SLC44A4 and infection: At a high intensity infection, CTL4-knockout mutants yielded a median of 2 oocysts/midgut, as compared to 32 for the control, and the prevalence of infection also significantly (p < 0.0001) decreased 2.2-fold, from 97.3% to 45.0% at 8 d PBM (Fig 2F and S2 Table).