In vitro activation of CMV-specific human CD8+ T cells by CyaA toxoids delivering pp65 epitopes

In this study, we investigated the capacity of two CyaA constructs to deliver epitopes from the CMV phosphoprotein pp65 to activate T cells of CMV-seropositive and CMV-seronegative healthy donors in vitro. Immune response of T cells was monitored using Flow cytometry and Cytometric Beads Array. Expansion of CMV-specific T cells secreting gamma-interferon as well as increase of total IFN-gamma and TNF-alfa; production could be detected after in vitro stimulation with CyaA-CMV constructs, while limited activation of T cells occurred with free peptides. No immune response was evoked by control CyaA without CMV antigenic peptides. These data reveal the potential of CyaA constructs as a tool for fast and reliable detection of CMV-specific immunity and for immunoprophylactic, as well as immunotherapeutic application against CMV-associated diseases in immunocompromised patients.