P009 Identification of cytolytic B-T constructs of Y. pestis through evaluation of IFN and perforin secretion
Introduction Y. pestis can replicate within the cells during initial stages of infection in vivo. Cell-mediated immunity to Y. pestis is important for vaccine-mediated protection against plague, however, the exact nature and role of CMI in protection is not clear, probably it could be through the activation of CD4+ cells. Understanding the immune response generated by epitopes recognized by CD4+ and CD8+ T cells is important for the development of safe and effective vaccines designed to promote protective cellular immunity. Methods In the present study, the secretion of IFN-γ and IL-4 by splenocytes, stimulated by different constructs of B and T cell epitopes of F1 and V antigens, was measured by ELISpot assay. We also measured perforin and IFN-γ expression as a function of cell mediated immunity by flow cytometry. Results These B–T constructs of F1 and V antigens produced a high number of IFN-γ secreting cells compared to native antigen and a low number of IL-4 secreting cells. Furthermore, we observed a significantly high percent-age of CD4+ IFN-γ+ cells compared to CD8+ IFN-γ+ cells as well as a significantly high percentage of CD4+ perforin cells as compared to CD8+ perforin cells. Conclusion Thus, the study highlights the importance of Th1 cytokine and existence of high proportion of CD4+ T cells probably contributing protection in the host. This study proposes a new perspective for the development of vaccination strategies for Y. pestis that triggers T cell immune response.