Claire Becker

Abstract :

Babesia divergens is a protozoan parasite of bovine red blood cells. It is transmitted by the hard tick Ixodes ricinus. The life cycle of this parasite inside its vector is not precisely known. The aim was here to identify the transmission stages of B. divergens, on one hand the sporozoite (transmission from the vector to the vertebrate host) and on the other hand the gametocyte (transmission from the vertebrate to the vector). First numerous tick experimental infections were conducted to isolate the sporozoites from the tick transmitting organ, the salivary glands. Even if no parasite could be isolated for B. divergens, the identification of sporozoites from another species B. sp. EU1 inside I. ricinus confirmed that the developed methods were appropriate. Concerning the gametocyte, genes, that are conserved among the Apicomplexa and specific of sexual stages, were selected in P. falciparum genome by bioinformatics. Three orthologs bdccp1, 2 & 3 were identified in B. divergens and their mRNA were proved to be present inside the intraerythrocytic parasite population. The study of one of the corresponding proteins, BdCCp2, using immune sera directed against recombinant peptides, confirm the existence of B. divergens’ sexual stages inside tick gut. Produced tools and methods will allow the acquisition of knowledge on B. divergens’ transmission.