New multienzymatic complex formed between human cathepsin D and snake venom phospholipase A2

Background Cathepsin D (CatD) is a lysosomal proteolytic enzyme expressed in almost all tissues and organs. This protease is a multifunctional enzyme responsible for essential biological processes such as cell cycle regulation, differentiation, migration, tissue remodeling, neuronal growth, ovulation, and apoptosis. The overexpression and hypersecretion of CatD have been correlated with cancer aggressiveness and tumor progression, stimulating cancer cell proliferation, fibroblast growth, and angiogenesis. In addition, some studies report its participation in neurodegenerative diseases and inflammatory processes. In this regard, the search for new inhibitors from natural products could be an alternative against the harmful effects of this enzyme. Methods An investigation was carried out to analyze CatD interaction with snake venom toxins in an attempt to find inhibitory molecules. Interestingly, human CatD shows the ability to bind strongly to snake venom phospholipases A2 (svPLA2), forming a stable muti-enzymatic complex that maintains the catalytic activity of both CatD and PLA2. In addition, this complex remains active even under exposure to the specific inhibitor pepstatin A. Furthermore, the complex formation between CatD and svPLA2 was evidenced by surface plasmon resonance (SPR), two-dimensional electrophoresis, enzymatic assays, and extensive molecular docking and dynamics techniques. Conclusion The present study suggests the versatility of human CatD and svPLA2, showing that these enzymes can form a fully functional new enzymatic complex.

Toxic systemic reaction after bee stings in a bitch

Background: Bee sting poisonings are common in dogs, and toxic systemic presentation may represent a life-threatening condition. Apis mellifera venom is a complex mixture of melitin, apamine, phospholipase, hyaluronidase and degranulating peptides, that causes local injury at the site of inoculation and multiple organ complications, including hemolysis, kidney injury, muscular damage, cardiovascular and respiratory complications. The present work reports a complete and detailed description of a dog's systemic toxic reaction to bee stings, including history, clinical signs, laboratory findings, emergency care and development, as well as possible association with later immunomediated arthritis. Case: A 6-year-old female German Shepperd suffered multiple bee stings. First care was conducted by a veterinary at the site, where he only received promethazine, meloxicam and dexamethasone. After 24 h and significant progression of symptoms, the animal was forwarded to a specialized veterinary hospital. The patient was evaluated throughout 9 days, and presented intense edema, respiratory distress, tongue necrosis and grade II of acute kidney injury. Extensive laboratory exams were conducted throughout the hospitalization. Main laboratory findings included polycythemia, leukocytosis by neutrophilia and monocytosis, thrombocytopenia and azotemia. Urinalysis evidenced turbid aspect, dark yellow color and intense proteinuria, reinforcing kidney damage. Abdominal ultrasound examination identified blood clots in the bladder, and liver with reduced echogenicity and echotexture, suggesting acute inflammation. Therapy aimed to stabilize the patient, control kidney damage and avoid anaphylaxis. Treatment included intensive care support, promethazine, hydrocortisone, dexamethasone, dipyrone, methadone, metronidazole, ampicillin, clindamycin and tramadol. Following successful treatment, the animal presented immunomediated polyarthritis, possibly associated to both the poisoning and later diagnosed hemoparasitosis (both Erlichia and Babesia). Discussion: Massive bee attacks can cause severe complications, however, data regarding emergency care records are scarce. Based on clinical signs and laboratory findings, the patient presented toxic systemic reaction, including grade II of acute kidney injury and significant cardiorespiratory distress. Another important complication was tongue necrosis, that demanded attention and special supportive care, including feeding tube and specific feed. Treatment also focused in reducing edema and control possible anaphylaxis, providing analgesia and antibiotic therapy. Laboratory findings have been previously described, with evidence of immune-mediated reaction. Follow-up consultations revealed normal parameters, and an unusual presentation of claudication. Investigation concluded that polyarthritis could be responsible for such finding and may be a result of the deposition of immunomediated complexes in the joints, due in this case to the bee poisoning and later positive diagnosis for both Erlichia and Babesia. Systemic reactions to bee stings are complex, and full clinical and laboratory profile aid in both the prognosis and treatment options. Special attention must be given to tongue damage and supportive care is essential for maintaining feeding conditions. Arthritis should be considered as possible complication, reinforcing the importance of follow-up consultations.

Compositional and toxicological investigation of pooled venom from farm-raised Naja atra

Background: Naja atra is a venomous snake species medically relevant in China. In the current study, we evaluated the composition and toxicological profile of venom collected from farm-raised N. atra. Methods: Venom was collected from third-generation captive bred N. atra on a snake farm in Hunan Province, China. The venom was analyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis and nano-liquid chromatography with electrospray ionization tandem mass spectrometry. In addition, hemolytic activity, median lethal dose, serum biochemical and histopathological parameters were accessed. Results: N. atra venom proteome was dominated by phospholipase A2 (46.5%) and three-finger toxins (41.4 %), and a set of common low relative abundance proteins, including cysteine-rich secretory proteins (4.7%), NGF-beta (2.4%), snake venom metalloproteinase (1.5%), glutathione peroxidase (0.6%), vespryn (0.3%), and 5ʹ-nucleotidases (0.2%) were also found. Furthermore, the venom exhibited direct hemolytic activity, neurotoxicity, myotoxicity, and high lethal potency in mice, with a subcutaneous median lethal dose of 1.02 mg/kg. Histopathological analysis and serum biochemical tests revealed that venom caused acute hepatic, pulmonary and renal injury in mice. Conclusion: This study revealed the composition and toxicity of venom collected from farm-raised N. atra, thereby providing a reference for the analysis of venom samples collected from captive-born venomous snakes in the future.(AU)

Antimicrobial effect of bothropstoxin-i in broilers / Atividade antimicrobiana da bothropstoxin-i em frangos de corte

Bacterial resistance is a sanitary issue explained by indiscriminate use of nonprescription drugs, and antimicrobial use in food production for growth promotion. Bothropstoxin-I (BthTx-I) is a phospholipase A2 (PLA2) from Bothrops jararacussu venom, which has a known antimicrobial effect. The goal of this study was the unprecedented evaluation of in vivo antimicrobial activity of BthTx-I in broilers. Microbiological, biochemical, and histological parameters were determined using 84 21-day old broilers that were kept in cages with four birds each at a density of 625 cm2/broiler. The experiment was randomized by three treatments with seven repetitions of four broilers each that lasted seven days. The treatments were: 1) bacitracin zinc diet; 2) PLA2-BthTx-I; 3) without additives. The data obtained from the studied variables was subjected to analysis of variance and an F-test at the 5% significance level. Averages of each variable in each treatment were compared by Tukey’s test. Broiler bacterial cloacal counts showed that BthTx-I decreased the microbial population without reducing body weight, intestinal morphology, or liver or kidney histopathological damage. The toxin showed in vivo activity, being an alternative for better performance in the production of broiler chickens, because it acted by decreasing the microbial load of potentially pathogenic bacteria in the intestinal(AU)

A resistência bacteriana é uma questão sanitária, explicada pelo uso indiscriminado de medicamentos sem receita médica e pelo uso de antimicrobianos na produção de alimentos para promover o crescimento. Bothropstoxin-I (BthTx-I) é uma fosfolipase A2 (PLA2) obtida do veneno da Bothrops jararacussu. A PLA2 do veneno de cobra tem efeito antimicrobiano conhecido. Objetivou-se com este estudo avaliar sem precedentes a atividade antimicrobiana in vivo de BthTx-I em frangos de corte. Os parâmetros microbiológicos, bioquímicos e histológicos foram realizados em 84 frangos de corte com 21 dias de idade mantidos em gaiolas com quatro animais cada e densidade de 625 cm2/frango. O experimento foi dividido em três tratamentos com sete repetições de quatro frangos cada um, com duração de sete dias. Os tratamentos foram: 1) dieta com bacitracina de zinco; 2) PLA2-BthTx-I; 3) sem aditivos. Os dados obtidos das variáveis estudadas foram submetidos à análise de variância e teste F ao nível de significância de 5%. As médias dos tratamentos em cada variável foram comparadas pelo teste de Tukey. A contagem cloacal bacteriana de frangos de corte mostrou que o BthTx-I diminuiu a população microbiana sem comprometer o peso corporal, a morfologia intestinal ou causar danos histopatológico no fígado e rins. Concluiu-se que a toxina apresentou atividade in vivo, sendo uma alternativa para um melhor desempenho na produção de frangos de corte, pois agiu diminuindo a carga microbiana de bactérias potencialmente patogênicas na microbiota intestinal das aves e não causou danos musculares, hepáticos ou renais na dosagem avaliada.(AU)

Exploring the five-paced viper (Deinagkistrodon acutus) venom proteome by integrating a combinatorial peptide ligand library approach with shotgun LC-MS/MS

Abstract Background Snake venoms are complex mixtures of toxic proteins or peptides encoded by various gene families that function synergistically to incapacitate prey. In the present study, in order to unravel the proteomic repertoire of Deinagkistrodon acutus venom, some trace abundance components were analyzed. Methods Shotgun proteomic approach combined with shotgun nano-LC-ESI-MS/MS were employed to characterize the medically important D. acutus venom, after collected samples were enriched with the combinatorial peptide ligand library (CPLL). Results This avenue helped us find some trace components, undetected before, in D. acutus venom. The results indicated that D. acutus venom comprised 84 distinct proteins from 10 toxin families and 12 other proteins. These results are more than twice the number of venom components obtained from previous studies, which were only 29 distinct proteins obtained through RP-HPLC for the venom of the same species. The present results indicated that in D. acutus venom, the most abundant components (66.9%) included metalloproteinases, serine proteinases, and C-type lectin proteins; the medium abundant components (13%) comprised phospholipases A2 (PLA2) and 5-nucleotidases and nucleases; whereas least abundant components (6%) were aminopeptidases, L-amino acid oxidases (LAAO), neurotoxins and disintegrins; and the trace components. The last were undetected before the use of conventional shotgun proteomics combined with shotgun nano-LC-ESI-MS/MS, such as cysteine-rich secretory proteins Da-CRPa, phospholipases B-like 1, phospholipases B (PLB), nerve growth factors (NGF), glutaminyl-peptide cyclortransferases (QC), and vascular non-inflammatory molecules 2 (VNN2). Conclusion These findings demonstrated that the CPLL enrichment method worked well in finding the trace toxin proteins in D. acutus venom, in contrast with the previous venomic characterization of D. acutus by conventional LC-MS/MS. In conclusion, this approach combined with the CPLL enrichment was effective for allowing us to explore the hidden D. acutus venomic profile and extended the list of potential venom toxins.

Comparison of biological activities of Tityus pachyurus venom from two Colombian regions

Background: In the present study, we have tested whether specimens of the medically relevant scorpion Tityus pachyurus, collected from two climatically and ecologically different regions, differ in the biological activities of the venom. Methods: Scorpions were collected in Tolima and Huila, Colombia. Chemical profiles of the crude venom were obtained from 80 scorpions for each region, using SDS-PAGE and RP-HPLC. Assays for phospholipase A2, direct and indirect hemolytic, proteolytic, neuromuscular, antibacterial, and insecticidal activities were carried out. Results: The electrophoretic profiles of venom from the two regions showed similar bands of 6-14 kDa, 36-45 kDa, 65 kDa and 97 kDa. However, bands between 36 kDa and 65 kDa were observed with more intensity in venoms from Tolima, and a 95 kDa band occurred only in venoms from Huila. The chromatographic profile of the venoms showed differences in the intensity of some peaks, which could be associated with changes in the abundance of some components between both populations. Phospholipase A2 and hemolytic activities were not observable, whereas both venoms showed proteolytic activity towards casein. Insecticidal activity of the venoms from both regions showed significant variation in potency, the bactericidal activity was variable and low for both venoms. Moreover, no differences were observed in the neuromuscular activity assay. Conclusion: Our results reveal some variation in the activity of the venom between both populations, which could be explained by the ecological adaptations like differences in feeding, altitude and/or diverse predator exposure. However more in-depth studies are necessary to determine the drivers behind the differences in venom composition and activities.(AU)

Exploring the five-paced viper (Deinagkistrodon acutus) venom proteome by integrating a combinatorial peptide ligand library approach with shotgun LC-MS/MS

Snake venoms are complex mixtures of toxic proteins or peptides encoded by various gene families that function synergistically to incapacitate prey. In the present study, in order to unravel the proteomic repertoire of Deinagkistrodon acutus venom, some trace abundance components were analyzed. Methods Shotgun proteomic approach combined with shotgun nano-LC-ESI-MS/MS were employed to characterize the medically important D. acutus venom, after collected samples were enriched with the combinatorial peptide ligand library (CPLL). Results This avenue helped us find some trace components, undetected before, in D. acutus venom. The results indicated that D. acutus venom comprised 84 distinct proteins from 10 toxin families and 12 other proteins. These results are more than twice the number of venom components obtained from previous studies, which were only 29 distinct proteins obtained through RP-HPLC for the venom of the same species. The present results indicated that in D. acutus venom, the most abundant components (66.9%) included metalloproteinases, serine proteinases, and C-type lectin proteins; the medium abundant components (13%) comprised phospholipases A2 (PLA2) and 5'-nucleotidases and nucleases; whereas least abundant components (6%) were aminopeptidases, L-amino acid oxidases (LAAO), neurotoxins and disintegrins; and the trace components. The last were undetected before the use of conventional shotgun proteomics combined with shotgun nano-LC-ESI-MS/MS, such as cysteine-rich secretory proteins Da-CRPa, phospholipases B-like 1, phospholipases B (PLB), nerve growth factors (NGF), glutaminyl-peptide cyclortransferases (QC), and vascular non-inflammatory molecules 2 (VNN2). Conclusion These findings demonstrated that the CPLL enrichment method worked well in finding the trace toxin proteins in D. acutus venom, in contrast with the previous venomic characterization of D. acutus by conventional LC-MS/MS. In conclusion, this approach combined with the CPLL enrichment was effective for allowing us to explore the hidden D. acutus venomic profile and extended the list of potential venom toxins.(AU)

Exploring the five-paced viper (Deinagkistrodon acutus) venom proteome by integrating a combinatorial peptide ligand library approach with shotgun LC-MS/MS

Snake venoms are complex mixtures of toxic proteins or peptides encoded by various gene families that function synergistically to incapacitate prey. In the present study, in order to unravel the proteomic repertoire of Deinagkistrodon acutus venom, some trace abundance components were analyzed. Methods Shotgun proteomic approach combined with shotgun nano-LC-ESI-MS/MS were employed to characterize the medically important D. acutus venom, after collected samples were enriched with the combinatorial peptide ligand library (CPLL). Results This avenue helped us find some trace components, undetected before, in D. acutus venom. The results indicated that D. acutus venom comprised 84 distinct proteins from 10 toxin families and 12 other proteins. These results are more than twice the number of venom components obtained from previous studies, which were only 29 distinct proteins obtained through RP-HPLC for the venom of the same species. The present results indicated that in D. acutus venom, the most abundant components (66.9%) included metalloproteinases, serine proteinases, and C-type lectin proteins; the medium abundant components (13%) comprised phospholipases A2 (PLA2) and 5'-nucleotidases and nucleases; whereas least abundant components (6%) were aminopeptidases, L-amino acid oxidases (LAAO), neurotoxins and disintegrins; and the trace components. The last were undetected before the use of conventional shotgun proteomics combined with shotgun nano-LC-ESI-MS/MS, such as cysteine-rich secretory proteins Da-CRPa, phospholipases B-like 1, phospholipases B (PLB), nerve growth factors (NGF), glutaminyl-peptide cyclortransferases (QC), and vascular non-inflammatory molecules 2 (VNN2). Conclusion These findings demonstrated that the CPLL enrichment method worked well in finding the trace toxin proteins in D. acutus venom, in contrast with the previous venomic characterization of D. acutus by conventional LC-MS/MS. In conclusion, this approach combined with the CPLL enrichment was effective for allowing us to explore the hidden D. acutus venomic profile and extended the list of potential venom toxins.(AU)

Effects of Mlx-8, a phospholipase A2 from Brazilian coralsnake Micrurus lemniscatus venom, on muscarinic acetylcholine receptors in rat hippocampus

Abstract Background: Here, we described the presence of a neurotoxin with phospholipase A2 activity isolated from Micrurus lemniscatus venom (Mlx-8) with affinity for muscarinic acetylcholine receptors (mAChRs). Methods: The purification, molecular mass determination, partial amino acid sequencing, phospholipase A2 activity determination, inhibition of the binding of the selective muscarinic ligand [3H]QNB and inhibition of the total [3H]inositol phosphate accumulation in rat hippocampus of the Mlx-8 were determined. Results: Thirty-one fractions were collected from HPLC chromatography, and the Mlx-8 toxin was used in this work. The molecular mass of Mlx-8 is 13.628 Da. Edman degradation yielded the following sequence: NLYQFKNMIQCTNTRSWL-DFADYG-CYCGRGGSGT. The Mlx-8 had phospholipase A2 enzymatic activity. The pKi values were determined for Mlx-8 toxin and the M1 selective muscarinic antagonist pirenzepine in hippocampus membranes via [3H]QNB competition binding assays. The pKi values obtained from the analysis of Mlx-8 and pirenzepine displacement curves were 7.32 ± 0.15, n = 4 and 5.84 ± 0.18, n = 4, respectively. These results indicate that Mlx-8 has affinity for mAChRs. There was no effect on the inhibition ability of the [3H]QNB binding in hippocampus membranes when 1 µM Mlx-8 was incubated with 200 µM DEDA, an inhibitor of phospholipase A2. This suggests that the inhibition of the phospholipase A2 activity of the venom did not alter its ability to bind to displace [3H]QNB binding. In addition, the Mlx-8 toxin caused a blockade of 43.31 ± 8.86%, n = 3 and 97.42 ± 2.02%, n = 3 for 0.1 and 1 µM Mlx-8, respectively, on the total [3H]inositol phosphate content induced by 10 µM carbachol. This suggests that Mlx-8 inhibits the intracellular signaling pathway linked to activation of mAChRs in hippocampus. Conclusion: The results of the present work show, for the first time, that muscarinic receptors are also affected by the Mlx-8...(AU)

Identification and characterization of the first endogenous phospholipase A2 inhibitor from a non-venomous tropical snake, Boa constrictor (Serpentes: Boidae)

Abstract Background: Endogenous phospholipase A2 inhibitors from snake blood (sbPLIs) have been isolated from several species around the world, with the primary function of self-protection against the action of toxic phospholipases A2. In American snakes, sbPLIs were solely described in pit vipers, in which the natural protection role is justified. In this study, we described a sbPLI in Boa constrictor (popularly known as jiboia), a non-venomous snake species from America. Methods: PLA2 inhibitory activity was tested in the blood plasma of B. constrictor using C. d. terrificus venom as the enzyme source. Antibodies developed against CNF, a sbγPLI from Crotalus durissus terrificus, were used to investigate the presence of homologues in the blood plasma of B. constrictor. A CNF-like molecule with a PLA2 inhibitory activity was purified by column chromatography. The encoding gene for the inhibitor was cloned from B. constrictor liver tissue. The DNA fragment was cloned, purified and sequenced. The deduced primary sequence of interest was aligned with known sbγPLIs from the literature. Results: The blood plasma of B. constrictor displayed PLA2 inhibitory activity. A CNF-like molecule (named BcNF) was identified and purified from the blood plasma of B. constrictor. Basic properties such as molecular mass, composing amino acids, and pI were comparable, but BcNF displayed reduced specific activity in PLA2 inhibition. BcNF showed highest identity scores (ISs) with sbγPLIs from pit vipers from Latin America (90-100%), followed by gamma inhibitors from Asian viperid (80-90%). ISs below 70% were obtained for BcNF and non-venomous species from Asia. Conclusion: A functional sbγPLI (BcNF) was described in the blood plasma of B. constrictor. BcNF displayed higher primary identity with sbγPLIs from Viperidae than to sbγPLIs from non-venomous species from Asia. The physiological role played by sbγPLIs in non-venomous snake species remains to be understood. Further investigation is needed.(AU)

Role of crotoxin in coagulation: novel insights into anticoagulant mechanisms and impairment of inflammation-induced coagulation

Snake venom phospholipases A2 (svPLA2) are biologically active toxins, capable of triggering and modulating a wide range of biological functions. Among the svPLA2s, crotoxin (CTX) has been in the spotlight of bioprospecting research due to its role in modulating immune response and hemostasis. In the present study, novel anticoagulant mechanisms of CTX, and the modulation of inflammation-induced coagulation were investigated. Methods: CTX anticoagulant activity was evaluated using platelet poor plasma (PPP) and whole blood (WB), and also using isolated coagulation factors and complexes. The toxin modulation of procoagulant and pro-inflammatory effects was evaluated using the expression of tissue factor (TF) and cytokines in lipopolysaccharide (LPS)-treated peripheral blood mononuclear cells (PBMC) and in WB. Results: The results showed that CTX impaired clot formation in both PPP and WB, and was responsible for the inhibition of both intrinsic (TF/factor VIIa) and extrinsic (factor IXa/factor VIIIa) tenase complexes, but not for factor Xa and thrombin alone. In addition, the PLA2 mitigated the prothrombinase complex by modulating the coagulation phospholipid role in the complex. In regards to the inflammation-coagulation cross talk, the toxin was capable of reducing the production of the pro-inflammatory cytokines IL-1β, IL-6 and TNF-α, and was followed by decreased levels of TF and procoagulant activity from LPS-treated PBMC either isolated or in WB. Conclusion: The results obtained in the present study recognize the toxin as a novel medicinal candidate to be applied in inflammatory diseases with coagulation disorders.(AU)

Role of crotoxin in coagulation: novel insights into anticoagulant mechanisms and impairment of inflammation-induced coagulation

Snake venom phospholipases A2 (svPLA2) are biologically active toxins, capable of triggering and modulating a wide range of biological functions. Among the svPLA2s, crotoxin (CTX) has been in the spotlight of bioprospecting research due to its role in modulating immune response and hemostasis. In the present study, novel anticoagulant mechanisms of CTX, and the modulation of inflammation-induced coagulation were investigated. Methods: CTX anticoagulant activity was evaluated using platelet poor plasma (PPP) and whole blood (WB), and also using isolated coagulation factors and complexes. The toxin modulation of procoagulant and pro-inflammatory effects was evaluated using the expression of tissue factor (TF) and cytokines in lipopolysaccharide (LPS)-treated peripheral blood mononuclear cells (PBMC) and in WB. Results: The results showed that CTX impaired clot formation in both PPP and WB, and was responsible for the inhibition of both intrinsic (TF/factor VIIa) and extrinsic (factor IXa/factor VIIIa) tenase complexes, but not for factor Xa and thrombin alone. In addition, the PLA2 mitigated the prothrombinase complex by modulating the coagulation phospholipid role in the complex. In regards to the inflammation-coagulation cross talk, the toxin was capable of reducing the production of the pro-inflammatory cytokines IL-1β, IL-6 and TNF-α, and was followed by decreased levels of TF and procoagulant activity from LPS-treated PBMC either isolated or in WB. Conclusion: The results obtained in the present study recognize the toxin as a novel medicinal candidate to be applied in inflammatory diseases with coagulation disorders.(AU)

Identification and characterization of the first endogenous phospholipase A2 inhibitor from a non-venomous tropical snake, Boa constrictor (Serpentes: Boidae)

Background:Endogenous phospholipase A2 inhibitors from snake blood (sbPLIs) have been isolated from several species around the world, with the primary function of self-protection against the action of toxic phospholipases A2. In American snakes, sbPLIs were solely described in pit vipers, in which the natural protection role is justified. In this study, we described a sbPLI in Boa constrictor (popularly known as jiboia), a non-venomous snake species from America.Methods:PLA2 inhibitory activity was tested in the blood plasma of B. constrictor using C. d. terrificus venom as the enzyme source. Antibodies developed against CNF, a sbγPLI from Crotalus durissus terrificus, were used to investigate the presence of homologues in the blood plasma of B. constrictor. A CNF-like molecule with a PLA2 inhibitory activity was purified by column chromatography. The encoding gene for the inhibitor was cloned from B. constrictor liver tissue. The DNA fragment was cloned, purified and sequenced. The deduced primary sequence of interest was aligned with known sbγPLIs from the literature.Results:The blood plasma of B. constrictor displayed PLA2 inhibitory activity. A CNF-like molecule (named BcNF) was identified and purified from the blood plasma of B. constrictor. Basic properties such as molecular mass, composing amino acids, and pI were comparable, but BcNF displayed reduced specific activity in PLA2 inhibition. BcNF showed highest identity scores (ISs) with sbγPLIs from pit vipers from Latin America (90-100%), followed by gamma inhibitors from Asian viperid (80-90%). ISs below 70% were obtained for BcNF and non-venomous species from Asia.Conclusion:A functional sbγPLI (BcNF) was described in the blood plasma of B. constrictor. BcNF displayed higher primary identity with sbγPLIs from Viperidae than...(AU)

Geographic variation of individual venom profile of Crotalus durissus snakes

South American rattlesnakes are represented in Brazil by a single species, Crotalus durissus, which has public health importance due to the severity of its envenomation and to its wide geographical distribution. The species is subdivided into several subspecies, but the current classification is controversial. In Brazil, the venoms of C. d. terrificus and C. d. collilineatus are used for hyperimmunization of horses for antivenom production, even though the distinction of these two subspecies are mostly by their geographical distribution. In this context, we described a comparative compositional and functional characterization of individual C. d. collilineatus and C. d. terrificus venoms from three Brazilian states. Methods: We compared the compositional patterns of C. d. terrificus and C. d. collilineatus individual venoms by 1-DE and RP-HPLC. For functional analyzes, the enzymatic activities of PLA2, LAAO, and coagulant activity were evaluated. Finally, the immunorecognition of venom toxins by the crotalic antivenom produced at Butantan Institute was evaluated using Western blotting. Results: The protein profile of individual venoms from C. d. collilineatus and C. d. terrificus showed a comparable overall composition, despite some intraspecific variation, especially regarding crotamine and LAAO. Interestingly, HPLC analysis showed a geographic pattern concerning PLA2. In addition, a remarkable intraspecific variation was also observed in PLA2, LAAO and coagulant activities. The immunorecognition pattern of individual venoms from C. d. collilineatus and C. d. terrificus by crotalic antivenom produced at Butantan Institute was similar. Conclusions: The results highlighted the individual variability among the venoms of C. durissus ssp. specimens. Importantly, our data point to a geographical variation of C. durissus ssp. venom profile, regardless of the subspecies, as evidenced by PLA2 isoforms complexity, which may explain the increase in venom neurotoxicity from Northeastern through Southern Brazil reported for the species.(AU)

Biochemical characterization and cytotoxic effect of the skin secretion from the red-spotted Argentina frog Argenteohyla siemersi (Anura: Hylidae)

Argenteohyla siemersi (red-spotted Argentina frog) is a casque-headed tree frog species belonging to the Hylidae family. This species has a complex combination of anti-predator defense mechanisms that include a highly lethal skin secretion. However, biochemical composition and biological effects of this secretion have not yet been studied. Methods: The A. siemersi skin secretion samples were analyzed by mass spectrometry and chromatographic analysis (MALDI-TOF/MS, RP-HPLC and GC-MS). Proteins were also studied by SDS-PAGE. Among the biological activities evaluated, several enzymatic activities (hemolytic, phospholipase A2, clotting, proteolytic and amidolytic) were assessed. Furthermore, the cytotoxic activity (cytolysis and fluorescence staining) was evaluated on myoblasts of the C2C12 cell line. Results: The MALDI-TOF/MS analysis identified polypeptides and proteins in the aqueous solution of A. siemersi skin secretion. SDS-PAGE revealed the presence of proteins with molecular masses from 15 to 55 kDa. Steroids, but no alkaloids or peptides (less than 5 KDa), were detected using mass spectrometry. Skin secretion revealed the presence of lipids in methanolic extract, as analyzed by CG-MS. This secretion showed hemolytic and phospholipase A2 activities, but was devoid of amidolytic, proteolytic or clotting activities. Moreover, dose-dependent cytotoxicity in cultured C2C12 myoblasts of the skin secretion was demonstrated. Morphological analysis, quantification of lactate dehydrogenase release and fluorescence staining indicated that the cell death triggered by this secretion involved necrosis. Conclusions: Results presented herein evidence the biochemical composition and biological effects of A. siemersi skin secretion and contribute to the knowledge on the defense mechanisms of casque-headed frogs.(AU)

Proteomics and antivenom immunoprofiling of Russell's viper (Daboia siamensis) venoms from Thailand and Indonesia

The Eastern Russell's viper, Daboia siamensis, is a WHO Category 1 medically important venomous snake. It has a wide but disjunct distribution in Southeast Asia. The specific antivenom, D. siamensis Monovalent Antivenom (DsMAV-Thailand) is produced in Thailand but not available in Indonesia, where a heterologous trivalent antivenom, Serum Anti Bisa Ular (SABU), is used instead. This study aimed to investigate the geographical venom variation of D. siamensis from Thailand (Ds-Thailand) and Indonesia (Ds-Indonesia), and the immunorecognition of the venom proteins by antivenoms. Methods: The venom proteins were decomplexed with reverse-phase high-performance liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by in-solution tryptic digestion, nano-liquid chromatography-tandem mass spectrometry and protein identification. The efficacies of DsMAV-Thailand and SABU in binding the various venom fractions were assessed using an enzyme-linked immunosorbent assay optimized for immunorecognition profiling. Results: The two most abundant protein families in Ds-Thailand venom are phospholipase A2 (PLA2) and Kunitz-type serine protease inhibitor (KSPI). Those abundant in Ds-Indonesia venom are PLA2 and serine protease. KSPI and vascular endothelial growth factor were detected in Ds-Thailand venom, whereas L-amino acid oxidase and disintegrin were present in Ds-Indonesia venom. Common proteins shared between the two included snaclecs, serine proteases, metalloproteinases, phosphodiesterases, 5'nucleotidases and nerve growth factors at varying abundances. DsMAV-Thailand exhibited strong immunorecognition of the major protein fractions in both venoms, but low immunoreactivity toward the low molecular weight proteins e.g. KSPI and disintegrins. On the other hand, SABU was virtually ineffective in binding all fractionated venom proteins. Conclusion: D. siamensis venoms from Thailand and Indonesia varied geographically in the protein subtypes and abundances. The venoms, nevertheless, shared conserved antigenicity that allowed effective immunorecognition by DsMAV-Thailand but not by SABU, consistent with the neutralization efficacy of the antivenoms. A specific, appropriate antivenom is needed in Indonesia to treat Russell's viper envenomation.(AU)

Venom complexity of Bothrops atrox (common lancehead) siblings

Variability in snake venoms is a well-studied phenomenon. However, sex-based variation of Bothrops atrox snake venom using siblings is poorly investigated. Bothrops atrox is responsible for the majority of snakebite accidents in the Brazilian Amazon region. Differences in the venom composition of Bothrops genus have been linked to several factors such as ontogeny, geographical distribution, prey preferences and sex. Thus, in the current study, venom samples of Bothrops atrox male and female siblings were analyzed in order to compare their biochemical and biological characteristics. Methods: Venoms were collected from five females and four males born from a snake captured from the wild in São Bento (Maranhão, Brazil), and kept in the Laboratory of Herpetology of Butantan Intitute. The venoms were analyzed individually and as a pool of each gender. The assays consisted in protein quantification, 1-DE, mass spectrometry, proteolytic, phospholipase A2, L-amino acid oxidase activities, minimum coagulant dose upon plasma, minimum hemorrhagic dose and lethal dose 50%. Results: Electrophoretic profiles of male's and female's venom pools were quite similar, with minor sex-based variation. Male venom showed higher LAAO, PLA2 and hemorrhagic activities, while female venom showed higher coagulant activity. On the other hand, the proteolytic activities did not show statistical differences between pools, although some individual variations were observed. Meanwhile, proteomic profile revealed 112 different protein compounds; of which 105 were common proteins of female's and male's venom pools and seven were unique to females. Despite individual variations, lethality of both pools showed similar values. Conclusion: Although differences between female and male venoms were observed, our results show that individual variations are significant even between siblings, highlighting that biological activities of venoms and its composition are influenced by other factors beyond gender.(AU)

Proteomics and antivenom immunoprofiling of Russell's viper (Daboia siamensis) venoms from Thailand and Indonesia

Background The Eastern Russells viper, Daboia siamensis, is a WHO Category 1 medically important venomous snake. It has a wide but disjunct distribution in Southeast Asia. The specific antivenom, D. siamensis Monovalent Antivenom (DsMAV-Thailand) is produced in Thailand but not available in Indonesia, where a heterologous trivalent antivenom, Serum Anti Bisa Ular (SABU), is used instead. This study aimed to investigate the geographical venom variation of D. siamensis from Thailand (Ds-Thailand) and Indonesia (Ds-Indonesia), and the immunorecognition of the venom proteins by antivenoms. Methods: The venom proteins were decomplexed with reverse-phase high-performance liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by in-solution tryptic digestion, nano-liquid chromatography-tandem mass spectrometry and protein identification. The efficacies of DsMAV-Thailand and SABU in binding the various venom fractions were assessed using an enzyme-linked immunosorbent assay optimized for immunorecognition profiling. Results: The two most abundant protein families in Ds-Thailand venom are phospholipase A2 (PLA2) and Kunitz-type serine protease inhibitor (KSPI). Those abundant in Ds-Indonesia venom are PLA2 and serine protease. KSPI and vascular endothelial growth factor were detected in Ds-Thailand venom, whereas L-amino acid oxidase and disintegrin were present in Ds-Indonesia venom. Common proteins shared between the two included snaclecs, serine proteases, metalloproteinases, phosphodiesterases, 5nucleotidases and nerve growth factors at varying abundances. DsMAV-Thailand exhibited strong immunorecognition of the major protein fractions in both venoms, but low immunoreactivity toward the low molecular weight proteins e.g. KSPI and disintegrins. On the other hand, SABU was virtually ineffective in binding all fractionated venom proteins. Conclusion: D. siamensis venoms from Thailand and Indonesia varied...(AU)

Effects of Mlx-8, a phospholipase A2 from Brazilian coralsnake Micrurus lemniscatus venom, on muscarinic acetylcholine receptors in rat hippocampus

Here, we described the presence of a neurotoxin with phospholipase A2 activity isolated from Micrurus lemniscatus venom (Mlx-8) with affinity for muscarinic acetylcholine receptors (mAChRs). Methods: The purification, molecular mass determination, partial amino acid sequencing, phospholipase A2 activity determination, inhibition of the binding of the selective muscarinic ligand [3H]QNB and inhibition of the total [3H]inositol phosphate accumulation in rat hippocampus of the Mlx-8 were determined. Results: Thirty-one fractions were collected from HPLC chromatography, and the Mlx-8 toxin was used in this work. The molecular mass of Mlx-8 is 13.628 Da. Edman degradation yielded the following sequence: NLYQFKNMIQCTNTRSWL-DFADYG-CYCGRGGSGT. The Mlx-8 had phospholipase A2 enzymatic activity. The pKi values were determined for Mlx-8 toxin and the M1 selective muscarinic antagonist pirenzepine in hippocampus membranes via [3H]QNB competition binding assays. The pKi values obtained from the analysis of Mlx-8 and pirenzepine displacement curves were 7.32 ± 0.15, n = 4 and 5.84 ± 0.18, n = 4, respectively. These results indicate that Mlx-8 has affinity for mAChRs. There was no effect on the inhibition ability of the [3H]QNB binding in hippocampus membranes when 1 µM Mlx-8 was incubated with 200 µM DEDA, an inhibitor of phospholipase A2. This suggests that the inhibition of the phospholipase A2 activity of the venom did not alter its ability to bind to displace [3H]QNB binding. In addition, the Mlx-8 toxin caused a blockade of 43.31 ± 8.86%, n = 3 and 97.42 ± 2.02%, n = 3 for 0.1 and 1 µM Mlx-8, respectively, on the total [3H]inositol phosphate content induced by 10 µM carbachol. This suggests that Mlx-8 inhibits the intracellular signaling pathway linked to activation of mAChRs in hippocampus. Conclusion: The results of the present work show, for the first time, that muscarinic receptors are also affected by the Mlx-8 toxin, a muscarinic ligand with phospholipase A2 characteristics, obtained from the venom of the Elapidae snake Micrurus lemniscatus, since this toxin was able to compete with muscarinic ligand [3H]QNB in hippocampus of rats. In addition, Mlx-8 also blocked the accumulation of total [3H]inositol phosphate induced by muscarinic agonist carbachol. Thus, Mlx-8 may be a new pharmacological tool for examining muscarinic cholinergic function.(AU)

Subproteome of Lachesis muta rhombeata venom and preliminary studies on LmrSP-4, a novel snake venom serine proteinase

Lachesis muta rhombeata is one of the venomous snakes of medical importance in Brazil whose envenoming is characterized by local and systemic effects which may produce even shock and death. Its venom is mainly comprised of serine and metalloproteinases, phospholipases A2 and bradykinin-potentiating peptides. Based on a previously reported fractionation of L. m. rhombeata venom (LmrV), we decided to perform a subproteome analysis of its major fraction and investigated a novel component present in this venom. Methods: LmrV was fractionated through molecular exclusion chromatography and the main fraction (S5) was submitted to fibrinogenolytic activity assay and fractionated by reversed-phase chromatography. The N-terminal sequences of the subfractions eluted from reversed-phase chromatography were determined by automated Edman degradation. Enzyme activity of LmrSP-4 was evaluated upon chromogenic substrates for thrombin (S-2238), plasma kallikrein (S-2302), plasmin and streptokinase-activated plasminogen (S-2251) and Factor Xa (S-2222) and upon fibrinogen. All assays were carried out in the presence or absence of possible inhibitors. The fluorescence resonance energy transfer substrate Abz-KLRSSKQ-EDDnp was used to determine the optimal conditions for LmrSP-4 activity. Molecular mass of LmrSP-4 was determined by MALDI-TOF and digested peptides after trypsin and Glu-C treatments were analyzed by high resolution MS/MS using different fragmentation modes. Results: Fraction S5 showed strong proteolytic activity upon fibrinogen. Its fractionation by reversed-phase chromatography gave rise to 6 main fractions (S5C1-S5C6). S5C1-S5C5 fractions correspond to serine proteinases whereas S5C6 represents a C-type lectin. S5C4 (named LmrSP-4) had its N-terminal determined by Edman degradation up to the 53rd amino acid residue and was chosen for characterization studies. LmrSP-4 is a fibrinogenolytic serine proteinase with high activity against S-2302, being inhibited by PMSF and benzamidine, but not by 1,10-phenantroline. In addition, this enzyme exhibited maximum activity within the pH range from neutral to basic and between 40 and 50 °C. About 68% of the LmrSP-4 primary structure was covered, and its molecular mass is 28,190 Da. Conclusions: Novel serine proteinase isoforms and a lectin were identified in LmrV. Additionally, a kallikrein-like serine proteinase that might be useful as molecular tool for investigating bradykinin-involving process was isolated and partially characterized.(AU)