA scores for sera collected from free-ranging bison do not differ significantly from scores for sera from more intensively managed animals, regardless of the era in which they were collected. However, seroprevalence among intensively raised Canadian bison has nearly doubled since the year 2000 and average ELISA scores rose significantly. CONCLUSIONS: Our data provide the first evidence that North American bison were exposed to M. bovis many years prior to the emergence of M. bovis-related disease. Patterns of exposure inferred from these results differ in the United States and Canada, depending on the era under consideration. Our data further suggest that M. bovis may colonize healthy bison at a level sufficient to trigger antibody responses but without causing overt disease. These findings provide novel insights as to the history of M. bovis in bison and will be of value in formulating strategies to minimize the impact of mycoplasmosis on bison health and production.

Comparison of multilocus sequence types found among North American isolates of Mycoplasma bovis from cattle, bison, and deer, 2007-2017.

A prior multilocus sequence typing (MLST) study reported that Mycoplasma bovis isolates from North American bison possess sequence types (STs) different from those found among cattle. The 42 bison isolates evaluated were obtained in 2007 or later, whereas only 19 of 94 (~20%) of the available cattle isolates, with only 1 from North America, were from that same time. We compared STs of additional, contemporary, North American cattle isolates with those from bison, as well as isolates from 2 North American deer, all originating during the same timeframe, to more definitively assess potential strain-related host specificity and expand our understanding of the genetic diversity of M. bovis. From 307 isolates obtained between 2007 and 2017 (209 from cattle, 96 from bison, 2 from deer), we identified 49 STs, with 39 found exclusively in cattle and 5 exclusively in bison. Four STs were shared between bison and cattle isolates; one ST was found in cattle and in a deer. There was no clear association between ST and the health status of the animal of origin. An MLST-based phylogeny including 41 novel STs identified in our study reveals that STs found in bison fall within several divergent lineages that include STs found exclusively in cattle.

Potential Bacillus anthracis Risk Zones for Male Plains Bison ( Bison bison bison) in Southwestern Montana, USA.

A re-emergence of anthrax, a zoonosis caused by the long-lived, spore-forming Bacillus anthracis, occurred with a multispecies outbreak in southwestern Montana, US in 2008. It substantially impacted a managed herd of about 3,500 free-ranging plains bison ( Bison bison bison) on a large, private ranch southwest of Bozeman, with about 8% mortality and a disproportionate 28% mortality of mature males; a similar high rate occurred in male Rocky Mountain elk ( Cervus canadensis nelson). Grazing herbivores are particularly at risk for anthrax from ingesting spore-contaminated soil and grasses in persistent environmental reservoirs. We predicted areas of mature male bison habitat preference on the landscape by using GPS collar data and a resource selection function model using environmental covariates. We overlaid preferred areas with ecologic niche, model-based predictions of B. anthracis environmental reservoirs to identify areas of high anthrax risk. Overlapping areas were distributed across the ranch and were not confined to pastures associated with the previous outbreak, suggesting that ongoing pasture exclusion alone will not prevent future outbreaks. The data suggested vaccination campaigns should continue for bison, and the results can be used to prioritize carcass surveillance in areas of greatest overlap.

Dances with anthrax: wolves (Canis lupus) kill anthrax bacteremic plains bison (Bison bison bison) in southwestern Montana.

Bacillus anthracis, the cause of anthrax, was recovered from two plains bison (Bison bison bison) cows killed by wolves (Canis lupus) in Montana, USA, without associated wolf mortality in July 2010. This bison herd experienced an epizootic in summer 2008, killing ∼ 8% of the herd, the first documented in the region in several decades. No wolf deaths were associated with the 2008 event. Surveillance has continued since 2008, with research, ranch, and wildlife personnel diligent during summer. As part of this, we tested wolf-killed bison and elk (Cervus elaphus) for anthrax during the 2010 summer using lateral flow immunochromatographic assays (LFIA). Two bison cows were positive for protective antigen, confirming active bacteremia. The LFIA results were confirmed with traditional bacteriology recovering viable B. anthracis. No wolf fatalities were associated with the bison deaths, despite consuming the meat. Low-level anthrax occurrence in large, rough terrain landscapes remains difficult to detect, particularly if mortality in the herbivore host is not a consequence of infection. In these instances, surveillance of predators with large home ranges may provide a more sensitive indicator of anthrax emergence or reemergence in such systems. Though speculative, it is also possible that anthrax infection in the bison increased predation risk. These results also suggest B. anthracis remains a threat to wildlife and associated livestock in southwestern Montana.

Phenotypic effects of cattle mitochondrial DNA in American bison.

Hybridization between endangered species and more common species is a significant problem in conservation biology because it may result in extinction or loss of adaptation. The historical reduction in abundance and geographic distribution of the American plains bison (Bison bison bison) and their recovery over the last 125 years is well documented. However, introgression from domestic cattle (Bos taurus) into the few remaining bison populations that existed in the late 1800s has now been identified in many modern bison herds. We examined the phenotypic effect of this ancestry by comparing weight and height of bison with cattle or bison mitochondrial DNA (mtDNA) from Santa Catalina Island, California (U.S.A.), a nutritionally stressful environment for bison, and of a group of age-matched feedlot bison males in Montana, a nutritionally rich environment. The environmental and nutritional differences between these 2 bison populations were very different and demonstrated the phenotypic effect of domestic cattle mtDNA in bison over a broad range of conditions. For example, the average weight of feedlot males that were 2 years of age was 2.54 times greater than that of males from Santa Catalina Island. In both environments, bison with cattle mtDNA had lower weight compared with bison with bison mtDNA, and on Santa Catalina Island, the height of bison with cattle mtDNA was lower than the height of bison with bison mtDNA. These data support the hypothesis that body size is smaller and height is lower in bison with domestic cattle mtDNA and that genomic integrity is important for the conservation of the American plains bison.

Complete mitochondrial DNA sequence analysis of Bison bison and bison-cattle hybrids: function and phylogeny.

Complete mitochondrial DNA (mtDNA) genomes from 43 bison and bison-cattle hybrids were sequenced and compared with other bovids. Selected animals reflect the historical range and current taxonomic structure of bison. This study identified regions of potential nuclear-mitochondrial incompatibilities in hybrids, provided a complete mtDNA phylogenetic tree for this species, and uncovered evidence of bison population substructure. Seventeen bison haplotypes defined by 66 polymorphic sites were discovered, whereas 728 fixed differences and 86 non-synonymous mutations were identified between bison and bison-cattle hybrid sequences. The potential roles of the mtDNA genome in the function of hybrid animals and bison taxonomy are discussed.

Using the community of inquiry methodology in teaching bioethics: a focus on skills development.

The community of inquiry methodology was developed by Professor Matthew Lipman to enable the teaching of philosophy in schools. Lipman felt that inquiry-based learning was essential in schools because: Education should empower children to be thoughtful about the lives they lead, and doing philosophy is important to that goal. The community of inquiry is a powerful pedagogical tool to foster student engagement, critical thinking, and collaborative and affective skills development. As such it can be useful in the bioethics classroom. This article describes the community of inquiry methodology and how it can be a useful arrow in quiver to a teacher of bioethics.

Microorganisms associated with a pneumonic epizootic in Rocky Mountain bighorn sheep (Ovis canadensis canadensis).

A comprehensive study of a pneumonic epizootic was initiated when the first signs of disease were noted in a metapopulation of bighorn sheep inhabiting Hells Canyon, bordering Idaho, Oregon, and Washington. A total of 92 bighorn sheep were tested for etiologic agents during the following 6-mo study period. The study population included bighorn sheep believed to be the subpopulation in which disease was first noted, and these sheep were translocated to a holding facility in an effort to contain the disease (group A1, n = 72); bighorn sheep in other subpopulations (group A2) with evidence of clinical disease were captured, sampled, given antibiotics, and released (n = 8) and those that were found dead were necropsied (n = 12). Samples, including oropharyngeal and nasal swabs, and lung and liver tissue were collected from the bighorn sheep identified above. Tissue was collected at necropsy from 60 group A1 bighorn sheep that died following translocation, and samples were cultured for bacteria and viruses. Blood samples were tested for antibodies against known respiratory viruses, and histopathology was conducted on tissue samples. The major cause of death in both group A1 and group A2 bighorn sheep was a rapidly developing fibrinous bronchopneumonia. Multiple biovariants of Pasteurella were isolated from oropharyngeal and nasal samples from both groups, and Mycoplasma ovipneumonia was isolated from five group A1 oropharyngeal samples. Organisms isolated from lung tissue included Pasteurella multocida multocida a and Pasteurella trehalosi, both of which differentiated into multiple strains by restriction enzyme analysis, and parainfluenza-3 virus (PI-3). Paired serum samples revealed > fourfold increases in titers against PI-3 and bovine respiratory syncytial viruses. It was concluded that this epizootic resulted from a complex of factors including multiple potential respiratory pathogens, none of which were identified as a primary pathogen, and possible stress factors.

Sharing of Pasteurella spp. between free-ranging bighorn sheep and feral goats.

Pasteurella spp. were isolated from feral goats and free-ranging bighorn sheep (Ovis canadensis canadensis) in the Hells Canyon National Recreation Area bordering Idaho, Oregon, and Washington (USA). Biovariant 1 Pasteurella haemolytica organisms were isolated from one goat and one of two bighorn sheep found in close association. Both isolates produced leukotoxin and had identical electrophoretic patterns of DNA fragments following cutting with restriction endonuclease HaeIII. Similarly Pasteurella multocida multocida a isolates cultured from the goat and one of the bighorn sheep had D type capsules, serotype 4 somatic antigens, produced dermonecrotoxin and had identical HaeIII electrophoretic profiles. A biovariant U(beta) P.haemolytica strain isolated from two other feral goats, not known to have been closely associated with bighorn sheep, did not produce leukotoxin but had biochemical utilization and HaeIII electrophoretic profiles identical to those of isolates from bighorn sheep. It was concluded that identical Pasteurella strains were shared by the goats and bighorn sheep. Although the direction of transmission could not be established, evidence suggests transmission of strains from goats to bighorn sheep. Goats may serve as a reservoir of Pasteurella strains that may be virulent in bighorn sheep; therefore, goats in bighorn sheep habitat should be managed to prevent contact with bighorn sheep. Bighorn sheep which have nose-to-nose contact with goats should be removed from the habitat.