Location: Animal Disease Research Unit
Title: Differential immunological responses of adult domestic and Bighorn sheep to inoculation with mycoplasma ovipneumoniae type strain Y98Author
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MADSEN-BOUTERSE, SALLY - Washington State University |
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Herndon, David |
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Grossman, Paige |
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RIVOLTA, ALEJANDRA - Washington State University |
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FRY, LINDSAY - Former ARS Employee |
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MURDOCH, BRENDA - University Of Idaho |
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Piel, Lindsay |
Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/9/2024 Publication Date: 12/21/2024 Citation: Madsen-Bouterse, S.A., Herndon, D.R., Grossman, P.C., Rivolta, A.A., Fry, L.M., Murdoch, B.M., Piel, L.M. 2024. Differential immunological responses of adult domestic and Bighorn sheep to inoculation with mycoplasma ovipneumoniae type strain Y98. Microorganisms. https://doi.org/10.3390/microorganisms12122658. DOI: https://doi.org/10.3390/microorganisms12122658 Interpretive Summary: Bighorn sheep (BHS) and domestic sheep (DS) respond differently to exposure of upper respiratory pathogens. Understanding these differences requires knowledge of the different immunological states and responses to specific pathogens. This study reports some general differences in the immune system between these two species prior to inoculation with a pathogen known to be associated with pneumonia. At a resting state, BHS were found to have higher amounts of the innate cell surface marker CD14 and the anti-inflammatory cytokine IL-36RA. DS have higher amounts of integrin markers (CD18, CD11a, and CD11b), CD172a and CD16 along with an increased amount of the typically pro-inflammatory cytokine TNF alpha. Following inoculation with a single strain of Mycoplasma ovipneumoniae, DS did not exhibit respiratory symptoms and immunological markers remained largely unchanged. In contrast, BHS exhibited mild respiratory symptoms and demonstrated alterations in several immune markers including CD172a, CD14, CD11b and cytokines IL-36RA and IP-10. Collectively, these results suggest that BHS and DS have different resting immune states and that this difference may be at least partially responsible for the altered disease presentation following M. ovipneumoniae inoculation. Technical Abstract: Bighorn sheep (BHS) populations have been reported to experience high levels of morbidity and mortality following infection with Mycoplasma ovipneumoniae. This contrasts with what is exhibited in domestic sheep (DS), which tend to present with subclinical disease. The immunologic mechanisms underlying this contrasting difference in susceptibility remain poorly understood. Fundamental to understanding this difference is the knowledge of baseline immune status and post-infection immune responses of both species. The present study identifies differences in leukocyte phenotypes between adult BHS and DS before and after intranasal inoculation with Mycoplasma ovipneumoniae. Prior to inoculation, not only were BHS confirmed to have a higher abundance of leukocyte CD14 but higher serum concentrations of IL-36RA were also observed. In contrast, DS had a higher leukocyte abundance of CD16 in addition to previously observed integrin markers (CD18, CD11a, and CD11b) and CD172a; greater serum TNF-a concentrations were also observed in DS. Within 15 days of inoculation, BHS displayed signs of mild respiratory disease, and M. ovipneumoniae DNA was detected on nasal swabs by quantitative PCR; meanwhile, DS exhibited few to no clinical signs and had levels of M. ovipneumoniae DNA below the threshold of detection. Immunologic markers investigated in this study remained relatively consistent pre- and post-inoculation in DS, while BHS demonstrated changes in peripheral neutrophil and blood mononuclear cell expression of CD172a and CD14. Circulating serum IL-36RA decreased and IP-10 increased within BHS. These findings highlight significant differences in cellular immunity between BHS and DS raised and housed under similar conditions, prior to and following infection with M. ovipneumoniae. |