The overexpression of Programmed cell death-1 (PD-1) and Cytotoxic T-lymphocyte-Associated protein 4 (CTLA-4), co-inhibitory receptors [105] is a common feature of T-cell exhaustion found in EBOV [106] and SARS-CoV-2 [107] infections. The gene discussed is CTLA4; the disease is infection.