Phenotypic and Functional Differences between Human Herpesvirus 6- and Human Cytomegalovirus-Specific T Cells

Abstract

T cells are central to an effective defense against persistent viral infections that can be related to human cytomegalovirus (HCMV) or human herpesvirus 6 (HHV-6). However, knowledge of HHV-6-specific T-cell responses is limited. In order to deepen our knowledge of T-cell responses to HHV-6, we characterized HHV-6A- and HHV-6B-specific CD4 + and CD8 + T-cell responses directly ex vivo from healthy coinfected blood donors. Despite the strong similarity of HHV-6 and HCMV from a virologic point of view, we observed immunological differences, particularly in relation to the frequency and phenotype of effector/memory and regulatory virus-specific T cells. This suggests that different immune factors are solicited in the control of HHV-6 infection than in that of HCMV infection. Our findings may encourage immunomonitoring of patients with viral replication episodes to follow the emergence of effector versus regulatory T cells.