Search

Abstract: Dendritic cell antigen targeting primes robust immune responses in mouse models. Optimizing this immunization strategy in the actual hosts that require protection will advance development of efficacious contemporary vaccines. In a proof-of-concept study, we tested the immunogenicity of a single, low dose of a novel multi-component DNA construct expressing a CD205-targeted antigen fused to a CD40L minimal functional domain for linked DC activation. The DNA construct was formulated with DNA-encoded Flt3L and GM-CSF for DC recruitment and the formulation was evaluated in MHC class II-matched calves. Immunization of the calves with the CD205 antigen-targeting construct mixed with the cytokine constructs induced significant IFN-γ-secreting CD4+ T-cells, CD4+ T-cell proliferation, and antibody responses detectable within one week post-immunization. CD205 antigen-targeting significantly expanded IFN-γ-secreting CD4+ T-cells, CD4+ T-cell proliferation, and IgG antibody responses three weeks post-immunization. Nineteen weeks post-priming, the IFN-γ-secreting CD4+ T-cells, CD4+ T-cell proliferation, and the IgG titers were waning, but they remained significant. Following boosting at nineteen weeks post-immunization, the immune responses primed by the CD205-targeted antigen underwent rapid recall and the mean response tripled within one week post-boost. Comparative analysis of the immune responses observed one week post-priming versus the responses detected one week post-boost revealed that the average number of the IFN-γ-secreting CD4+ T-cells observed in the calves immunized with the CD205 antigen targeting construct increased five-fold, the mean CD4+ T-cell proliferation increased three-fold, whereas the mean IgG antibody titer increased two hundred-fold. These promising outcomes support testing the protective efficacy of CD205-targeted antigens in the calf model. [Copyright &y& Elsevier]

Abstract: The effector mechanisms used by CD4+ T cells to control mycobacteria differ between humans and rodent models of TB and should be investigated in additional animal models. In these studies, the bovine model was used to characterize the mycobactericidal CD4+ T cell response induced by vaccination with the attenuated Mycobacterium bovis bacillus Calmette-Guérin (BCG). Antigenic stimulation of peripheral blood CD4+ T cells from BCG-vaccinated cattle enhanced expression of perforin and IFNγ in cells expressing a CD45RA−CD45RO+CD62L+ cell surface phenotype, enhanced transcription of granulysin, IFNγ, perforin, IL-4, IL-13, and IL-21, and enhanced anti-mycobacterial activity of CD4+ T cells against BCG-infected macrophages. [Copyright &y& Elsevier]