Differential Cell Composition and Cytokine Expression Within Lymph Node Granulomas from BCG-Vaccinated and Non-vaccinated Cattle Experimentally Infected with Mycobacterium bovis

F. J. Salguero*, S. Gibson, W. Garcia-Jimenez, J. Gough, T. S. Strickland, H. M. Vordermeier, B. Villarreal-Ramos

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (SciVal)

Abstract

Cattle vaccination against bovine tuberculosis (bTB) has been proposed as a supplementary method to help control the incidences of this disease. Bacillus Calmette–Guérin (BCG) is currently the only viable candidate vaccine for immunization of cattle against bTB, caused by Mycobacterium bovis (M. bovis). In an attempt to characterize the differences in the immune response following M. bovis infection between BCG-vaccinated and non-vaccinated animals, a combination of gross pathology, histopathology and immunohistochemical (IHC) analyses was used. BCG vaccination was found to significantly reduce the number of gross and microscopic lesions present within the lungs and lymph nodes. Additionally, the microscopically visible bacterial load of stages III and IV granulomas was reduced. IHC using cell surface markers revealed the number of CD68+ (macrophages), CD3+ (T lymphocytes) and WC1+ cells (γδ T cells) to be significantly reduced in lymph node granulomas of BCG-vaccinated animals, when compared to non-vaccinated animals. B lymphocytes (CD79a+) were significantly increased in BCG-vaccinated cattle for granulomas at stages II, III and IV. IHC staining for iNOS showed a higher expression in granulomas from BCG-vaccinated animals compared to non-vaccinated animals for all stages, being statistically significant in stages I and IV. TGFβ expression decreased alongside the granuloma development in non-vaccinated animals, whereas BCG-vaccinated animals showed a slight increase alongside lesion progression. IHC analysis of the cytokines IFN-γ and TNF-α demonstrated significantly increased expression within the lymph node granulomas of BCG-vaccinated cattle. This is suggestive of a protective role for IFN-γ and TNF-α in response to M. bovis infection. Findings shown in this study suggest that the use of BCG vaccine can reduce the number and severity of lesions, induce a different phenotypic response and increase the local expression of key cytokines related to protection.

Original languageEnglish
Pages (from-to)1734-1749
Number of pages16
JournalTransboundary and Emerging Diseases
Volume64
Issue number6
Early online date11 Sept 2016
DOIs
Publication statusPublished - 07 Nov 2017

Keywords

  • BCG
  • bovine tuberculosis
  • cytokine
  • immune response
  • immunohistochemistry

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