Evaluation of granulysin and perforin as candidate biomarkers for protection following vaccination with mycobacterium bovis BCG or M. bovisΔRD1

Summary The development of improved vaccines against tuberculosis (TB) is directly linked to the investigation of new and better correlates of protection after vaccination against TB. Cloning and characterization of bovine homologues of the antimicrobial protein granulysin (Bo-lysin) and perforin by our group could be used as potential biomarkers for TB vaccination efficacy. In the present study, we examined the kinetics of granulysin, perforin, IFNγ and Fas-L responses to Mycobacterium bovis purified protein derivative (PPD) stimulation by peripheral blood mononuclear cells from M. bovisΔRD1-, BCG- and non-vaccinated cattle. Gene expression profiles following PPD stimulation showed significant increases in transcripts for granulysin and IFNγ in both CD4⁺ and CD8⁺ T cells in BCG-vaccinated as compared with non-vaccinated animals. Perforin and IFNγ examined by flow cytometry, showed a difference of 1-2% more PPD-specific cells in BCG-vaccinated than non-vaccinated animals. In the vaccine trial, granulysin and perforin were significantly increased in both vaccine groups as compared with control after vaccination and challenge. IFNγ expression was increased only after vaccination and secretion was higher in the control, non-protected group as compared with both vaccine groups demonstrating no correlation with protection upon vaccination. In summary, results shown here provide evidence that granulysin and perforin are prospective candidates as biomarkers of protection after vaccination against TB.