However, others and we have shown that CD4+ T cells can also function as cytotoxic T cells and are enriched in the CD4-TEMRA compartment and show marked T cell antigen receptor (TCR) clonal expansion similar to the CD8-TEMRA cells in many acute and chronic viral infections including the cytomegalovirus (CMV) [1, 3, 4, 6, 16–22]. The gene discussed is CD4; the disease is viral infectious disease.