Identification of a highly conserved and surface-exposed B-cell epitope in snake venom L-amino acid oxidases

L-amino acid oxidase (LAAO) is a major component of snake venoms and contributes to several pathological effects associated with envenomation. However, the identification of immunodominant B-cell epitopes within this toxin remains poorly explored. In this study, native LAAO from Bothrops atrox venom was purified and used to generate polyclonal antibodies in rabbits. Anti-LAAO IgG antibodies were purified and employed in SPOT synthesis-based epitope mapping using a peptide array comprising 122 overlapping pentadecapeptides covering the complete amino acid sequence of B. atrox LAAO (GenBank: ALL27300.1). Five antigenic regions distributed throughout the N-terminal, central, and C-terminal portions of the toxin were identified. Subsequent bioinformatic analyses, including epitope prediction and structural evaluation, identified PEP1 (VGEVNKDPGVLEYPVKPSEVGKS) as the most promising candidate. This peptide was synthesized and evaluated as an immunogen in mice. Immunization with PEP1 elicited antibodies capable of recognizing both the synthetic peptide and native LAAO, as well as cross-reacting with crude B. atrox venom. Sequence alignment demonstrated that this epitope is highly conserved among LAAOs from different snake species. These findings identify a conserved and immunoreactive linear B-cell epitope of LAAO, providing a basis for future studies exploring its use in immunogen design and antivenom development.