By analyzing PBMC samples obtained from HCPS patients with MHC/peptide tetramer staining we showed that there were high frequencies of SNV epitope-specific CD8+ T cells in the acute phase [60] compared to the frequencies of epitope-specific CD8+ T cells in the acute phases of other viral infections, such as human immunodeficiency virus, hepatitis C virus, hepatitis B virus, vaccinia virus and dengue virus, quantitated by MHC/peptide tetramer staining, in which the frequencies were often <1% [73–81]. Here, CD8A is linked to viral infectious disease.