Generation of cytotoxic T-cell lines using overlapping pentadecapeptides derived from conserved regions of the adenovirus hexon protein

Abstract

Many of the 51 serotypes of adenovirus have been associated with clinically relevant infection. Adenovirus can disseminate rapidly in patients with a compromised immune system, such as that which occurs secondary to haematopoietic progenitor-cell transplantation. The higher rate of infection in recipients of T cell-depleted grafts and in those undergoing T cell-targeted treatment during graft versus host disease demonstrates the importance of a T-cell response in preventing disseminated infection. Studies have shown that the memory response to adenovirus is directed primarily to the hexon protein and is dominated by CD4+ T cells, probably due to the ability of the virus to block its presentation on HLA class I antigens. We have developed an approach to expand adenovirus-specific T cells using a pool of overlapping pentadecapeptides derived from selected conserved regions of hexon. We characterized responses to identify the peptides that are recognized, the responding T-cell subsets and their HLA restriction. Of eight lines that were characterized extensively, seven included both CD4+ and CD8+ T cells and each recognized between two and eight unique peptide sequences. By focusing the response on the conserved sequences of hexon, the cell lines are likely to recognize most of the serotypes responsible for clinically relevant disease. The 15 aa peptides used to prime the responses are more likely than whole virus or longer peptides to expand the less frequent CD8+ memory subset. Lines prepared by using our method may be more effective in adoptive immunotherapy protocols designed to prevent or treat disseminated adenovirus infections in high-risk patients.