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Abstract

Malaria, caused by Plasmodium parasites, remains one of the most devastating infectious diseases globally, with transmission relying on the parasite’s complex life cycle between mosquito vectors and mammalian hosts. The sporozoite, the parasite’s transmissive stage, is a highly motile, crescent-shaped cell whose journey from the mosquito midgut to the salivary glands is essential for host infection. Sporozoite motility, egress, and invasion are mediated by surface proteins, among which Thrombospondin-related protein 1 (TRP1) plays a critical role.

In this study, I dissected the functional contributions of distinct TRP1 domains in Plasmodium berghei using genetic and molecular approaches. C-terminal deletion and domain-swap mutants revealed that the TRP1 C-terminus is not required for oocyst egress, contrary to previous reports, but is essential for productive sporozoite motility and salivary gland invasion. Functional specificity was further demonstrated as the P. berghei TRAP C-terminal domain could not substitute for TRP1, whereas the shorter P. falciparum TRP1 C-terminus fully restored function. Mutational analyses of the N-terminal Thrombospondin repeat (TSR) domain identified conserved tryptophan residues as critical for sporozoite motility and salivary gland invasion, with TRAP TSR unable to compensate for TRP1 TSR function.

Dual-tagging and fluorescent labeling of TRP1 provided novel insights into its localization and domain dynamics within sporozoites. Furthermore, proximity-dependent biotinylation using TRP1-APEX identified 307 potential interacting proteins, including nine uncharacterized candidates highly expressed during mosquito stages, suggesting a broader molecular network supporting sporozoite motility and host transmission.

Collectively, this work establishes TRP1 as an indispensable regulator of sporozoite motility and salivary gland invasion, with highly specific domain functions, and identifies candidate interaction partners for future mechanistic studies. These findings advance our understanding of the molecular determinants underlying Plasmodium transmission and highlight TRP1 as a potential target for interventions aimed at blocking malaria transmission.