An environment that impairs the peptide transporter TAP, which can be inhibited by a viral infection or in tumour tissue, can determine a reduction in availability of HLA-I leader peptides and can lead to an alternative repertoire of peptides being presented in the context of HLA-E; this can subsequently impact the outcome of the viral infection or the elimination of damaged or neoplastic cells [24–26]. This evidence concerns the gene HLA-E and viral infectious disease.