Interestingly, while oocyst-derived sporozoites that lack ECP1 or express mutated CS are not infective to mice, the mechanically liberated oocyst-derived sporozoites of mutants lacking PFD0425w are able to establish an infection in mice by i.v. inoculation, and this implies that PFD0425w - in contrast to ECP1 - has no additional function during infection of the mammalian host. This evidence concerns the gene CS and infection.