Characterization of HLA-DP and DQ restricted dengue virus-specific CD4+T cell responses reveals lower magnitude responses associated with a differential pattern of immunodominance as compared to DR restricted responses

Abstract

Abstract Background Assessment of adaptive immunity is an important element to understand immunopathology and to define the correlates of protection against dengue virus (DENV). While previous studies characterized responses restricted by the HLA DRB1 locus, the responses associated with the DP and DQ loci have not been characterized to date. Accordingly, here we mapped HLA DP and DQ restricted DENV-specific CD4 T cell epitopes in PBMCs from individuals previously exposed to DENV from the general population of the Sri Lanka. Methods We studied the DP (*0101, *0201, *0401, *0402) and DQ (*0501, *0602, *0301, *0302, *0201) allelic variants which provide a greater than 80% population coverage worldwide. CD4+ T cells purified by magnetic bead negative selection were cultured for two weeks with autologous APC and pools of HLA –specific predicted binders and tested for reactivity in a standard IFNγ ELISPOT assay. Results Magnitude of responses for both the DP and DQ loci were significantly lower than previously observed for the DRB1 locus. This was correlated with lower membrane expression of HLA- DP and DQ molecules on the PBMCs as compared to HLA DR. While responses against Capsid were dominant for the various DR and DP alleles this protein was hardly recognized by DQ alleles. Responses against NS3 were dominant in the case of DR and DQ but absent in the case of DP, and response to NS1 were prominent in the case of the DP alleles, but negligible in the case of the DR and DQ alleles tested. Conclusion The HLA DP and DQ loci mediate DENV-CD4 specific immune responses of lower magnitude as compared to HLA DRB1. The responses mediated by the DP and DQ loci are also associated with distinct and characteristic patterns of immunodominance.