Plasmodium falciparum PF10_0164 (ETRAMP10.3) is an essential parasitophorous vacuole and exported protein in blood stages.

Upregulated in infectious sporozoites gene 4 (UIS4) encodes a parasitophorous vacuole membrane protein expressed in the sporozoite and liver stages of rodent malaria parasites. Parasites that lack UIS4 arrest in early liver-stage development, and vaccination of mice with uis4(-) sporozoites confers sterile protection against challenge with infectious sporozoites. Currently, it remains unclear whether an ortholog of UIS4 is carried in the human malaria parasite Plasmodium falciparum, although the gene PF10_0164 has been identified as a candidate ortholog for UIS4 on the basis of synteny and structural similarity of the encoded protein. We show that PF10_0164 is expressed in sporozoites and blood stages of P. falciparum, where it localizes to the parasitophorous vacuole, and is also exported to the host erythrocyte. PF10_0164 is refractory to disruption in asexual blood stages. Functional complementation was tested in Plasmodium yoelii by replacing the endogenous copy of UIS4 with PF10_0164. PF10_0164 localized to the parasitophorous vacuole membrane of liver stages, but transgenic parasites did not complete liver-stage development in mice. We conclude that PF10_0164 is a parasitophorous vacuole protein that is essential in asexual blood stages and that does not complement P. yoelii UIS4, and it is thus likely not a functional ortholog of UIS4.