Repertoire of P-glycoprotein drug transporters in the zoonotic nematode Toxocara canis

• Published in: Scientific reports 2023-03, Vol.13 (1), p.4971-4971, Article 4971
• Main Authors: Jesudoss Chelladurai, Jeba R. J., Martin, Katy A., Vardaxis, Pam, Reinemeyer, Craig, Vijayapalani, Paramasivan, Robertson, Alan P., Brewer, Matthew T.
• Format: Article
• Language: English
• Subjects: 631/154/436; 631/154/555; 631/326/417/1716; 631/326/417/2552; Animals; ATP Binding Cassette Transporter, Subfamily B - genetics; Dogs; Drug tolerance; Eggs; Gene expression; Genes; Genomes; Glycoproteins; Humanities and Social Sciences; Ivermectin; Ivermectin - pharmacology; Laboratory animals; Lactones; Lactones - metabolism; Larva - metabolism; Larvae; Mammals - metabolism; Motility; multidisciplinary; Nematodes; P-Glycoprotein; Paralysis; Parasites; Permeability; Phylogenetics; Science; Science (multidisciplinary); Toxocara canis; Toxocara canis - metabolism; Verapamil; Veterinary colleges; Veterinary medicine; Worms; Zoonoses
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-31556-1

Toxocara canis has a complex lifecycle including larval stages in the somatic tissue of dogs that tolerate macrocyclic lactones. In this study, we investigated T. canis permeability glycoproteins (P-gps, ABCB1) with a putative role in drug tolerance. Motility experiments demonstrated that while ivermectin failed to abrogate larval movement, the combination of ivermectin and the P-gp inhibitor verapamil induced larval paralysis. Whole organism assays revealed functional P-gp activity in larvae which were capable of effluxing the P-gp substrate Hoechst 33342 (H33342). Further investigation of H33342 efflux demonstrated a unique rank order of potency for known mammalian P-gp inhibitors, suggesting that one or more of the T. canis transporters has nematode-specific pharmacological properties. Analysis of the T. canis draft genome resulted in the identification of 13 annotated P-gp genes, enabling revision of predicted gene names and identification of putative paralogs. Quantitative PCR was used to measure P-gp mRNA expression in adult worms, hatched larvae, and somatic larvae. At least 10 of the predicted genes were expressed in adults and hatched larvae, and at least 8 were expressed in somatic larvae. However, treatment of larvae with macrocyclic lactones failed to significantly increase P-gp expression as measured by qPCR. Further studies are needed to understand the role of individual P-gps with possible contributions to macrocyclic lactone tolerance in T. canis.