Echinococcus granulosus calreticulin: molecular characterization and hydatid cyst localization.

Hydatidosis, whose etiological agent is the larval stage of the platyhelminth parasite Echinococcus granulosus, is a major zoonotic public health problem and causes great economic losses in many countries, affecting humans and livestock species. Calreticulin (CRT) is a multifunctional and conserved chaperone calcium-binding protein, present in every cell of higher organisms, except erythrocytes. In other parasites species, CRT emerges as a key modulator of several immunological aspects of their relationships with their vertebrate hosts. We report herein the cloning of two DNA segments coding for sequences of E. granulosus CRT (EgCRT). Together with another partial sequence available at the NCBI database, a complete EgCRT cDNA sequence is now proposed. EgCRT mRNA is equally expressed in fertile and infertile hydatid cysts germinal layers, as well as in protoscoleces. In hydatid cysts, EgCRT is a 50 kDa protein, expressed in germinal layer and protoscoleces, mainly in perinuclear and cytoplasmic zones.