A marked upregulation of OX40 is observed on Plasmodium specific CD4+ T cells that are generated in both human and rodent malaria blood stage infections and, in rodent studies, α-OX40 treatment was shown to increase parasite-specific memory CD4+ T cells resulting in a reduced blood-stage infection (Zander et al., 2015, 2017; Goncalves-Lopes et al., 2016). The gene discussed is CD4; the disease is infection.