Cell mediated immune response in goats after experimental challenge with the virulent Brucella melitensis strain 16M and the reduced virulence strain Rev. 1

The objective of the present study was to evaluate the caprine immune response over the course of infection with virulent B. melitensis strain 16 M and reduced virulence vaccine strain Rev. 1. Pregnant goats were infected at 11–14 weeks of gestation with 8 × 106 or 8 × 107 CFU of B. melitensis. Changes in granulocyte, monocyte, and mononuclear cell numbers were monitored by flow cytometry. Proliferative and functional responses of CD4+ T cells and WC1+ γδ T cells were also studied. B. melitensis 16 M infection triggered a pro-inflammatory response characterized by increased numbers of granulocytes, monocytes, and lymphocytes. The relative lymphocytosis was comprised of increases in CD4+ but not WC1+ T cell types in most animals. Little proliferative response was observed in Rev. 1-infected goats. Analysis of lymphocyte function suggested a degree of potential CD4+ T cell anergy, with low levels of CD25 expression and unresponsiveness to mitogen stimulation noted post-infection. The components of the protective response elicited by the Rev. 1 vaccine strain remain undefined. The study suggests a potential WC1+ γδ T cell mediated response, with high percentages of γδ T cells found to produce IFN-γ at various time points over the course of Brucella infection.
Source: Veterinary Immunology and Immunopathology - Category: Veterinary Research Source Type: research