SVILUPPO DI METODICHE PER LA DIAGNOSI DELLA BABESIOSI BOVINA E RICERCA DI CANDIDATI VACCINALI IN BABESIA BIGEMINA

Cattle babesiosis is a tick-borne disease transmitted by haemoparasites belonging to the phylum of Apicomplexa, such as Babesia bovis and B.bigemina. The pathology affects cattle mainly in tropical and subtropical areas, but also in Europe, strongly reducing meat and milk production. The study performed during these three years of PhD was addressed to the molecular characterization of Italian B.bigemina strains isolated from infected animals, with attention to the genes codifying for surface antigens, putative candidates for vaccine and diagnostic tools development. One of the molecules potentially involved in the erythrocyte invasion by B.bigemina is the Apical Membrane Antigen-1 (AMA-1), an apical protein having a role in the host red blood cells invasion. In this study the AMA-1 sequences from many Apicomplexa were compared and useful information on this gene from Italian strains of B.bigemina is provided. Preliminary data about the immunogenicity of the purified protein obtained by synthesis in E.coli are reported. We further report the sequences of the rap-1b and gp45 genes from Italian strains of B.bigemina. The rhoptry associated protein-1 (rap-1) is an interesting vaccine candidate against bovine babesiosis. gp45 is one of the surface antigens bound to the membrane by a Glycosylphosphatidylinisotol (GPI-anchor MSA), which have an important role in the bovine erythrocyte invasion by the parasite. Sequence analyses revealed that B.bigemina Gp45 is highly polymorphic, suggesting that it doesn't seem a good vaccine candidate. Its variability could make this gene a molecular marker useful for strain discrimination. The study concerned also a region initially considered homologous to B.bovis SBP-1 gene. The research was addressed to the optimization of diagnostic tools based on Real Time PCR protocols using both SYBR Green and TaqMan strategies. In conclusion, our results provide useful information about the parasite and contribute to the improvement of disease control, in concert with the study of potential vaccine and diagnostic tools.