Comparison of the outcome of Plasmodium infection in RAG2−/− mice, which have normal NK cell numbers but lack T and B cells, and RAG2−/− γc−/− mice, which lack T, B and NK cells, showed that NK cells act on the pre-erythrocytic phase of parasite development in vivo as RAG2−/− γc−/− mice are more sensitive to sporozoite infection than RAG2−/− mice, whereas survival rates are similar for the two strains following infection with parasitized RBCs [4]. The gene discussed is GC; the disease is infection.