Specific activation of CMV-primed human T lymphocytes by cytomegalovirus pp65 expressed in fission yeast

Threatening virus infections constantly illustrate the growing need for novel vaccines that specifically induce efficient T cell-mediated immune responses. In this study, we used a human whole blood assay to determine the activation of antigen-specific human T lymphocytes by a viral antigen of human cytomegalovirus (HCMV). The major HCMV tegument protein pp65, recombinantly expressed in fission yeast (Schizosaccharomyces pombe), specifically activated antigen-specific CD4- and CD8-positive memory T cells in blood of HCMV seropositive donors. Moreover, the immune response against recombinant pp65, in particular that of CD8 class I major histocompatibility complex-restricted cytotoxic T cells, was similar to the response against the intact HCMV. Since fission yeast cells per se did not activate a significant number of human T lymphocytes ex vivo, the system described here might represent a novel approach in vaccine development as well as in the identification of vaccine candidates directly from human whole blood. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.