A myotoxic Lys49 phospholipase A 2 -homologue is the major component of the venom of Bothrops cotiara from Misiones, Argentina.

Bothrops cotiara is a pitviper found in Southeastern Brazil and, scarcely, in the Misiones province of Argentina. In contrast to considerable information available on the venom of the Brazilian snake population, that of Misiones has received little attention. While exploring the chromatographic venom profile of Argentinean B. cotiara, a major protein peak was found which, according to a previous study, is not present in the venom of Brazilian origin. The corresponding protein was isolated by RP-HPLC, and characterized by electrophoresis, mass spectrometry, phospholipase A2 (PLA2 ) assay, and myotoxic activities. Representing nearly 15% of B. cotiara venom from Misiones, this protein was identified as a Lys49 PLA2 homologue. In accordance with the characteristics of this toxin family, the protein induced myotoxicity in mice and was devoid of PLA2 activity. Since previous work reported that no PLA2 or PLA2 -homologues occur in B. cotiara venom of Brazilian origin, the presence of an abundant Lys49 PLA2 homologue in the venom from Misiones highlights a striking phenotypic variation in toxin expression within two populations of a single snake species inhabiting different geographic areas. The considerable proportion of B. cotiara Lys49 PLA2 homologue myotoxin in the venom alerts that skeletal muscle necrosis might be a potentially relevant consequence of eventual envenomings by this species in Misiones.