Blockade of CTLA-4 and other inhibitory receptors, e.g., lymphocyte-activation gene-3 (LAG-3), programmed death-1 (PD-1), and T-cell immunoglobulin mucin-3 (TIM-3), improved T-cell responses to malaria parasites (Butler et al., 2011; Hafalla et al., 2012; Redmond et al., 2014; Costa et al., 2015; Goncalves-Lopes et al., 2016). The gene discussed is HAVCR2; the disease is malaria.