Characterization of CD8⁺ T cell function and immunodominance generated with an H₂O₂-inactivated whole-virus vaccie

CD8⁺ T cells play an important role in protection against both acute and persistent viral infections, and new vaccines that induce CD8⁺ T cell immunity are currently needed. Here, we show that lymphocytic choriomeningitis virus (LCMV)-specific CD8⁺ T cells can be generated in response to a nonreplicating H₂O₂-inactivated whole-virus vaccine (H₂O₂-LCMV). Vaccineinduced CD8⁺ T cell responses exhibited an increased ability to produce multiple cytokines at early time points following immunization compared to infection-induced responses. Vaccination with H₂O₂-LCMV induced the expansion of a narrow subset of the antigen-specific CD8⁺ T cells induced by LCMV strain Arm infection, resulting in a distinct immunodominance hierarchy. Acute LCMV infection stimulated immunodominance patterns that shifted over time or after secondary infection, whereas vaccine- generated immunodominance profiles remained remarkably stable even following subsequent viral infection. Vaccine-induced CD8⁺ T cell populations expanded sharply in response to challenge and were then maintained at high levels, with responses to individual epitopes occupying up to 40% of the CD8⁺ T cell compartment at 35 days after challenge. H₂O₂-LCMV vaccination protected animals against challenge with chronic LCMV clone 13, and protection was mediated by CD8⁺ T cells. These results indicate that vaccination with an H₂O₂-inactivated whole-virus vaccine induces LCMV-specific CD8⁺ T cells with unique functional characteristics and provides a useful model for studying CD8⁺ T cells elicited in the absence of active viral infection.