Germline bias dictates cross-serotype reactivity in a common dengue-virus-specific CD8(+) T cell response

Abstract

Adaptive immune responses protect against infection with dengue virus (DENV), yet cross-reactivity with distinct serotypes can precipitate life-threatening clinical disease. We found that clonotypes expressing the T cell antigen receptor (TCR) beta-chain variable region 11 (TRBV11-2) were 'preferentially' activated and mobilized within immunodominant human-leukocyteantigen (HLA) A* 11: 01-restricted CD8(+) T cell populations specific for variants of the nonstructural protein epitope NS3(133) that characterize the serotypes DENV1, DENV3 and DENV4. In contrast, the NS3(133)-DENV2-specific repertoire was largely devoid of such TCRs. Structural analysis of a representative TRBV11-2(+) TCR demonstrated that cross-serotype reactivity was governed by unique interplay between the variable antigenic determinant and germline-encoded residues in the second beta-chain complementarity-determining region (CDR2 beta). Extensive mutagenesis studies of three distinct TRBV11-2+ TCRs further confirmed that antigen recognition was dependent on key contacts between the serotype-defined peptide and discrete residues in the CDR2 beta loop. Collectively, these data reveal an innate-like mode of epitope recognition with potential implications for the outcome of sequential exposure to heterologous DENVs.