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The value of predictive algorithms for identifying CD8+ T (TCD8+)-cell epitopes has not been adequately tested experimentally. Here we demonstrate that conventional bioinformatic methods predict the vast majority of TCD8+-cell epitopes derived from vaccinia virus WR strain (VACV-WR) in the H-2b mouse model. This approach reveals the breadth of T-cell responses to vaccinia, a widely studied murine viral infection model, and may provide a tool for developing comprehensive antigenic maps of any complex pathogen. [ABSTRACT FROM AUTHOR]

Considerable effort has been directed to develop Mycobacterium tuberculosis vaccines to boost bacille Calmette-Guérin or for those who cannot be immunized with bacille Calmette-Guérin. We hypothesized that CD4+ and CD8+ T cell responses with a heterologous prime/boost vaccine approach could induce long-lived vaccine efficacy against M. tuberculosis in C57BL/6 mice. We produced an adenovirus vector expressing ID93 (Ad5-ID93) for induction of CD8 T cells to use with our candidate tuberculosis vaccine, ID93/glucopyranosyl lipid adjuvant (GLA)-stable emulsion (SE), which induces potent Th1 CD4 T cells. Ad5-ID93 generates ID93-specific CD8+ T cell responses and induces protection against M. tuberculosis. When Ad5-ID93 is administered in a prime-boost strategy with ID93/GLA-SE, both CD4+ and CD8+ T cells are generated and provide protection against M. tuberculosis. In a MHC class I-deficient mouse model, all groups including the Ad5-ID93 group elicited an Ag-specific CD4+ T cell response and significantly fewer Ag-specific CD8+ T cells, but were still protected against M. tuberculosis, suggesting that CD4+ Th1 T cells could compensate for the loss of CD8+ T cells. Lastly, the order of the heterologous immunizations was critical. Long-lived vaccine protection was observed only when Ad5-ID93 was given as the boost following an ID93/GLA-SE prime. The homologous ID93/GLA-SE prime/boost regimen also induced long-lived protection. One of the correlates of protection between these two approaches was an increase in the total number of ID93-specific IFN-γ-producing CD4+ T cells 6 mo following the last immunization. Our findings provide insight into the development of vaccines not only for tuberculosis, but other diseases requiring T cell immunity. [ABSTRACT FROM AUTHOR]

Diagnosis of tuberculosis often relies on the ex vivo IFN-γ release assays QuantiFERON-TB Gold In-Tube and T-SPOT.TB. However, understanding of the immunological mechanisms underlying their diagnostic use is still incomplete. Accordingly, we investigated T cell responses for the TB Ags included in the these assays and other commonly studied Ags: early secreted antigenic target 6 kDa, culture filtrate protein 10 kDa, Rv2031c, Rv2654c, and Rvl038c. PBMC from latently infected individuals were tested in ex vivo ELISPOT assays with overlapping peptides spanning the entirety of these Ags. We found striking variations in prevalence and magnitude of ex vivo reactivity, with culture filtrate protein 10 kDa being most dominant, followed by early secreted antigenic target 6 kDa and Rv2654c being virtually inactive. Rv2031c and Rvl038c were associated with intermediate patterns of reactivity. Further studies showed that low reactivity was not due to lack of HLA binding peptides, and high reactivity was associated with recognition of a few discrete dominant antigenic regions. Different donors recognized the same core sequence in a given epitope. In some cases, the identified epitopes were restricted by a single specific common HLA molecule (selective restriction), whereas in other cases, promiscuous restriction of the same epitope by multiple HLA molecules was apparent. Definition of the specific restricting HLA allowed to produce tetrameric reagents and showed that epitope-specific T cells recognizing either selectively or promiscuously restricted epitopes were predominantly T effector memory. In conclusion, these results highlight the feasibility of more clearly defined TB diagnostic reagent. [ABSTRACT FROM AUTHOR]