Genetic disruption of nucleoside transporter 4 reveals its critical roles in malaria parasite sporozoite functions

ABSTRACT

All protozoan parasites are lacking the pathway to synthesize purines de novo and therefore they depend on their host cells to provide purines. A number of highly conserved nucleoside transporter (NT) proteins are encoded in malaria parasite genomes, of which NT1 is characterized in Plasmodium falciparum and P. yoelii as a plasma membrane protein that is responsible for salvage of purines from the host, and NT2 is an endoplasmic membrane NT protein. Whereas NT3 is only present in primate malaria parasites, little is known about NT4, which is conserved in all malaria parasite species. Herein, we targeted NT4 gene for deletion in P. berghei. NT4 knockout parasites developed normally as blood stages, ookinetes and formed oocysts with sporozoites compared with wild-type (WT) P. berghei ANKA parasites. However, nt4(-) sporozoites showed significantly decreased egress from oocysts to hemolymph, significant reduction of colonization of the salivary glands, and complete abolishment of infection of the mammalian host by salivary gland and hemolymph sporozoites. Therefore, we identify NT4 as a NT that is important, not for replication and growth, but for sporozoite infectivity functions.

KEYWORDS:

• Malaria
• P. berghei ANKA
• nucleoside transporter 4
• hemolymph sporozoites
• oocyst sporozoites
• salivary gland sporozoites

Acknowledgments

G.D. thanks the Scientific and Technological Research Council of Turkey (TUBITAK-BIDEB 2211-C PhD Scholarship) for financial support. We are thankful to Elif Kurt for her help in animal care and insectary maintenance.

Author’s contribution

Conceptualization: A.S.I.A.; Methodology: G.D., M.K. and A.S.I.A, U.Y.K; Data analysis: G.D., M.K. and A.S.I.A.; Supervision and Funding acquisition: A.S.I.A and B.A.T; Writing and editing of the manuscript: G.D, M.K., A.S.I.A.

Disclosure statement

No conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/20477724.2022.2112880

Additional information

Funding

This work was supported by the Bezmialem Vakif University Scientific Research Projects (BAP) [grant number: 20201222] and Scientific and Technological Research Council of Turkey (TÜBİTAK) [grant number: 119Z409].