Lipid transport proteins in Toxocara canis: Host lipid acquisition and immune modulation.

Abstract

Toxocara canis is unable to synthesize sufficient lipids de novo to meet its biological requirements and therefore depends on host-derived lipids for survival. The parasite expresses a diverse set of lipid transport proteins spanning all major classes, such as pseudocoelomic fluid lipoproteins (vitellogenins), nematode polyprotein antigens/allergens, intracellular carriers (fatty-acid binding proteins, phosphatidylinositol-transfer proteins), secreted lipid-binding proteins (fatty acid-and retinol-binding proteins, venom allergen-like proteins), membrane-associated transporters (Niemann-Pick C, ABC transporters, microsomal triglyceride transfer protein, bridge-like lipid-transfer proteins) and lipid-anchored carriers (phosphatidylethanolamine-binding proteins). These proteins mediate uptake and distribution of dietary and host lipids to drive parasite growth and reproduction, while simultaneously modulating host immune responses. Many of these transporters are released in the parasite's excretory/secretory products and are found in extracellular vesicles, where they mediate host-parasite interactions and immunomodulation. These specialized lipid-acquisition strategies support parasite survival, drive immune evasion and pathogenesis, and highlight these proteins as candidates for novel diagnostics or therapeutic targets.