Indeed, the reciprocal chimera CD81ccg9 supported P. yoelii sporozoite infection after transient transfection in HepG2-A16 cells (Fig. 1B–C), showing that CD81 A and B helices in a CD9 backbone are sufficient to confer HepG2-A16 cells the ability to support infection by P. yoelii sporozoites. The gene discussed is CD9; the disease is infection.