Viruses employ various means to evade immune detection. One common evasion strategy is the removal of CD8+cytotoxic T-lymphocyte epitopes. We here use a combination of multiple bioinformatic tools and large amount of genomic data to compute the epitope repertoire presented by over 1300 viruses in many HLA alleles. We define the Size of Immune Repertoire score, which represents the ratio between the epitope density within a protein and the expected density. This score is used to study viral immune evasion.