Cellular and cytokine responses in the granulomas of asymptomatic cattle naturally infected with mycobacterium bovis in Ethiopia

Begna Tulu, Henny M. Martineau, Aboma Zewude, Fekadu Desta, David A. Jolliffe, Markos Abebe, Taye Tolera Balcha, Mulugeta Belay, Adrian R. Martineau, Gobena Ameni

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Cell (CD3+ T cell and CD68+ macrophages), cytokine (interferon gamma-positive [IFN-γ+] and tumor necrosis factor alpha-positive [TNF-α+]), and effector molecule (inducible nitric oxide synthase-positive [iNOS+]) responses were evaluated in the lymph nodes and tissues of cattle naturally infected with Mycobacterium bovis. Detailed postmortem and immunohistochemical examinations of lesions were performed on 16 cows that were positive by the single intradermal cervical comparative tuberculin (SICCT) test and that were identified from dairy farms located around the city of Addis Ababa, Ethiopia. The severity of the gross lesion was significantly higher (P = 0.003) in M. bovis culture-positive cows (n = 12) than in culture-negative cows (n = 4). Immunohistochemical techniques showed that in culture-positive cows, the mean immunolabeling fraction of CD3+ T cells decreased as the stage of granuloma increased from stage I to stage IV (P < 0.001). In contrast, the CD68+ macrophage, IFN-γ+, TNF-α+, and iNOS+ immunolabeling fractions increased from stage I to stage IV (P < 0.001). In the early stages, culture-negative cows showed a significantly higher fraction of CD68+ macrophage (P = 0.03) and iNOS+ (P = 0.007) immunolabeling fractions than culture-positive cows. Similarly, at advanced granuloma stages, culture-negative cows demonstrated significantly higher mean proportions of CD3+ T cells (P < 0.001) than culture-positive cows. Thus, this study demonstrates that, following natural infection of cows with M. bovis, as the stage of granuloma increases from stage I to stage IV, the immunolabeling fraction of CD3+ cells decreases, while the CD68+ macrophage, IFN-γ+, TNF-α+, and iNOS+ immunolabeling fractions increases.

Original languageEnglish
Article numbere00507-20
JournalInfection and Immunity
Volume88
Issue number12
DOIs
Publication statusPublished - Dec 2020

Keywords

  • Asymptomatic cows
  • Granuloma
  • Granulomatous lesion
  • Immune response
  • Immune response
  • Immunohistochemistry
  • Mycobacterium bovis
  • Natural infection

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

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