Dual Effects of a Bothrops asper Phospholipase A₂: Anti-Vibrio Properties and Shrimp Hemocyte Cytotoxicity

Emerging antibiotic-resistant Vibrio spp. strains have caused recurrent outbreaks, resulting in substantial losses in shrimp farming and aquaculture production. This ongoing crisis calls for innovative strategies to mitigate its impact, particularly in resource-limited countries that depend heavily on the shrimp industry. In this context, biodiscovery initiatives focused on snake venom toxins with antimicrobial properties represent a promising alternative. Accordingly, we investigated the anti-Vibrio activity of a catalytically inactive phospholipase A₂ (Lys49 PLA₂) purified from the venom of Bothrops asper, a venomous snake commonly found in Ecuador. This novel bioactive biomacromolecule, termed BaETx, was isolated from a venom pool using a one-step purification approach. Mass spectrometry analysis revealed a molecular mass of 13.6 kDa, consistent with its electrophoretic mobility in one-dimensional SDS-PAGE. Structurally, BaETx exhibits high similarity to the amino acid sequences of PLA₂s previously reported from B. asper venoms in other geographical regions. Bioactivity screening demonstrated that BaETx significantly inhibited the in vitro growth of three Gram-negative Vibrio spp. pathogens. Further mechanistic insights obtained through electron and fluorescence microscopy suggest a membrane-damaging actitvity. However, BaETx also significantly reduced shrimp hemocyte viability, indicating non-selective action and limiting its direct application in aquaculture. In addition, computational sequence analysis identified cationic antimicrobial fragments that warrant further investigation. Overall, this study reports the first purification and characterization of an antimicrobial protein from Ecuadorian snake venom, highlighting its potential as a molecular template for the development of shorter and more selective synthetic peptides targeting white shrimp pathogens.