IL-21 is expressed in several murine malaria models, including P. berghei (Ryg-Cornejo et al., 2016; Inoue et al., 2018), Plasmodium chabaudi (Perez-Mazliah et al., 2015; Sebina et al., 2017) and Plasmodium yoelii (Wikenheiser et al., 2018). The gene discussed is IL21; the disease is malaria.