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

Authors: Register, Karen; PARKER, MARGARET - Animal And Plant Health Inspection Service (APHIS); PATYK, KELLY - Animal And Plant Health Inspection Service (APHIS); SWEENEY, STEVEN - Animal And Plant Health Inspection Service (APHIS); Boatwright, Jr, William; JONES, LEE - Us Fish And Wildlife Service; WOODBURY, MURRAY - University Of Saskatchewan; HUNTER, DAVID - Turner Enterprises, Inc; TREANOR, JOHN - Yellowstone Heritage And Research Center; KOHR, MARSHALL - Animal Medical Center Of Wyoming, Llc; HAMILTON, ROBERT - The Nature Conservancy; SHURY, TODD - Saskatoon Research Center; NOL, PAULINE - Animal And Plant Health Inspection Service (APHIS)

Submitted to: BMC Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2020
Publication Date: 1/7/2021
Publication URL: https://handle.nal.usda.gov/10113/7228923
Citation: Register, K.B., Parker, M., Patyk, K.A., Sweeney, S.J., Boatwright Jr, W.D., Jones, L.C., Woodbury, M., Hunter, D., Treanor, J., Kohr, M., Hamilton, R., Shury, T., Nol, P. 2021. Serological evidence for historical and present-day exposure of North American bison to Mycoplasma bovis. BMC Veterinary Research. 17. Article 18. https://doi.org/10.1186/s12917-020-02717-5.
DOI: https://doi.org/10.1186/s12917-020-02717-5

Interpretive Summary: 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 can carry M. bovis in the respiratory tract without any outward signs and when M. bovis infected bison for the first time is not known. To investigate these questions we used a commercially available kit that detects antibodies to M. bovis to test 3295 blood samples collected between 1984 and 2019 from bison in the United States and Canada. We identified positive bison from as long ago as the late 1980’s. The average prevalence of positive bison 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. The prevalence of positive bison 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, the frequency of positive bison in the United States since the year 2000 dropped significantly as compared to the years 1985-1999. In Canada the trend is reversed, with prevalence increasing significantly since the year 2000. The prevalence of M. bovis-specific antibodies in the blood of free-ranging bison does not differ significantly from the prevalence among more intensively managed, more highly stressed bison, regardless of the era in which they were sampled. However, among intensively raised Canadian bison the frequency of antibody-positive animals has nearly doubled since the year 2000 and the average level of antibodies detected also rose significantly. 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.

Technical Abstract: 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 between 1984 and 2019 from bison in the United States and Canada. Results. We identified moderately to strongly seropositive bison from as long ago as the late 1980’s. 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 obtained 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.