Analysis of putative amino acids transporters from Echinococcus granulosus.

CAMICIA, F.; CHALAR, C.; GUTIERREZ, A.M.; ROSENZVIT, M.C.

Glasgow, Escocia, Reino Unido

Congreso; The 11th International Congress of Parasitology (ICOPA XI); 2006

The World Federation of Parasitologists and The British Society

The cestode Echinococcus granulosus is the causative agent of cystic hydatid disease, a major zoonosis that affects many areas around the world. A number of cDNAs coding for secreted and membrane bound proteins from E. granulosus were isolated by the signal sequence trap technique. Several of the identified cDNAs, including EgP3G2 and EgP36G2, showed nucleotide and amino acid sequence similarity with neutral amino acid and glutamate transporters belonging to the dicarboxylate/amino acid:Cation (Na+ or H+) symporter (DAACS, TC 2.A.23 ) family. Additional bioinformatics? tools, hydrophilicity plots, sites of glycosilation, confirmed this hypothesis. EgP20C2 cDNA, showed sequence similarity with Krebs-cycle intermediates transporters belonging to the Divalent Anion:Na+ Symporter (DASS, TC 2.A.47)family. Since E. granulosus lacks a digestive tract and all nutrients must enter through the tegument of the worm or the larvae, it is expected that some of these transporters are localized in the tegument of the worm or larvae. In situ hybridization analysis showed that EgP3G2 is expressed in the tegument of protoscoleces (larvae) while EgP36G2 showed homogeneous localization with intense staining of isolated parenchymal cells of protoscoleces and localization in the wall of the brood capsules. Hydrophilic segments of these proteins have been expressed in E.coli and used for immunization of rabbits. Immunolocalisation experiments with the sera obtained are underway. The characterization, including functional studies, of transporter molecules localized to the surface of parasites and the comparison to the corresponding host molecules would allow the identification of selective portals for the entry of drugs and potential targets for new therapeutic drugs and/or immunoprophylaxis.