W159 - Identification of B Cell Epitopes of BIP and α-1 Giardin Proteins from Giardia Lamblia

Abstract Text: Giardiasis is a global health problem caused by the parasite Giardia lamblia. Current treatments often lead to side effects and fail to prevent reinfections. Actually, there is no vaccine for human infections, highlighting the need to elucidate the immunological mechanisms triggered during infection to develop new therapeutic strategies. Our research group is investigating immunogenic proteins from G. lamblia as potential vaccine candidates, including BIP and α-1 giardin. The B- and T-cell epitopes of these immunogenic antigens remain unknown. Therefore, the aim of this study was to identify regions within the BIP and α-1 giardin proteins that contain B cell epitopes. To achieve this, specific polyclonal antibodies against these proteins were generated by intraperitoneal immunization in Balb/c mice. Experimental data obtained by Western Blotting assays, combined with in silico analysis, revealed that the amino acid region 237(ILE)-511(ILE) of the BIP protein contains immunogenic B cell epitopes. Furthermore, specific B cell hybridomas targeting BIP were generated, allowing the purification of the monoclonal antibody 6H2.H7, which is currently being characterized. In the case of the giardin α-1 protein, immunogenic fragments were identified by western blotting and electrospray ionization mass spectrometry, determining that the amino acid sequence 15(ISO)-73(ASP) was immunogenic. Identifying these immunogenic regions in G. lamblia proteins is crucial for understanding the parasite's immunological interactions with its host. Furthermore, this information will guide the design and development of a multipeptide vaccine able of eliciting an effective immune response against the parasite.