Protection against tuberculosis with homologous or heterologous protein/vector vaccine approaches is not dependent on CD8+ T cells

• Published in: The Journal of immunology (1950) 2013-09, Vol.191 (5), p.2514-2525
• Main Authors: Baldwin, Susan L, Ching, Lance K, Pine, Samuel O, Moutaftsi, Magdalini, Lucas, Elyse, Vallur, Aarthy, Orr, Mark T, Bertholet, Sylvie, Reed, Steven G, Coler, Rhea N
• Format: Article
• Language: English
• Subjects: Adenoviridae - genetics; Adenovirus; Adjuvants, Immunologic - administration & dosage; Animals; Antigens, Bacterial - immunology; Blotting, Western; CD8-Positive T-Lymphocytes - immunology; Enzyme-Linked Immunosorbent Assay; Female; Flow Cytometry; Genetic Vectors; Immunization, Secondary - methods; Mice; Mice, Inbred C57BL; Mycobacterium; Mycobacterium tuberculosis; Recombinant Fusion Proteins - immunology; Tuberculosis - immunology; Tuberculosis - prevention & control; Tuberculosis Vaccines - immunology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.1301161

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.