Evaluating Two Sampling Methods for Mycoplasma Bovis Diagnosis in American Bison (Bison bison)

Mycoplasma bovis is a bacterial pathogen endemic to cattle. In the early 2000s, M. bovis emerged as a cause of respiratory disease in American bison (Bison bison), causing significant morbidity and mortality. Bison herds that experience an outbreak of M. bovis are at higher risk for subsequent outbreaks, suggesting that chronic, subclinical infections can be established. Antemortem testing is therefore crucial to disease management; however, the precise sampling method to maximize detection of M. bovis in bison is unknown. We evaluated two sample types-superficial nasal swabs and deep nasopharyngeal swabs-collected from apparently healthy or symptomatic bison from January 2021 through December 2022. We used real-time PCR to detect M. bovis in 76/938 bison (8.1%) from 11 herds. For bison testing positive on at least one swab type, M. bovis was detected in 63/76 (82.8%) deep nasopharyngeal swabs and 29/73 (38.1%) superficial nasal swabs. Agreement between swabs for positive bison was 21% (n=16, kappa coefficient 0.319). We conclude that deep nasopharyngeal swabbing is more sensitive than superficial nasal swabbing for detection of M. bovis in bison and that low agreement between methods may be related to stage of infection. We further tested pooled samples by PCR and found that pooling of up to five samples can be effective to increase throughput and minimize costs. Management of wild bison relies on the ability to relocate animals to maintain gene flow and healthy populations. Sensitive and specific diagnostic tests are needed to inform decisions and minimize risk of transmission, especially from subclinical carriers. This study provides valuable insight that will inform best practices for M. bovis testing, thereby supporting the conservation of bison as healthy wildlife, which in turn promotes ecological restoration, safeguards cultural practices of Tribal Nations, and upholds the bison as a unique American icon.

Serum IgG Immunoglobulin Levels are Associated with Reduced PCR Detection of Mycoplasma bovis in Naturally Infected American Bison (Bison bison)

Mycoplasma bovis (M. bovis) is an important pathogen of American bison (Bison bison), associated with high morbidity and mortality epizootics of respiratory and reproductive disease. Despite the significant negative impact on bison health, little is known about the kinetics of disease and the host immune response to infection. To address these questions, a cohort of bison calves was created and serially sampled 5 times, once every 2-3 mo, over a 12-mo period. At each sampling period nasal swab samples were collected and tested by PCR for the presence of M. bovis. Serum samples were also collected and assessed for M. bovis-specific antibodies using both a commercial and an in-house ELISA. Overall, 19/41 bison (46.3%) had positive PCR tests, and 31/41 (75.6%) were seropositive. Over the course of the study, the frequency of PCR-positive nasal swabs and the ELISA scores decreased, although serum samples remained positive for at least 6 mo following the final positive PCR test. Bison were grouped according to results from the in-house ELISA into high-responder (n=7), low-responder (n=5), and seronegative (n=7) groups. M. bovis-specific IgG antibody levels were significantly elevated in the high-responder group compared to the low-responder and seronegative groups. The differences were statistically significant for 3/5 sampling periods. A trend toward increased IgG2 levels was observed in the high-responder group. High total IgG responses correlated with a decline in positive PCR tests from nasal swabs. These data provide evidence that a strong humoral response is beneficial and is probably involved in the clearance of M. bovis from bison.

An injectable subunit vaccine containing Elongation Factor Tu and Heat Shock Protein 70 partially protects American bison from Mycoplasma bovis infection

Mycoplasma bovis (M. bovis) is the etiologic agent of high mortality epizootics of chronic respiratory disease in American bison (Bison bison). Despite the severity of the disease, no efficacious commercial vaccines have been licensed for the prevention of M. bovis infection in bison. Elongation factor thermal unstable (EFTu) and Heat Shock Protein 70 (Hsp70, DnaK) are highly conserved, constitutively expressed proteins that have previously been shown to provide protection against M. bovis infection in cattle. To assess the suitability of EFTu and Hsp70 as vaccine antigens in bison, the immune response to and protection conferred by an injectable, adjuvanted subunit vaccine comprised of recombinantly expressed EFTu and Hsp70 was evaluated. Vaccinates developed robust antibody and cellular immune responses against both EFTu and Hsp70 antigens. To assess vaccine efficacy, unvaccinated control and vaccinated bison were experimentally challenged with bovine herpes virus-1 (BHV-1) 4 days prior to intranasal infection with M. bovis. Vaccinated bison displayed reductions in joint infection, lung bacterial loads, and lung lesions compared to unvaccinated controls. Together, these results showed that this subunit vaccine reduced clinical disease and bacterial dissemination from the lungs in M. bovis challenged bison and support the further development of protein subunit vaccines against M. bovis for use in bison.

Diversity and antigenic potentials of Mycoplasmopsis bovis secreted and outer membrane proteins within a core genome of strains isolated from North American bison and cattle

Mycoplasmopsis bovis is a worldwide economically important pathogen of cattle that can cause or indirectly contribute to bovine respiratory disease. M. bovis is also a primary etiological agent of respiratory disease in bison with high mortality rates. A major challenge in the development of an efficacious M. bovis vaccine is the design of antigens that contain both MHC-1 and MHC-2 T-cell epitopes, and that account for population level diversity within the species. Publicly available genomes and sequence read archive libraries of 381 M. bovis strains isolated from cattle (n = 202) and bison (n = 179) in North America were used to identify a core genome of 575 genes, including 38 that encode either known or predicted secreted or outer membrane proteins. The antigenic potentials of the proteins were characterized by the presence and strength of their T-cell epitopes, and their protein variant diversity at the population-level. The proteins had surprisingly low diversity and varying predictive levels of T-cell antigenicity. These results provide a reference for the selection or design of antigens for vaccine testing against strains infecting North American cattle and bison.

A serological survey of pathogens associated with the respiratory and digestive system in the Polish European bison (Bison bonasus) population in 2017-2022

BACKGROUND

The European bison (Bison bonasus) is a near threatened species and requires health monitoring. The aim of the present study was to determine the prevalence of antibodies to pathogens known to cause respiratory and digestive illness in ruminants.

RESULTS

In the studied 328 European bison, the highest seroprevalence was observed for Bovine herpesvirus-1 (BoHV-1) (50.27%), Bovine Coronavirus (BCoV) (26.36%), and Bluetongue Virus (BTV) (12.83%). For Mycoplasma bovis strains and Bovine Viral Diarrhea Virus (BVDV), positive results were rare. Interestingly, a higher prevalence of BTV antibodies was noted in the northeastern populations and older animals.

CONCLUSIONS

Our findings indicate that the Polish European bison population appears to have considerable contact with BoHV-1; however, this does not appear to be of great significance, as clinical symptoms and post-mortem lesions are rarely noted in Polish European bison population. The high seroprevalence of BTV in the north-east of Poland is an ongoing trend, also noted in previous studies. It is possible that European bison may perpetuate the virus in this region. This is the first report of antibodies for BCoV in European bison.

Production of granulomas in Mycoplasma bovis infection associated with meningitis-meningoencephalitis, endocarditis, and pneumonia in cattle

Mycoplasma bovis, the most important primary pathogen in the family Mycoplasmataceae, causes pneumonia, arthritis, otitis media, and mastitis in cattle. Histopathologic pulmonary changes associated with M. bovis infection have been characterized as suppurative-to-caseonecrotic bronchopneumonia; infection in other organs has been reported in only a few studies that examined caseonecrotic endocarditis and suppurative meningitis. Granulomatous lesions associated with M. bovis infection have been reported only rarely. We studied the granulomatous inflammation associated with M. bovis infection in several organs of 21 Japanese Black cattle. M. bovis was detected by isolation and loop-mediated isothermal amplification methods; other bacteria were detected using culture on 5% blood sheep agar and a MALDI-TOF MS Biotyper. Tissues were examined by histopathology and by immunohistochemistry (IHC) using anti-M. bovis, anti-Iba1, anti-iNOS, and anti-CD204 antibodies. All 21 cases, which included 2 cases of meningitis-meningoencephalitis, 8 cases of endocarditis, and 11 cases of bronchopneumonia, had caseonecrotic granulomatous inflammation associated with M. bovis infection. The IHC for macrophages revealed a predominance of iNOS-labeled (M1) macrophages in the inner layer of the caseonecrotic granulomas associated with meningitis-meningoencephalitis, endocarditis, and bronchopneumonia in Japanese Black cattle naturally infected with M. bovis.

Prevalence of Mycoplasma spp. in the Respiratory Tract of Healthy North American Bison (Bison bison) and Comparison with Serum Antibody Status

Mycoplasma bovis is a primary cause of respiratory and reproductive diseases in North American bison (Bison bison), with significant morbidity and mortality. The epidemiology of M. bovis in bison is poorly understood, hindering efforts to develop effective control measures. Our study considered whether healthy bison might be carriers of M. bovis, potentially serving as unrecognized sources of exposure. We used culture and PCR to identify mycoplasmas in the nasal cavity or tonsil of 499 healthy bison from 13 herds and two abattoirs in the US and Canada. Mycobacterium bovis was detected in 15 bison (3.0%) representing two herds in the US and one in Canada, while M. bovirhinis, M. bovoculi, M. arginini, or M. dispar was identified from an additional 155 bison (31.1%). Mycoplasma bovirhinis was identified most frequently, in 142 bison (28.5%) representing at least 10 herds. Of the 381 bison for which serum was available, only 6/13 positive for M. bovis (46.2%) tested positively with an M. bovis ELISA, as did 19/368 negative for M. bovis (5.2%). Our data reveal that M. bovis can be carried in the upper respiratory tract of healthy bison with no prior history or clinical signs of mycoplasmosis and that a large proportion of carriers may not produce detectable antibodies. Whether carriage of other mycoplasmas can trigger cross-reactive antibodies that may confound M. bovis serology requires further study.

Mycoplasma bovis Infections in Free-Ranging Pronghorn, Wyoming, USA

Mycoplasma bovis is 1 of several bacterial pathogens associated with pneumonia in cattle. Its role in pneumonia of free-ranging ungulates has not been established. Over a 3-month period in early 2019, »60 free-ranging pronghorn with signs of respiratory disease died in northeast Wyoming, USA. A consistent finding in submitted carcasses was severe fibrinosuppurative pleuropneumonia and detection of M. bovis by PCR and immunohistochemical analysis. Multilocus sequence typing of isolates from 4 animals revealed that all have a deletion in 1 of the target genes, adh-1. A retrospective survey by PCR and immunohistochemical analysis of paraffin-embedded lung from 20 pronghorn that died with and without pneumonia during 2007–2018 yielded negative results. These findings indicate that a distinct strain of M. bovis was associated with fatal pneumonia in this group of pronghorn.

Phylogeny of Mycoplasma bovis isolates from cattle and bison based on multi locus sequence typing and multiple-locus variable-number tandem repeats

Multiple outbreaks of Mycoplasma bovis (M. bovis) have been reported in North American bison (Bison bison) in Alberta, Manitoba, Saskatchewan, Nebraska, New Mexico, Montana, North Dakota, and Kansas. M. bovis is mainly spread through direct contact and disseminated via animal movements thus, reliable genotyping is crucial for epidemiological investigations. The present study describes the genotyping of sixty-one M. bovis strains from cattle and bison isolated from different provinces of Canada by multi locus sequence typing (MLST), and multiple-locus variable-number tandem repeat analysis (MLVA). The sixty M. bovis clinical isolates together with the reference strain PG45 were divided into ten sequence types by MLST. Three novel sequence types were identified. Two isolates, one from cattle and one from bison shared the same sequence type, whereas one strain had the same sequence type as PG45. The cattle isolates could be further subdivided in Clade A with two subclades and bison isolates were grouped in Clade B with two subclades. With the exception of one animal, isolates originating from the same animal had the same sequence type. The sixty-one isolates also formed three main clades with several subclades when analyzed by MLVA. A total of 20 VNTR (Variable number tandem repeats) types were distinguished, 8 in cattle and 12 in bison isolates. The results showed multiple sequence types and genotype populations of M. bovis in bison and cattle. The results may further help to understand the evolution of M. bovis and develop strain specific or sequence type diagnostic tools.

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.

The Suppression of Th1 Response by Inducing TGF-β1 From Regulatory T Cells in Bovine Mycoplasmosis

Regulatory T cells (Tregs) regulate immune responses and maintain host immune homeostasis. Tregs contribute to the disease progression of several chronic infections by oversuppressing immune responses via the secretion of immunosuppressive cytokines, such as transforming growth factor (TGF)-β and interleukin-10. In the present study, we examined the association of Tregs with Mycoplasma bovis infection, in which immunosuppression is frequently observed. Compared with uninfected cattle, the percentage of Tregs, CD4⁺CD25^highFoxp3⁺ T cells, was increased in M. bovis-infected cattle. Additionally, the plasma of M. bovis-infected cattle contained the high concentrations of TGF-β1, and M. bovis infection induced TGF-β1 production from bovine immune cells in in vitro cultures. Finally, we analyzed the immunosuppressive effects of TGF-β1 on bovine immune cells. Treatment with TGF-β1 significantly decreased the expression of CD69, an activation marker, in T cells, and Th1 cytokine production in vitro. These results suggest that the increase in Tregs and TGF-β1 secretion could be one of the immunosuppressive mechanisms and that lead to increased susceptibility to other infections in terms of exacerbation of disease during M. bovis infection.

Upregulation of PD-L1 Expression by Prostaglandin E2 and the Enhancement of IFN-γ by Anti-PD-L1 Antibody Combined With a COX-2 Inhibitor in Mycoplasma bovis Infection

Bovine mycoplasmosis caused by Mycoplasma bovis results in pneumonia and mastitis in cattle. We previously demonstrated that the programmed death 1 (PD-1)/PD-ligand 1 (PD-L1) pathway is involved in immune dysfunction during M. bovis infection and that prostaglandin E₂ (PGE₂) suppressed immune responses and upregulated PD-L1 expression in Johne's disease, a bacterial infection in cattle. In this study, we investigated the role of PGE₂ in immune dysfunction and the relationship between PGE₂ and the PD-1/PD-L1 pathway in M. bovis infection. In vitro stimulation with M. bovis upregulated the expressions of PGE₂ and PD-L1 presumably via Toll-like receptor 2 in bovine peripheral blood mononuclear cells (PBMCs). PGE₂ levels of peripheral blood in infected cattle were significantly increased compared with those in uninfected cattle. Remarkably, plasma PGE₂ levels were positively correlated with the proportions of PD-L1⁺ monocytes in M. bovis-infected cattle. Additionally, plasma PGE₂ production in infected cattle was negatively correlated with M. bovis-specific interferon (IFN)-γ production from PBMCs. These results suggest that PGE₂ could be one of the inducers of PD-L1 expression and could be involved in immunosuppression during M. bovis infection. In vitro blockade assays using anti-bovine PD-L1 antibody and a cyclooxygenase 2 inhibitor significantly upregulated the M. bovis-specific IFN-γ response. Our study findings might contribute to the development of novel therapeutic strategies for bovine mycoplasmosis that target PGE₂ and the PD-1/PD-L1 pathway.

Mycoplasma bovis arthritis and pneumonia in calves in Jordan: An emerging disease

Aim:

Clinical, microbiological, molecular, and pathological assays were undertaken to characterize an outbreak of increasingly reported signs of unresponsive arthritis and pneumonia of Mycoplasma bovis infection in young calves in Jordan.

Materials and Methods:

Clinical history of the affected bovine herd was investigated for the presence of respiratory and/or joint problems. Two calves with such history were clinically examined and necropsied. Representative tissues were sent for microbiological, molecular, and pathological examinations for M. bovis infection.

Results:

The outbreak started in a herd of 220 nursing calves, 2 months before the receiving of two calves for postmortem examination. Clinically, respiratory signs and infection of one or more joints dominated in the affected calves. The morbidity and case fatality rates were 27.27% and 61.7%, respectively. The left carpal joint was markedly swollen in both calves and exhibited necrofibrinous to granulomatous arthritis in varying degrees of severity. The anteroventral lung lobes in both calves were consistently affected and revealed multifocal to coalescing severe necrogranulomatous and fibrinopurulent bronchopneumonia. Microbiological and molecular findings confirmed the pathological examination. Furthermore, bovine viral diarrhea (BVD) was diagnosed in one calf by histopathology and polymerase chain reaction.

Conclusion:

This investigation reports the first outbreak of M. bovis infection in calves located in Jordan that could occur concurrently with BVD.

Relative virulence in bison and cattle of bison-associated genotypes of Mycoplasma bovis

Mycoplasma bovis, a frequent contributor to polymicrobial respiratory disease in cattle, has recently emerged as a major health problem in North American bison. Strong circumstantial evidence suggests it can be the sole pathogen causing disease manifestations in outbreaks of mortality in bison, but direct evidence is lacking. The goal of this study was to compare clinical signs and lesions in bison and cattle experimentally infected with field isolates of M. bovis recovered from bison. Bison (n = 7) and cattle (n = 6), seronegative for anti-M. bovis IgG, were exposed intranasally to M. bovis and necropsied 4-6 weeks later. Blood and nasal swabs were collected on day 0 (before exposure), day 11 and at necropsy. Samples of lung, lymph node, liver and spleen were also collected at necropsy. The only clinical sign observed was an elevation in the core body temperature of bison during the first few weeks post-exposure. Grossly visible lesions were apparent at necropsy in the lungs of five bison and the lymph node of one bison, while none were evident in cattle. Histologic evaluation revealed moderate to severe pulmonary lesions in four bison but none in cattle. M. bovis was recovered from tissues demonstrating gross lesions and from the lymph nodes of one additional bison and two cattle. All animals seroconverted by the time of necropsy. These data provide the first direct evidence that M. bovis can be a sole or primary cause of respiratory disease in healthy bison, although the isolates used were unable to cause disease in healthy cattle.

Observations of mortality in farmed bison in the Canadian prairies: 2103 - 2016

The present study is a continuation of a previous mortality study on Saskatchewan bison farms with special emphasis on Malignant Catarrhal Fever. The updated objective of the study was to estimate the most common causes of mortality in farmed bison herds in Western Canada. Results were compared to the previous Saskatchewan study to assess the similarities and differences in the etiology associated with farmed bison deaths across the Prairie Provinces of Canada. The most common cause of death was respiratory disease associated with Mycoplasma bovis, although this was restricted to Alberta and Saskatchewan farm locations. This was in contrast to the previous Saskatchewan based study which did not identify any deaths involving this pathogen. An updated overall assessment of the risks of Malignant Catarrhal Fever in farmed bison at various proximities to sheep operations further confirmed the low risk of occurrence on farms within a 1 km boundary fence distance.

Mistaken identity of an open reading frame proposed for PCR-based identification of Mycoplasma bovis and the effect of polymorphisms and insertions on assay performance

Mycoplasma bovis is an important cause of disease in cattle and bison. Because the bacterium requires specialized growth conditions, many diagnostic laboratories routinely use PCR to replace or complement conventional isolation and identification methods. A frequently used target of such assays is the uvrC gene, which has been shown to be highly conserved among isolates. We discovered that a previously described PCR putatively targeting the uvrC gene amplifies a fragment from an adjacent gene predicted to encode a lipoprotein. Comparison of the lipoprotein gene sequence from 211 isolates revealed several single nucleotide polymorphisms, 1 of which falls within a primer-binding sequence. Additionally, 3 isolates from this group were found to have a 1,658-bp transposase gene insertion within the amplified region that leads to a false-negative result. The insertion was not detected in a further 164 isolates. We found no evidence that the nucleotide substitution within the primer-binding region affects the assay sensitivity, performance, or limit of detection. Nonetheless, laboratories utilizing this method for identification of M. bovis should be aware that the region amplified may be prone to nucleotide substitutions and/or insertions relative to the sequence used for its design and that occasional false-negative results may be obtained.

A serologic survey of Mycoplasma spp. in farmed bison ( Bison bison) herds in western Canada

Mycoplasma bovis is emerging as an important pathogen of farmed bison in North America and is associated with high morbidity and mortality in affected herds. We developed an in-house ELISA to detect antibodies against Mycoplasma spp. in bison sera. The aims of the study were to estimate the seroprevalence against Mycoplasma spp. in bison herds with or without past history of M. bovis-associated disease, and to determine potential risk factors for seropositivity to Mycoplasma spp. in farmed bison in western Canada. A total of 858 serum samples were collected from bison >1 y of age from 19 bison herds. The individual and herd-level seroprevalence of Mycoplasma spp. was 12% and 79%, respectively. The proportion of seropositive animals was 0-41% and 0-9% for herds with or without a history of M. bovis-associated disease, respectively. Mycoplasma spp. appear to be widespread in bison in Manitoba, Saskatchewan, and Alberta. Eight of 11 herds with no history of M. bovis-associated disease were seropositive for Mycoplasma spp., which suggests that bison can be subclinically infected with Mycoplasma spp., or that infection may be underdiagnosed. Although not specific to M. bovis, the in-house ELISA developed to detect antibodies against Mycoplasma spp. may prove to be a valuable herd-level screening tool, providing insight needed for the development of appropriate prevention and control measures for Mycoplasma-related disease in bison herds.

In vitro antimicrobial susceptibility of Mycoplasma bovis clinical isolates recovered from bison (Bison bison)

Mycoplasma bovis is a pathogen globally affecting cattle and bison herds, causing pneumonia, arthritis, mastitis, abortions, and other symptoms, leading to huge economic losses. Many studies have been done regarding the antimicrobial susceptibility of M. bovis isolated from cattle, but no such study is available for isolates recovered from bison. For the first time, in vitro susceptibilities of 40 M. bovis clinical isolates collected from bison herds in Canada are reported here. Minimal inhibitory concentration (MIC) values were determined using Sensititre® plates. The most effective MIC50 and MIC90 were for spectinomycin (1 and >64 μg/mL), tiamulin (1 and >32 μg/mL), and tulathromycin (16 and 64 μg/mL), whereas tetracyclines, fluoroquinolones, and florfenicol failed to inhibit growth of M. bovis bison isolates. Isolates were nonsusceptible to tetracyclines (100%), fluoroquinolones (97.5%), and tilmicosin (100%), whereas the highest susceptibility of bison clinical isolates was seen with spectinomycin (95%) and tulathromycin (67.5%). Two lung isolates (Mb283 and 348) were found resistant to both spectinomycin and tulathromycin. These results show a marked difference in antimicrobial susceptibility of bison isolates as compared with previously reported and laboratory reference cattle isolates, emphasizing the necessity of testing antimicrobial susceptibility of M. bovis bison isolates and to generate better therapeutic regime for improved recovery chances for infected bison herds across North America.

Mycoplasma bovis isolates recovered from cattle and bison (Bison bison) show differential in vitro effects on PBMC proliferation, alveolar macrophage apoptosis and invasion of epithelial and immune cells

In the last few years, several outbreaks of pneumonia, systemically disseminated infection, and high mortality associated with Mycoplasma bovis (M. bovis) in North American bison (Bison bison) have been reported in Alberta, Manitoba, Saskatchewan, Nebraska, New Mexico, Montana, North Dakota, and Kansas. M. bovis causes Chronic Pneumonia and Polyarthritis Syndrome (CPPS) in young, stressed calves in intensively-managed feedlots. M. bovis is not classified as a primary pathogen in cattle, but in bison it appears to be a primary causative agent with rapid progression of disease with fatal outcomes and an average 20% mature herd mortality. Thus, there is a possibility that M. bovis isolates from cattle and bison differ in their pathogenicity. Hence, we decided to compare selected cattle isolates to several bison isolates obtained from clinical cases. We show differences in modulation of PBMC proliferation, invasion of trachea and lung epithelial cells, along with modulation of apoptosis and survival in alveolar macrophages. We concluded that some bison isolates showed less inhibition of cattle and bison PBMC proliferation, were not able to suppress alveolar macrophage apoptosis as efficiently as cattle isolates, and were more or less invasive than the cattle isolate in various cells. These findings provide evidence about the differential properties of M. bovis isolated from the two species and has helped in the selection of bison isolates for genomic sequencing.

A serological and molecular study on the occurrence of mycoplasmas in European bison (Bison bonasus) from two areas of Eastern Poland

European bison (Bison bonasus) from two different areas of Eastern Poland showing gross pathology possibly associated with mycoplasma infections were tested for ruminant Mycoplasma species using serological and molecular methods. Fifty-five samples, blood or tissue were collected from 28 animals during 2013-2014. Six sera were positive for Mycoplasma bovis. The ELISA and complement fixation test for Mycoplasma mycoides subsp. mycoides gave a few weak reactions, but were negative by immunoblotting and molecular methods.

Pharmacokinetics of tulathromycin after subcutaneous injection in North American bison (Bison bison)

Tulathromycin is approved for the treatment of respiratory disease in cattle and swine. It is intended for long-acting, single-dose injection therapy (Draxxin), making it particularly desirable for use in bison due to the difficulty in handling and ease of creating stress in these animals. The pharmacokinetic properties of tulathromycin in bison were investigated. Ten wood bison received a single 2.5 mg/kg subcutaneous injection of Draxxin. Serum concentrations were measured by liquid chromatography-mass spectrometry (LC-MS) detection. Tulathromycin demonstrated early maximal serum concentrations, extensive distribution, and slow elimination characteristics. The mean maximum serum concentration (Cmax) was 195 ng/mL at 1.04 h (tmax) postinjection. The mean area under the serum concentration-time curve, extrapolated to infinity (AUC0-inf ), was 9341 ng · h/mL. The mean apparent volume of distribution (Vd /F) and clearance (Cls/F) was 111 L/kg and 0.4 L/h/kg, respectively, and the mean half-life (t1/2) was 214 h (8.9 days). Compared to values for cattle, Cmax and AUC0-inf were lower in bison, while the Vd /F was larger and the t1/2 longer. Tissue distribution and clinical efficacy studies in bison are needed to confirm the purported extensive distribution of tulathromycin into lung tissue and to determine whether a 2.5 mg/kg subcutaneous dosage is adequate for bison.

Serological studies to determine the occurrence of Johne’s disease and mycoplasma infection in the Northern-East Polish population of European bison (Bison bonasus)

A serological study of twenty three European bison (Bison bonasus) derived from Northern-East Poland for the seroprevalence of Mycobacterium avium subsp. paratuberculosis, Mycoplasma bovis, Mycoplasma mycoides subsp. mycoides SC, Mycoplasma agalactiae and Mycoplasma capricolum subsp. capripneumoniae was conducted. Only specific antibodies to M. bovis were detected in two animals (8.7%) which were connected with the clinical signs and macroscopic anatomopathological lesions.

Multilocus sequence typing of Mycoplasma bovis reveals host-specific genotypes in cattle versus bison

Mycoplasma bovis is a primary agent of mastitis, pneumonia and arthritis in cattle and the bacterium most frequently isolated from the polymicrobial syndrome known as bovine respiratory disease complex. Recently, M. bovis has emerged as a significant health problem in bison, causing necrotic pharyngitis, pneumonia, dystocia and abortion. Whether isolates from cattle and bison comprise genetically distinct populations is unknown. This study describes the development of a highly discriminatory multilocus sequencing typing (MLST) method for M. bovis and its use to investigate the population structure of the bacterium. Genome sequences from six M. bovis isolates were used for selection of gene targets. Seven of 44 housekeeping genes initially evaluated were selected as targets on the basis of sequence variability and distribution within the genome. For each gene target sequence, four to seven alleles could be distinguished that collectively define 32 sequence types (STs) from a collection of 94 cattle isolates and 42 bison isolates. A phylogeny based on concatenated target gene sequences of each isolate revealed that bison isolates are genetically distinct from strains that infect cattle, suggesting recent disease outbreaks in bison may be due to the emergence of unique genetic variants. No correlation was found between ST and disease presentation or geographic origin. MLST data reported here were used to populate a newly created and publicly available, curated database to which researchers can contribute. The MLST scheme and database provide novel tools for exploring the population structure of M. bovis and tracking the evolution and spread of strains.

Mycoplasma ovipneumoniae--a primary cause of severe pneumonia epizootics in the Norwegian Muskox (Ovibos moschatus) population

The Norwegian muskox (Ovibos moschatus) population lives on the high mountain plateau of Dovre and originates from animals introduced from Greenland. In the late summers of 2006 and 2012, severe outbreaks of pneumonia with mortality rates of 25-30% occurred. During the 2012 epidemic high quality samples from culled sick animals were obtained for microbiological and pathological examinations. High throughput sequencing (pyrosequencing) of pneumonic lung tissue revealed high concentrations of Mycoplasma ovipneumoniae in all six animals examined by this method and Pasteurella multocida subsp. multocida in four animals, whereas no virus sequences could be identified. Mycoplasma ovipneumoniae and P. multocida multocida were also isolated by culture. Using real time PCR on lung swabs, M. ovipneumoniae was detected in all of the 19 pneumonic lungs examined. Gross pathological examination revealed heavy consolidations primarily in the cranial parts of the lungs and it also identified one case of otitis media. Histologically, lung lesions were characterized as acute to subacute mixed exudative and moderately proliferative bronchoalveolar pneumonia. Immunohistochemical (IHC) examination revealed high load of M. ovipneumoniae antigens within lung lesions, with particularly intensive staining in the neutrophils. Similar IHC finding were observed in archived lung tissue blocks from animals examined during the 2006 epidemic. An M. ovipneumoniae specific ELISA was applied on bio-banked muskox sera from stray muskoxen killed in the period 2004-2013 and sick muskoxen culled, as well as sera from wild reindeer (Rangifer tarandus tarandus) on Dovre and muskoxen from Greenland. Serology and mycoplasma culturing was also carried out on sheep that had been on pasture in the muskox area during the outbreak in 2012. Our findings indicated separate introductions of M. ovipneumoniae infection in 2006 and 2012 from infected co-grazing sheep. Salt licks shared by the two species were a possible route of transmitting infection.

Systemic mycoplasmosis with dystocia and abortion in a North American bison (Bison bison) herd

The current study describes a fatal Mycoplasma bovis infection in a North American bison ( Bison bison) cow and her aborted fetus in a herd suffering unusual mortality associated with dystocia and abortion. Postmortem evaluation of the subject case found severe caseonecrotic bronchopneumonia, chronic fibrinous pleuritis and pulmonary sequestra, foci of caseous necrosis in the kidneys, and necrotizing endometritis and placentitis. Histologic findings in the maternal tissues include endometrial and placental necrotizing vasculitis and changes in the lung similar to those previously described for M. bovis–associated pneumonia in feedlot bison. Gross and microscopic lesions were not observed in the fetus. Maternal lung, uterus, kidney, and placenta as well as fetal lung and kidney were positive for M. bovis by polymerase chain reaction (PCR) as were the Mycoplasma-like colonies cultured from these tissues. The presence of M. bovis in maternal and fetal tissues was further demonstrated using nucleic acid extracts in a pan- Mycoplasma SYBR Green PCR assay targeting the 16S-23S ribosomal RNA spacer region with post-PCR dissociation curve analysis and sequencing of the resulting amplicons. Immunohistochemistry (IHC) testing on maternal lung and uterine caruncle was strongly positive for M. bovis antigen. A variety of methods, including culture, PCR, and IHC, failed to identify other bacterial or viral pathogens in any of the tissues evaluated. These data are the first to implicate M. bovis as a cause of placentitis and abortion in bison.

Evaluation of enzyme-linked immunosorbent assays for detection of Mycoplasma bovis-specific antibody in bison sera

Mycoplasma bovis has recently emerged as a significant and costly infectious disease problem in bison. A method for the detection of M. bovis-specific serum antibodies is needed in order to establish prevalence and transmission patterns. Enzyme-linked immunosorbent assays (ELISAs) validated for the detection of M. bovis-specific serum IgG in cattle are commercially available, but their suitability for bison sera has not been determined. A collection of bison sera, most from animals with a known history of infection or vaccination with M. bovis, was tested for M. bovis-specific IgG using commercially available kits as well as an in-house ELISA in which either cattle or bison M. bovis isolates were used as a source of antigen. Comparison of the results demonstrates that ELISAs optimized for cattle sera may not be optimal for the identification of bison seropositive for M. bovis, particularly those with low to moderate antibody levels. The reagent used for the detection of bison IgG and the source of the antigen affect the sensitivity of the assay. Optimal performance was obtained when the capture antigen was derived from bison isolates rather than cattle isolates and when a protein G conjugate rather than an anti-bovine IgG conjugate was used for the detection of bison IgG.

Necrotic pharyngitis associated with Mycoplasma bovis infections in American bison (Bison bison)

Mycoplasma bovis has emerged as a significant and costly infectious disease problem in bison, generally presenting as severe, caseonecrotic pneumonia. Three diagnostic cases in which M. bovis is associated with necrotic pharyngitis in bison are described in the current study. The bacterium was isolated from lesions of the pharynx or lung of 3 American bison ( Bison bison), at 2 different locations in the upper Midwestern United States, with severe, necrotic pharyngeal abscesses. Chronic caseonecrotic inflammation typical of M. bovis infection in bovines was observed microscopically in the pharynxes of affected bison. A mixed population of bacteria was recovered from the pharyngeal lesions, and Trueperella pyogenes, a frequent secondary pathogen in ruminant respiratory disease, was consistently isolated from the affected animals. Distinctive histopathological features of the pharyngeal lesions favor causation by M. bovis, although a role for T. pyogenes in the clinical presentation cannot be excluded. Veterinarians and producers working with bison should be aware that M. bovis may be associated with pharyngitis in bison.