Mycoplasma bovis infections in free-ranging pronghorn, Wyoming, USA

Authors: MALMBERG, JENNIFER - University Of Wyoming; O'TOOLE, DONAL - University Of Wyoming; CREEKMORE, TERRY - Wyoming Department Of Game & Fish; PECKHAM, ERICA - Wyoming Department Of Game & Fish; KILLION, HALLY - Wyoming State Veterinary Laboratory; VANCE, MADISON - Wyoming State Veterinary Laboratory; ASHLEY, REBECCA - Wyoming State Veterinary Laboratory; JOHNSON, MARGUERITE - University Of Wyoming; ANDERSON, CHRISTOPHER - University Of Wyoming; VASQUEZ, MARCE - Wyoming State Veterinary Laboratory; SANDIDGE, DOUGLAS - University Of Wyoming; MILDENBERGER, JIM - Public Health Laboratory; HULL, NOAH - Public Health Laboratory; BRADWAY, DAN - Washington State University; CORNISH, TODD - University Of Wyoming; Register, Karen; SONDGEROTH, KERRY - University Of Wyoming

Submitted to: Emerging Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2020
Publication Date: 10/29/2020
Citation: Malmberg, J., O'Toole, D., Creekmore, T., Peckham, E., Killion, H., Vance, M., Ashley, R., Johnson, M., Anderson, C., Vasquez, M., Sandidge, D., Mildenberger, J., Hull, N., Bradway, D., Cornish, T., Register, K.B., Sondgeroth, K.S. 2020. Mycoplasma bovis infections in free-ranging pronghorn, Wyoming, USA. Emerging Infectious Diseases. 26(12):2807-2814. https://doi.org/10.3201/eid2612.191375.
DOI: https://doi.org/10.3201/eid2612.191375

Interpretive Summary: Mycoplasma bovis (M. bovis) is one of several bacterial pathogens associated with respiratory disease in cattle. It additionally causes disease in North American bison but is not known to be a disease-causing agent in other free-ranging, hooved mammals. During February through April of 2019, approximately 60 pronghorn died in northeastern Wyoming with signs of respiratory disease. A consistent finding from carcasses submitted to the Wyoming State Veterinary Diagnostic Laboratory was severe pneumonia and detection of M. bovis. Isolates of M. bovis from pronghorn were compared to those from bison and cattle using multilocus sequence typing (MLST), a method in which the DNA sequences of seven, specially selected genes are compared among all isolates being evaluated. MLST analysis revealed that all pronghorn isolates are missing one of these genes and that the combined DNA sequence from the remaining six genes has not so far been found in any other isolate of M. bovis. A missing MLST gene is an unusual finding, since the genes used for this type of analysis are considered to be "housekeeping" genes that are critically important for maintaining basic cell function. A retrospective survey of lung tissue from 20 additional pronghorn that died between 2007 and 2018, including 13 with pneumonia, did not reveal M. bovis in any sample. Together, these findings indicate the existence of a distinct strain of M. bovis that is associated with severe pneumonia and high mortality in pronghorn.

Technical Abstract: Mycoplasma bovis (M. bovis) is one of several bacterial pathogens associated with bovine respiratory disease in cattle, but its role in pneumonia of free-ranging ungulates has not been established. During February through April of 2019, approximately 60 pronghorn died in northeastern Wyoming with signs of respiratory disease. A consistent finding from carcasses submitted to the Wyoming State Veterinary Diagnostic Laboratory was severe fibrinosuppurative pleuropneumonia and detection of M. bovis by PCR and IHC. Isolates were grown in culture for additional characterization by whole genome sequencing. Multilocus sequence typing revealed a deletion of the adh-1 gene in all isolates. A retrospective survey of paraffin-embedded lung from pronghorn that died with and without pneumonia (2007-2018, N equal 20) was performed, however M. bovis was not detected by PCR or IHC. Together, findings indicate the existence of a distinct strain of M. bovis that is associated with severe pneumonia and high mortality in pronghorn. Mycoplasma bovis (M. bovis) is one of several bacterial pathogens associated with bovine respiratory disease in cattle, but its role in pneumonia of free-ranging ungulates has not been established. During February through April of 2019, approximately 60 pronghorn died in northeastern Wyoming with signs of respiratory disease. A consistent finding from carcasses submitted to the Wyoming State Veterinary Diagnostic Laboratory was severe fibrinosuppurative pleuropneumonia and detection of M. bovis by PCR and IHC. Isolates were grown in culture for additional characterization by whole genome sequencing. Multilocus sequence typing revealed a deletion of the adh-1 gene in all isolates. A retrospective survey of paraffin-embedded lung from pronghorn that died with and without pneumonia (2007-2018, N equal 20) was performed, however M. bovis was not detected by PCR or IHC. Together, findings indicate the existence of a distinct strain of M. bovis that is associated with severe pneumonia and high mortality in pronghorn.