Identification of T-cell epitopes by a novel mRNA PCR-based epitope chase technique

The identification of specific viral and tumor antigen T-cell epitopes remains a challenge. Indeed, epitope mapping methods are generally costly and time-consuming. Thus, few techniques allow for efficient CD4+ T-lymphocyte epitope identification. Here, we introduce a novel polymerase chain reaction-based mRNA epitope identification method, called mPEC, to rapidly and precisely identify relevant T-cell epitopes recognized by CD8+ or CD4+ T lymphocytes. This method is based on the use of mRNA fragments synthesized from polymerase chain reaction-amplified cDNA with a choice of 3'end deletions. mRNA fragments are electroporated into autologous antigen-presenting cells to deduce an epitope's localization in a given protein antigen. Considering mRNA's sensitivity to degradation, we also inserted a defined epitope at the mRNA's 3'end to control for electroporated mRNA's integrity and its capacity to be translated. Using this method, we rapidly and successfully identified the specific epitope of 2 CD8+ and 1 CD4+ T-lymphocyte clones derived from influenza model antigens. Hence, mPEC could be used to identify new, in vivo-relevant T-cell epitopes for cancer immunotherapy and vaccination in general.