America, which is considered an ecological danger to the coral reefs because of its invasive behavior. Toxicity in humans is associated with strong pain and local symptomatology. In this study, we evaluated the 24 h-in vivo effects of its venom and fractions on the skin and gastrocnemius muscle of mice. Intraperitoneal injection of lionfish dorsal spines venom (which in this study was not separated from epidermal mucus), is not able to induce lethality up to 250 mg/mouse, but histological analysis shows that 50 mg of venom per mouse, induces myonecrosis and hemorrhage in the gastroc- nemius and damage on the skin, by intradermal injection. Venom was separated by size exclusion-HPLC and five main fractions were obtained, which were injected in mice, and tissue samples were processed for histological analysis. Fraction 1 (containing the highest molecular weight components), which displays proteolytic activity, was able to induce strong myonecrosis but no alterations on the skin were observed, whereas fraction 2, which contains the hemolysin present in all Scorpaenidae fish family members, did not induce damage on muscle or skin. Fraction 3, containing the strongest hyaluronidase activity, was very toxic for the skin tissue, inducing a strong lesion, hemorrhage and increased vascular permeability. It also caused red blood cell aggregation towards the vessel walls. Fraction 4, containing a ~32 kDa very abundant protein with similarity to the secretory cysteine-rich proteins (a Golgi-associated plant pathogen- esis-related protein), induced a lesion and hemorrhage on the skin, but no necrosis in muscle. The same effect was observed with fraction 5, which contains a 14.2 kDa protein, similar to gastrotropin and fatty acid binding proteins. These two components have been found recently in the venom of stonefish (Synanceia horrida), but their effects have not been characterized yet. B. NEUWIEDI COMPLEX: WHAT THE VENOM OF THESE SNAKE SPECIES HAVE IN COMMON? COMPOSITIONAL AND FUNCTIONAL INVESTIGATION OF VENOMS FROM BOTHROPS NEUWIEDI COMPLEX Nath alia da Costa Galizio, Weslei da Silva Aguiar, Caroline Serino- Silva, Caroline Fabri Bittencourt Rodrigues, Daniel Rodrigues Stuginski, Marisa Maria Teixeira da Rocha, Roberto Baptista de Oliveira, S avio Stefanini Sant’Anna, Kathleen Fernandes Grego, Anita Mitico Tanaka-Azevedo, Karen de Morais-Zani. Laborat orio de Herpetologia, Instituto Butantan, S~ ao Paulo, BR, Brazil; Interunidades em Biotecnologia, Instituto de Ci^encias Biomedicas, Instituto de Pesquisas Tecnol ogicas, Instituto Butantan, Universidade de S~ ao Paulo, S~ ao Paulo, BR, Brazil; Núcleo Regional de Ofiologia de Porto Alegre, Fundaç~ ao Zoobot^ anica, Porto Alegre, BR, Brazil The snakes that composed the "B. neuwiedi complex" underwent a taxo- nomic revision and as a result of this analysis, it was proposed that this complex is in fact composed by 7 species: B. neuwiedi (Bn), B. diporus (Bd), B. lutzi (Blu), B. mattogrossensis (Bmt), B. pauloensis (Bpa), B. pubescens (Bpu) and B. marmoratus (Bmm). Since the characterization of the venoms of these species after the taxonomic revision are scarce, the aim of this study is to characterize and compare the protein profile and the enzymatic ac- tivities of venoms from this group. For comparative purposes, we have included the species B. erythromelas (Be) in our analyses. Protein profile obtained by 1-DE stressed the intraspecies venom variation, showing differences concerning the intensity and the presence of particular protein bands. Concerning proteolytic activity, Bpa, Bd and Bpu venoms displayed the lowest activity upon azocasein and collagen, which is corroborated by the low intensity of bands between 50-100 kDa in 1-DE, that comprehend the SVMP-III area. In contrast, Be showed intense bands in this area and more proteolytic activity. Amongst the species analyzed, Be venoms dis- played the lowest thrombin-like activity upon the chromogenic substrate S-2238, followed by the venom of Bmm, while Bn, Bd, Bmt, Bpa and Bpu venoms present similar activity. In vivo assays demonstrate that Bpa, Bd and Bpu are more lethal than the other species. However, Be seems to be the most haemorrhagic of them. Regarding immunerecognition assays, all protein bands resolved by 1-DE of the species analyzed were recognized by bothropic antivenom produced by Instituto Butantan (Western blotting). In addition, venom samples showed comparable immunoreactivity with the same antivenom (ELISA). These results revealed some particular fea- tures of the venoms of the seven species under analysis. The next steps include proteomic analysis by mass spectrometry and comparison of their pathophysiological activities. STRUCTURAL AND FUNCTIONAL COMPARISONS OF THE GPLI FROM VENOMOUS AND NON-VENOMOUS BRAZILIAN SNAKES Caroline Serino-Silva, Caroline Fabri Bittencourt Rodrigues, Kathleen Fernandes Grego, Marcelo Pires Nogueira de Carvalho, Marcos Hikari Toyama, Victor Kavazoi Kavazoi, V. K, Karen Morais-Zani, Anita Tanaka- Azevedo. Instituto Butantan, Brazil; Universidade Federal de Minas Gerais, Brazil; Universidade Estadual Paulista, Brazil During the snake envenomation, phospholipases A2 (PLA2) are respon- sible to local symptoms that cannot be totally neutralized by serum ther- apy. The main natural alternative studied are Phospholipase A2 inhibitors (PLI) from snake blood. Curiously, PLIs are present in venomous snakes, venomous snake and mammals, and their biological role as well as their mechanism of action are not well clarified. So, the aim of the study is to compare the similarities between the BoagPLI from Boa constrictor (non- venomous snake) plasma and gBjPLI from Bothrops jararaca (venomous snake) plasma. Therefore, BoagPLI and gBjPLI were isolated using two chromatographic steps: an ion exchange column (DEAE), followed by an affinity column (crotoxin coupled to a CNBr-activated Sepharose resin). The purity and biochemical characterization were compared and analyzed by Bradford, SDS-PAGE and circular dichroism. The ability to inhibit PLA2 was determined by enzymatic activity. The purification process showed 0.63% and 1% of recovery of BoagPLI and gBjPLI, respectively. The differ- ences in this parameter might be caused by the constant contact of gBjPLI with the venom of the B. jararaca, a venomous snake. The SDS-PAGE showed similar patterns, showing a band of 25 kDa in reducing conditions and 20 kDa in non-reducing conditions. In addition, the BoagPLI showed a band with higher molecular mass, suggesting oligomerization. The sec- ondary structures were similar between the inhibitors. In addition, the inhibitory potential was also similar, about 48% of inhibition of the PLA2 activity. In conclusion, despite the different percentage of recovery, the structural and functional features of these inhibitors were similar. In this context, the study could provide new perspectives for PLA2 inhibitors from snake plasma by characterizing and comparing the PLIs from venomous and non-venomous snakes, which can contribute to the neutralization of the PLA2 effects. UNRAVELLING THE PATHOPHYSIOLOGY OF VASCULAR LEAKAGE INDUCED BY DABOIA RUSSELLI SNAKE VENOM Alexandra Rucavado, Teresa Escalante, Erika Camacho, Jose Maria Guti errez, Jay W. Fox. Instituto Clodomiro Picado, Universidad de Costa Rica, Costa Rica; Institute Clodomiro Picado, Universidad de Costa Rica, Costa Rica; University of Virginia, USA We developed an experimental model to study the systemic capillary leak syndrome (CLS) induced by the venom of D. russelli from Pakistan, based on the determination of blood hematocrit and plasma albumin in mice. The venoms of D. russelli from Pakistan and of B. asper induced two different patterns of vascular toxicity in our model. When injected intra- dermally, B. asper venom caused a local hemorrhage, whereas D. russelli did not elicit hemorrhage but instead induced an increment in vascular permeability. This reveals two distinct paradigms of vascular toxicity, one based on disruption of microvasculature leading to hemorrhage (B. asper) and the other centered in an increment in vascular permeability leading to hemoconcentration (D. russelli). The question is whether the hemo- concentration effect induced by D.russelli (DR) venom is related to acute kidney dysfunction observed in envenoming. In this work we carried out a set of experiments using different inhibitors and specific antibodies to try to address this question. Varespladib, a small compound that has been tested to inhibit the PLA2 catalytic activity in a wide variety of snake venoms (Lewin et al., 2016), did not inhibit the hemoconcentration effect. Likewise, Varespladib was not able to improve renal function or normalize Abstracts / Toxicon 177 (2020) S23eS63 S47