The influence of ontogeny on Bothrops erythromelas snake venom: Compositional and functional changes and the first report of L-amino acid oxidase in this species.

Snakebites are classified as a neglected tropical disease due to its global impact. The genus Bothrops is the main responsible for envenoming in Brazil, with symptoms that are both local and systemic. Snake venoms are subject to intraspecific variation related to several internal and external factors, including ontogeny. Bothrops erythromelas are small snakes with generalist feeding habits and the ontogenetic variation in its venom has not yet been fully elucidated. Thus, the present work aimed to biologically and biochemically characterize the venom of B. erythromelas snakes from neonates to adults. Compositional analysis of neonates' venom showed a protein profile predominated by high molecular mass bands, which decreased as the animals matured. Contrarily, the regions comprising intermediate and low mass proteins increased in higher ages. In the chromatograms of the venoms, we highlight a shift of peaks in the region predominantly composed of metalloproteases, which may be related to coagulant and collagenolytic activities. Interestingly, L-amino acid oxidase (LAAO) activity was detected in the venom of male adults, so the venom of the one individual that presented the highest activity was submitted to mass spectrometry analysis, confirming its presence in the venom of this species for the first time. Concerning the activities, collagenolytic, LAAO, hemorrhagic, and lethal activities were higher in older animals, while phospholipase A, caseinolytic, cytotoxic, and coagulant activities were higher in neonates and juveniles. The immunorecognition assay showed that the venoms of adults were more reactive than those of younger snakes. Nonetheless, proteolytic and coagulant activities in vitro were partially inhibited, whilst hemorrhagic activity were almost completely neutralized. These results altogether, along with literature, highlight the importance of studying intraspecific variation of snake venoms in order to deepen our understanding of the biology of these animals and as means to improve antivenom treatment.