Snake venomics of the South and Central American Bushmasters. Comparison of the toxin composition of Lachesis muta gathered from proteomic versus transcriptomic analysis

Development of a neutralizing monoclonal antibody targeting Bothrops atrox venom metalloproteinases

Snakebites are classified as a neglected tropical disease by the World Health Organization. In South America's tropical rainforests, Bothrops genus, particularly Bothrops atrox, is responsible for most incidents. Severe local effects, such as hemorrhage, are primarily caused by snake venom metalloproteinases (SVMPs), which are not fully neutralized by conventional therapy. Here, we report the production of a neutralizing monoclonal antibody (mAb) against the hemorrhagic activity of B. atrox venom metalloproteinases. mAbs were produced by immunization of BALB/c mice using the B. atrox venom (BaV). The resulting hybridomas were screened by ELISA using BaV as antigen. The selected clone 4H4D11 (mAb-BaSVMP) showed cross-reactivity with other medically important species of Bothrops snakes in Brazil and Peru. Western blot assays revealed that the produced mAb binds to proteins with molecular masses of approximately 50 kDa and 20 kDa in BaV and recognizes native Atroxlysin-III and Atroxlysin-I by ELISA. mAb-BaSVMP did not bind to a cellulose membrane containing the primary sequence of a metalloproteinase, suggesting that it may recognize a conformational epitope. Additionally, mAb-BaSVMP neutralizes the in vivo hemorrhagic activity caused by BaV in mice. These results highlight the potential usefulness of mAb-BaSVMP for developing effective antivenoms for passive immunotherapy against bothropic envenomation.

Consistent Killers: Conservation of Thrombin-Like Action on Fibrinogen by Bushmaster (Lachesis Species) Venoms Underpins Broad Antivenom Cross-Reactivities

Snakebite represents a significant public health challenge in Central and South America, with Lachesis (Bushmaster) species posing unique clinical challenges due to their severe envenomation effects arising from a combination of potent venom and copious venom yields. Using in vitro coagulation assays, we analyzed the coagulotoxic venom effects from four distinct localities: L. muta from Surinam and French Guiana and L. stenophrys from Costa Rica and Panama. This study examined the venom's impact on human plasma and fibrinogen and evaluated the efficacy of two regionally available antivenoms (PoliVal-ICP and Antivipmyn-Tri) in neutralizing the pathophysiological effects. Our results demonstrated a remarkable consistency in the pseudo-procoagulant venom activity (also known as: thrombin-like) across different species and localities. Antivenom efficacy testing revealed that both the PoliVal-ICP and Antivipmyn-Tri antivenoms effectively neutralized the venom effects across localities for both species, with the ICP antivenom showing the highest neutralization capacity. These toxicology findings highlight the biochemical conservation of venom composition across Lachesis species which underpins effective cross-neutralization in antivenom treatment.

Snake venom galactoside-binding lectin from Bothrops jararacussu: Special role in leukocytes activation and function

Snake venom galactoside-binding lectins (SVgalLs) comprise a group of toxins with the ability to bind specifically, reversibly, and non-covalently to galactose-containing carbohydrates in a Ca2+-dependent manner. Several SVgalLs have been identified and isolated from Bothrops snake venoms, presenting highly similar structures and biological functions. BjcuL is a galactoside binding C-type lectin isolated from the venom of South America Bothrops jararacussu and consists of the most investigated lectin. Previous studies have deeply investigated the participation of BjcuL in physiopathological events, especially involving its participation in inflammation. The lectin has been demonstrated as a pro-inflammatory agent, capable of triggering inflammatory events related to local and systemic leukocyte function. This activity is mediated by its binding to galactose-containing glycans on the cell surface to trigger different intracellular signaling and promote functional activation as rolling, adhesion, and migration of leukocytes, production of inflammatory mediators, and a killing profile of phagocytes. Furthermore, this review highlights not only the current understanding of snake venom lectins in pathophysiology and inflammation research but also explores potential future advancements, including the application of emerging technologies such as structural bioinformatics, high-throughput screening, and advanced omics approaches to uncover novel therapeutic targets and biotechnological applications.

Ability of brazilian Bothrops-Lachesis-Crotalus antivenom in neutralizing some biological activities of Crotalus durissus ruruima rattlesnake venom

We evaluated the efficacy of freeze-dried Bothrops-Lachesis-Crotalus antivenom and liquid Crotalus antivenoms to neutralize Crotalus durissus ruruima (Cdr) venom (Roraima, Brazil) comparing with C. d. terrificus (Cdt) venom. Lethal and phospholipase A2 activities were similar between both spp. Crotamine was negative and individual Cdr venoms induced hemorrhage in mice. It was lower coagulant than Cdt venom. Only Bothrops-Lachesis-Crotalus antivenom neutralized all biological activities evaluated, suggesting that it could be used in snakebites in this region.

An alternative method for comparing hemorrhagic activity of snake venoms following one of the 3R's principles

Venom-induced hemorrhage analysis usually is performed by Minimum Hemorrhagic Dose (MHD), however a similar method can be used to compare venoms with fewer laboratory animals. Our work compared the MHD of five different venoms, with the size of hemorrhagic spot, finding good correlations in the results. Considering the 3Rs principle, we propose the use of the hemorrhagic spot method to compare hemorrhagic activity of snake venoms, rather than using the MHD method, since the first one needs 5 times less animals than the other.

Identification of antigenic proteins from the venom of Malaysian snakes using immunoprecipitation assay and tandem mass spectrometry (LC-MS/MS)

Snake envenomation poses a significant risk to Malaysians and country visitors. Malaysia witnesses an estimated 650 snake bites per 100,000 population annually. The primary treatment for snake envenomation involves administering antivenom derived from horses, despite its drawbacks, such as anaphylactic reactions and serum sickness. Identifying the venom proteome is crucial for understanding and predicting the clinical implications of envenomation and developing effective treatments targeting specific venom proteins. In this study, we employ an immunoprecipitation assay followed by LC-MS/MS to identify antigenic proteins in five common venomous snakes in Malaysia compassing of two families which are pit vipers, (Calloselasma rhodostoma and Cryptelytrops purpureomaculatus) and cobras (Ophiophagus hannah, Naja kaouthia, and Naja sumatrana). The immunoprecipitation assay utilises a 2 % agarose gel, allowing antigenic proteins to diffuse and bind with antibodies in the antivenom. The antivenom utilised in this research was procured from the Queen Saovabha Memorial Institute (QSMI), Thailand, including king cobra antivenom (KCAV), cobra antivenom (CAV), Malayan pit viper antivenom (MPAV), Russell's viper antivenom (RPAV), hematopolyvalent antivenom (HPAV), neuropolyvalent antivenom (NPAV), banded krait antivenom (BKAV), and Malayan krait antivenom (MKAV). The protein identified through these interactions which are exclusive to the cobras are three-finger toxins (3FTXs) while snake C-type lectins (Snaclecs) are unique to the pit vipers. Common protein that are present in both families are L-amino acid oxidase (LAAO), Phospholipase A2 (PLA2), and snake venom metalloproteinase (SVMP). Identifying these proteins is vital for formulating a broad-spectrum antivenom applicable across multiple species.

Understanding Why Homeopathic Medicines are Used for Menopause: Searching for Insights into Neuroendocrine Features

BACKGROUND

Menopause is a physiological event that marks the end of a woman's reproductive stage in life. Vasomotor symptoms and changes in mood are among its most important effects. Homeopathy has been used for many years in treating menopausal complaints, though clinical and pre-clinical research in this field is limited. Homeopathy often bases its prescription on neuropsychiatric symptoms, but it is unknown if homeopathic medicines (HMs) exert a neuroendocrine effect that causes an improvement in vasomotor symptoms and mood during menopause.

OBJECTIVES

The study's objectives were to address the pathophysiological changes of menopause that could help in the understanding of the possible effect of HMs at a neuroendocrine level, to review the current evidence for two of the most frequently prescribed HMs for menopause (Lachesis mutus and Sepia officinalis), and to discuss the future directions of research in this field.

METHODS

An extensive literature search for the pathophysiologic events of menopause and depression, as well as for the current evidence for HMs in menopause and depression, was performed.

RESULTS

Neuroendocrine changes are involved in the pathophysiology of vasomotor symptoms and changes in mood during menopause. Gonadal hormones modulate neurotransmitter systems. Both play a role in mood disorders and temperature regulation. It has been demonstrated that Gelsemium sempervirens, Ignatia amara and Chamomilla matricaria exert anxiolytic effects in rodent models. Lachesis mutus and Sepia officinalis are frequently prescribed for important neuropsychiatric and vasomotor symptoms. Dopamine, a neurotransmitter involved in mood, is among the constituents of the ink of the common cuttlefish, Sepia officinalis.

CONCLUSION

Based on all the pathophysiologic events of menopause and the improvement in menopausal complaints that certain HMs show in daily practice, these medicines might have a direct or indirect neuroendocrine effect in the body, possibly triggered via an as-yet unidentified biological mechanism. Many unanswered questions in this field require further pre-clinical and clinical research.

Biochemical and toxicological profiles of venoms from an adult female South American bushmaster (Lachesis muta rhombeata) and her offspring

In this work, we compared the biochemical and toxicological profiles of venoms from an adult female specimen of Lachesis muta rhombeata (South American bushmaster) and her seven offspring born in captivity, based on SDS-PAGE, RP-HPLC, enzymatic, coagulant, and hemorrhagic assays. Although adult and juvenile venoms showed comparable SDS-PAGE profiles, juveniles lacked some chromatographic peaks compared with adult venom. Adult venom had higher proteolytic (caseinolytic) activity than juvenile venoms (p < 0.05), but there were no significant inter-venom variations in the esterase, PLA2, phosphodiesterase and L-amino acid oxidase (LAAO) activities, although the latter activity was highly variable among the venoms. Juveniles displayed higher coagulant activity on human plasma, with a minimum coagulant dose ∼42% lower than the adult venom (p < 0.05), but there were no age-related differences in thrombin-like activity. Adult venom was more fibrinogenolytic (based on the rate of fibrinogen chain degradation) and hemorrhagic than juvenile venoms (p < 0.05). The effective dose of Bothrops/Lachesis antivenom (produced by the Instituto Butantan) needed to neutralize the coagulant activity was ∼57% greater for juvenile venoms (p < 0.05), whereas antivenom did not attenuate the thrombin-like activity of juvenile and adult venoms. Antivenom significantly reduced the hemorrhagic activity of adult venom (400 μg/kg, i. d.), but not that of juvenile venoms. Overall, these data indicate a compositional and functional ontogenetic shift in L. m. rhombeata venom.

Structural, biochemical and immunochemical characterization of an acidic phospholipase A2 from Lachesis acrochorda (Viperidae: Crotalinae) venom

Viperids of the genus Lachesis, also known as bushmasters, are capable of injecting great amounts of venom that cause severe envenomation incidents. Since phospholipases type A2 are mainly involved in edema and myonecrosis within the snakebite sites, in this work, the isolation, amino acid sequence and biochemical characterization of the first phospholipase type A2 from the venom of Lachesis acrochorda, named Lacro_PLA2, is described. Lacro_PLA2 is an acidic aspartic 49 calcium-dependent phospholipase A2 with 93% similarity to the L. stenophrys phospholipase. Lacro_PLA2 has a molecular mass of 13,969.7 Da and an experimental isoelectric point around 5.3. A combination of N-terminal Edman degradation and MS/MS spectrometry analyses revealed that Lacro_PLA2 contains 122 residues including 14 cysteines that form 7 disulfide bridges. A predicted 3D model shows a high resemblance to other viperid phospholipases. Nevertheless, immunochemical and phospholipase neutralization tests revealed a notorious level of immunorecognition of the isolated protein by two polyclonal antibodies from viperids from different genus, which suggest that Lacro_PLA2 resembles more to bothropic phospholipases. Lacro_PLA2 also showed significantly high edema activity when was injected into mice; so, it could be an alternative antigen in the development of antibodies against toxins of this group of viperids, seeking to improve commercial polyclonal antivenoms.

Unveiling the peptidome diversity of Lachesismuta snake venom: Discovery of novel fragments of metalloproteinase, l-amino acid oxidase, and bradykinin potentiating peptides

Snake venoms are known to be major sources of peptides with different pharmacological properties. In this study, we comprehensively explored the venom peptidomes of three specimens of Lachesismuta, the largest venomous snake in South America, using mass spectrometry techniques. The analysis revealed 19 main chromatographic peaks common to all specimens. A total of 151 peptides were identified, including 69 from a metalloproteinase, 58 from the BPP-CNP precursor, and 24 from a l-amino acid oxidase. To our knowledge, 126 of these peptides were reported for the first time in this work, including a new SVMP-derived peptide fragment, Lm-10a. Our findings highlight the dynamic nature of toxin maturation in snake venoms, driven by proteolytic processing, post-translational modifications, and cryptide formation.

The Colombian bushmasters Lachesis acrochorda (García, 1896) and Lachesis muta (Linnaeus, 1766): Snake species, venoms, envenomation, and its management

In Colombia, there are two species of bushmaster snakes, Lachesis acrochorda, which is distributed mainly in the west of the country (in the Choco region), and Lachesis muta in the southeast (in the Amazon and Orinoquia region), whose presence has been reduced due to the destruction of their habitats. Captive maintenance is challenging, making it difficult to obtain their venom for study and antivenom manufacturing. They are the largest vipers in the world. The occurrence of human envenomation is quite rare, but when it occurs, it is associated with high mortality. Bushmaster venom is necrotizing, hemorrhagic, myotoxic, hemolytic, and cardiovascular depressant. Due to the presence of bradycardia, hypotension, emesis, and diarrhea in some patients (Lachesis syndrome), the possibility of a vagal or cholinergic effect is raised. The treatment of envenomation is hindered by the scarcity of antivenom and the need to use high doses. A review of the most relevant biological and medical aspects of bushmaster snakes is presented, mainly for those occurring in Colombia, to facilitate their recognition and raise awareness about the need for special attention to improve their conservation and advance scientific knowledge, in particular, about their venom.

Rhomb-I, a P–I metalloproteinase from Lachesis muta rhombeata venom degrades vessel extra cellular matrix components and impairs platelet aggregation

Rhomb-I, a 23-kDa metalloproteinase was isolated from L. m. rhombeata venom. Its dimethylcasein proteolysis was abolished by metal chelators, and slightly enhanced by Ca²⁺ and Mg²⁺ ions, but inhibited by Co²⁺, Zn²⁺ and α2-macroglobulin. In aqueous solution, rhomb-I autoproteolyzed to a 20- and 11-kDa fragments at 37 °C. The amino acid sequence showed high homology with other snake venom metalloproteinases. Rhomb-I causes hemorrhage that may be ascribed to hydrolysis of essential basement membrane, extracellular matrix and plasma proteins. It preferentially cleaves the α-chains of fibrin (ogen). Rhomb-I inhibited convulxin- and von Willebrand factor (vWF)-induced aggregation on human platelets without significant effect on collagen-stimulated aggregation or other effectors. It digests vWF into a low-molecular-mass multimers of vWF and a rvWF-A1 domain to a 27-kDa fragment as revealed by western blotting with mouse anti-rvWF A1-domain IgG. Incubation of platelets with rhomb-I resulted in adhesion to and cleavage of platelet receptors glycoprotein (GP)Ibα and GPVI to release a 55-kDa soluble form. Both membrane glycoproteins GPIbα that binds vWF, together with GPVI which binds collagen, play a key role in mediating platelet adhesion/activation and can initiate (patho)physiological thrombus formation. Conclusions: rhomb-I is implicated in the pathophysiology of Lachesis envenoming by disrupting vasculature, hemostasis and platelet aggregation through impairing vWF-GPIb axis and blocking GPVI-collagen binding.

Proteomic and functional analyses of Lachesis acrochorda snake venom from the Valle del Cauca Department of Colombia

Lachesis acrochorda envenomation has a lethality rate of approximately 90%. Despite its high lethality, little is known about its local and systemic effects and its relationship with its protein content. Thus, to increase knowledge of L. acrochorda snake venom from the Southwestern ecoregion of Colombia, we developed a proteomic analysis using a "bottom-up shotgun proteomic profiling" approach. Besides, we evaluated toxinological properties and compared the effects with the Bothrops asper snake venom activities. The RP-HPLC profile showed similarities with the L. acrochorda snake venom from the Northwestern ecoregion of Colombia. However, the results displayed differences in the protein families identified, probably due to the proteomic identification strategy. The in vitro and in vivo tests showed a L. acrochorda snake venom with Phospholipase A₂ and metalloproteinase activities related to myotoxic, edematic, and hemorrhagic effects. Nevertheless, the L. acrochorda snake venom displayed a low lethality despite a large amount of inoculated venom. This investigation's results will help us improve the knowledge about the relationship between the clinical manifestations of L. acrochorda envenomation and the venom protein content.

Action of Varespladib (LY-315920), a Phospholipase A2 Inhibitor, on the Enzymatic, Coagulant and Haemorrhagic Activities of Lachesis muta rhombeata (South-American Bushmaster) Venom

Varespladib (VPL) was primarily developed to treat inflammatory disturbances associated with high levels of serum phospholipase A₂ (PLA₂). VPL has also demonstrated to be a potential antivenom support agent to prevent PLA₂-dependent effects produced by snake venoms. In this study, we examined the action of VPL on the coagulant, haemorrhagic and enzymatic activities of Lachesis muta rhombeata (South-American bushmaster) venom. Conventional colorimetric enzymatic assays were performed for PLA₂, caseinolytic and esterasic activities; in vitro coagulant activities for prothrombin time (PT) and activated partial thromboplastin time (aPTT) were performed in rat citrated plasma through a quick timer coagulometer, whereas the dimensions of haemorrhagic haloes obtained after i.d. injections of venom in Wistar rats were determined using ImageJ software. Venom (1 mg/ml) exhibited accentuated enzymatic activities for proteases and PLA₂in vitro, with VPL abolishing the PLA₂ activity from 0.01 mM; VPL did not affect caseinolytic and esterasic activities at any tested concentrations (0.001–1 mM). In rat citrated plasma in vitro, VPL (1 mM) alone efficiently prevented the venom (1 mg/ml)-induced procoagulant disorder associated to extrinsic (PT) pathway, whereas its association with a commercial antivenom successfully prevented changes in both intrinsic (aPTT) and extrinsic (PT) pathways; commercial antivenom by itself failed to avoid the procoagulant disorders by this venom. Venom (0.5 mg/kg)-induced hemorrhagic activity was slightly reduced by VPL (1 mM) alone or combined with antivenom (antivenom:venom ratio 1:3 ‘v/w’) in rats, with antivenom alone producing no protective action on this parameter. In conclusion, VPL does not inhibit other major enzymatic groups of L. m. rhombeata venom, with its high PLA₂ antagonize activity efficaciously preventing the venom-induced coagulation disturbances.

Protective action of N-acetyl-L-cysteine associated with a polyvalent antivenom on the envenomation induced by Lachesis muta muta (South American bushmaster) in rats

In this study, we examined the potential use of N-acetyl-L-cysteine (NAC) in association with a polyvalent antivenom and as stand-alone therapy to reduce the acute local and systemic effects induced by Lachesis muta muta venom in rats. Male Wistar rats (300-350 g) were exposed to L. m. muta venom (1.5 mg/kg - i.m.) and subsequently treated with anti-Bothrops/Lachesis serum (antivenom:venom ratio 1:3 'v/w' - i.p.) and NAC (150 mg/kg - i.p.) separately or in association; the animals were monitored for 120 min to assess changes in temperature, locomotor activity, local oedema formation and the prevalence of haemorrhaging. After this time, animals were anesthetized in order to collect blood samples through intracardiac puncture and then euthanized for collecting tissue samples; the hematological-biochemical and histopathological analyses were performed through conventional methods. L. m. muta venom produced pronounced local oedema, subcutaneous haemorrhage and myonecrosis, with both antivenom and NAC successfully reducing the extent of the myonecrotic lesion when individually administered; their association also prevented the occurrence of subcutaneous haemorrhage. Venom-induced creatine kinase (CK) release was significantly prevented by NAC alone or in combination with antivenom; NAC alone failed to reduce the release of hepatotoxic (alanine aminotransferase) and nephrotoxic (creatinine) serum biomarkers induced by L. m. muta venom. Venom induced significant increase of leucocytes which was also associated with an increase of neutrophils, eosinophils and monocytes; antivenom and NAC partially reduced these alterations, with NAC alone significantly preventing the increase of eosinophils whereas neither NAC or antivenom prevented the increase in monocytes. Venom did not induce changes in the erythrogram parameters. In the absence of a suitable antivenom, NAC has the potential to reduce a number of local and systemic effects caused by L. m. muta venom.

A brief review on the natural history, venomics and the medical importance of bushmaster (Lachesis) pit viper snakes

Snakes of the genus Lachesis, commonly known as bushmasters, are the largest venomous snakes in the Americas. Because these snakes have their habitats in areas of remote forests they are difficult to find, and consequently there are few studies of Lachesis taxa in their natural ecosystems. Bushmasters are distributed in tropical forest areas of South and Central America. In Brazil they can be found in the Amazon Rainforest and the Atlantic Forest. Despite the low incidence of cases, laquetic envenoming causes severe permanent sequelae due to the high amount of inoculated venom. These accidents are characterized by local pain, hemorrhage and myonecrosis that can be confused with bothropic envenomings. However, victims of Lachesis bites develop symptoms characteristic of Lachesis envenoming, known as vagal syndrome. An important message of this bibliographic synthesis exercise is that, despite having the proteomic profiles of all the taxa of the genus available, very few structure-function correlation studies have been carried out. Therefore the motivation for this review was to fill a gap in the literature on the genus Lachesis, about which there is no recent review. Here we discuss data scattered in a number of original articles published in specialized journals, spanning the evolutionary history and extant phylogeographic distribution of the bushmasters, their venom composition and diet, as well as the pathophysiology of their bites to humans and the biological activities and possible biotechnological applicability of their venom toxins.

Acidic Phospholipase A2-Peptide Derivative Modulates Oxidative Status and Microstructural Reorganization of Scar Tissue after Cutaneous Injury

From in vitro and in vivo models, the proliferative and healing potential of an acidic phospholipase A2 (LAPLA2) from Lachesis muta venom was investigated. The LAPLA2 proliferative activity was evaluated on fibroblasts and keratinocytes cultured, and the antioxidant and regenerative potential of LAPLA2 was analyzed in a murine model. The animal study consisted of four groups: C (negative control): 0.9% NaCl; SS (positive control): 1% silver sulfadiazine; L1 group: 0.5% LAPLA2; and L2 group: 0.25% LAPLA2. Wounds were topically treated daily for 12 days, and scar tissue samples were collected every 4 days. In vitro, LAPLA2 stimulated marked time-dependent cell proliferation. In vivo, it increased the antioxidant activity of superoxide dismutase (SOD) and catalase (CAT) and decreased malondialdehyde (MDA) and carbonyl protein (CP) levels in scar tissue treated with LAPLA2 at 0.5%. This peptide was effective in stimulating cellular proliferation, neoangiogenesis, type I and III collagen deposition, and maturation in a time-dependent-way, reducing the time required for wound closure. Our results indicated that LAPLA2 presented a remarkable potential in improving the oxidative status and microstructural reorganization of the scar tissue by stimulation of cellularity, angiogenesis, colagenogenesis, and wound contraction, suggesting that the peptide could be a potential candidate for a new healing drug.

Comparative characterization of Viperidae snake venoms from Perú reveals two compositional patterns of phospholipase A2 expression

Snake species within the Bothrops complex (sensu lato) are of medical relevance in Latin America, but knowledge on their venom characteristics is limited, or even unavailable, for some taxa. Perú harbors 17 species of pit vipers, within the genera Bothrops, Bothriechis, Bothrocophias, Porthidium, Crotalus, and Lachesis. This study compared the venoms of twelve species, through chromatographic and electrophoretic profiles, as well as proteolytic and phospholipase A₂ (PLA₂) activities. Also, proteomic profiles were analyzed for nine of the venoms using a shotgun approach. Results unveiled conspicuous differences in the expression of venom PLA₂s among species, six of them presenting scarce levels as judged by RP-HPLC profiles. Since most species within the bothropoid lineage possess venoms with high to intermediate abundances of this protein family, our findings suggest the existence of a phenotypic duality in the expression of venom PLA₂s within the Bothrops (sensu lato) complex. Bothrops barnetti and Bothrocophias andianus venoms, very scarce in PLA₂s, were shown to lack significant myotoxic activity, highlighting that the observed variability in PLA₂ expression bears toxicological correlations with effects attributed to these proteins. Finally, an attempt to identify phylogenetic relationships of bothropoid species from Perú presenting low- or high-PLA₂ venom phenotypes showed an interspersed pattern, thus precluding a simple phylogenetic interpretation of this venom compositional dichotomy.

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Venoms from 12 viperids of Perú were compared.

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Conspicuous differences in the expression of PLA₂ were found.

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Venoms presenting scarce levels of PLA₂ lack myotoxicity.

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A new phenotypic dichotomy in venom PLA₂ expression is described within Bothrops (sensu lato).

Development of a generic high-throughput screening assay for profiling snake venom protease activity after high-resolution chromatographic fractionation

Snakebites cause upwards of 1.8 million envenomings, 138,000 deaths and 500,000 cases of long term morbidity each year. Viper snake venoms (family Viperidae) generally contain a high proportion of proteases which can cause devastating effects such as hemorrhage, coagulopathy, edema, necrosis, and severe pain, in envenomed victims. In this study, analytical techniques were combined with enzymatic assays to develop a novel method for the detection of snake venom protease activity by using rhodamine-110-peptide substrate. In the so called at-line nanofractionation set up, crude venoms were first separated with reversed phase liquid chromatography, after which fractions were collected onto 384-well plates. Protease activity assays were then performed in the 384-well plates and bioassay chromatograms were constructed revealing protease activity. Parallel obtained UV absorbance, MS and proteomics data from a previous study facilitated toxin identification. The application of the rhodamine-110-peptide substrate assay showed significantly greater sensitivity compared to prior assays using casein-FITC as the substrate. Moreover, cross referencing UV and MS data and resulted in the detection of a number of tentative proteases suspected to exhibit protease activity, including snake venom serine proteases from Calloselasma rhodostoma and Daboia russelli venom and a snake venom metalloproteinase from the venom of Echis ocellatus. Our data demonstrate that his methodology can be a useful tool for selectively identifying snake venom proteases, and can be applied to provide a better understanding of protease-induced pathologies and the development of novel therapeutics for treating snakebite.

Mitochondriotropic action and DNA protection: Interactions between phenolic acids and enzymes

The protective action of caffeic (CA) and syringic (SA) acids on the genotoxicity exercised by snake venoms was investigated in this study. Molecular interactions between phenolic acids and the enzyme succinate dehydrogenase were also explored. In the electrophoresis assay, SA did not inhibit the genotoxicity induced by the venom. However, CA partially inhibited DNA degradation. In the comet assay, SA and CA exerted an inhibitory effect on the venom-induced fragmentation. Succinate dehydrogenase presented, in computational analyzes, favorable energies to the molecular bond to both the malonic acid and the phenolic compounds evaluated. In the enzymatic activity assays, SA inhibited succinate dehydrogenase and interfered in the interaction of malonic acid. Meanwhile, CA potentiated the inhibition exerted by the malonic acid. The results suggest transient interactions between toxins present in venoms and phenolic acids, mainly by hydrogen interactions, which corroborate with the data from previous works.

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

Background:

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 53^rd 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.

Structurally Robust and Functionally Highly Versatile-C-Type Lectin (-Related) Proteins in Snake Venoms

Snake venoms contain an astounding variety of different proteins. Among them are numerous C-type lectin family members, which are grouped into classical Ca²⁺- and sugar-binding lectins and the non-sugar-binding snake venom C-type lectin-related proteins (SV-CLRPs), also called snaclecs. Both groups share the robust C-type lectin domain (CTLD) fold but differ in a long loop, which either contributes to a sugar-binding site or is expanded into a loop-swapping heterodimerization domain between two CLRP subunits. Most C-type lectin (-related) proteins assemble in ordered supramolecular complexes with a high versatility of subunit numbers and geometric arrays. Similarly versatile is their ability to inhibit or block their target molecules as well as to agonistically stimulate or antagonistically blunt a cellular reaction triggered by their target receptor. By utilizing distinct interaction sites differentially, SV-CLRPs target a plethora of molecules, such as distinct coagulation factors and receptors of platelets and endothelial cells that are involved in hemostasis, thrombus formation, inflammation and hematogenous metastasis. Because of their robust structure and their high affinity towards their clinically relevant targets, SV-CLRPs are and will potentially be valuable prototypes to develop new diagnostic and therapeutic tools in medicine, provided that the molecular mechanisms underlying their versatility are disclosed.

The protective effect exerted by ascorbic acid on DNA fragmentation of human leukocytes induced by Lachesis muta muta venom

The objective of this study was to evaluate the genotoxic and mutagenic effects of the toxins present in Lachesis muta muta's venom on human peripheral blood leukocytes and the protective potential of ascorbic acid on DNA fragmentation. The venom of L. muta muta was incubated in different concentrations (1, 2.5, 5, 7.5, 10, 15, 20, 30, 40, 50, 60, and 120 µg/mL) with human blood to evaluate DNA fragmentation using the comet, agarose gel electrophoresis, and micronucleus assays. In these concentrations evaluated, the venom of L. muta muta induced genotoxicity (comet assay and agarose gel electrophoresis) and mutagenicity (micronucleus test), but they were not cytotoxic, as they did not change the rate of cell proliferation after cytokinesis blockade with cytochalasin B. The ascorbic acid significantly inhibited the genotoxicity induced by L. muta muta venom in the proportions evaluated (1:0.1 and 1:0.5, venom/ascorbic acid - w/w). Thus, future studies are needed to elucidate the protective mechanisms of ascorbic acid on the genotoxic effects induced by toxins present in snake venoms.

Anti-Ophidian Properties of Herbal Medicinal Plants: Could it be a Remedy for Snake Bite Envenomation?

Snake bite envenoming causes high rates of morbidity and mortality and is one of the serious health-related concerns all over the globe. Around 3200 species of snakes have been discovered till date. Amid these species, about 1300 species of snakes are venomous. On account of its severity, World Health Organization (WHO) recently included snakebite envenoming in the list of neglected tropical diseases. Immunotherapy has partially solved the issues related to snakebite envenomation. However, it is associated with numerous adverse effects, due to which alternative treatment strategies are required for the treatment of snakebite. Traditionally, a large repository of herbal medicinal plants is known to possess activity against snake venom. An exploration of the therapeutic benefits of these medicinal plants used for the treatment of snakebites reveals the presence of various potential phytochemicals. The aim of the present review is to provide an outline regarding poisonous snakes all over the world, various compositions of snake venom, adverse effects related to anti-snake venom and numerous medicinal plants used for the anti-ophidian activity.

In vitro assessment of cytotoxic activities of Lachesis muta muta snake venom

Envenomation by the bushmaster snake Lachesis muta muta is considered severe, characterized by local effects including necrosis, the main cause of permanent disability. However, cellular mechanisms related to cell death and tissue destruction, triggered by snake venoms, are poorly explored. The purpose of this study was to investigate the cytotoxic effect caused by L. m. muta venom in normal human keratinocytes and to identify the cellular processes involved in in cellulo envenomation. In order to investigate venom effect on different cell types, Alamar Blue assay was performed to quantify levels of cellular metabolism as a readout of cell viability. Apoptosis, necrosis and changes in mitochondrial membrane potential were evaluated by flow cytometry, while induction of autophagy was assessed by expression of GFP-LC3 and analyzed using fluorescence microscopy. The cytotoxic potential of the venom is shown by reduced cell viability in a concentration-dependent manner. It was also observed the sequential appearance of cells undergoing autophagy (by 6 hours), apoptosis and necrosis (12 and 24 hours). Morphologically, incubation with L. m. muta venom led to a significant cellular retraction and formation of cellular aggregates. These results indicate that L. m. muta venom is cytotoxic to normal human keratinocytes and other cell lines, and this toxicity involves the integration of distinct modes of cell death. Autophagy as a cell death mechanism, in addition to apoptosis and necrosis, can help to unravel cellular pathways and mechanisms triggered by the venom. Understanding the mechanisms that underlie cellular damage and tissue destruction will be useful in the development of alternative therapies against snakebites.

LmrBPP9: A synthetic bradykinin-potentiating peptide from Lachesis muta rhombeata venom that inhibits the angiotensin-converting enzyme activity in vitro and reduces the blood pressure of hypertensive rats

Bradykinin-potentiating peptides (BPPs) are an important group of toxins present in Lachesis muta rhombeata venom. They act directly at renin-angiotensin-aldosterone system, through the inhibition of angiotensin-converting enzyme (ACE). This action may contribute to the hypotensive shock observed during the envenoming by this species. Thus, the main goal of this study was the solid-phase synthesis of a BPP found in L. m. rhombeata venom and its in vitro and in vivo characterization in relation to ACE inhibition and hypotensive activity, respectively. The LmrBPP9 peptide was synthesized using an automated solid-phase peptide synthesizer and purified by reversed-phase fast protein liquid chromatography (FPLC). The in vitro IC50 of the synthetic peptide is 4.25 ± 0.10 μM, showing a great capacity of ACE inhibition. The in vivo studies showed that LmrBPP9 induces blood pressure reduction, both in normotensive and hypertensive rats, being more pronounced in the last ones. These results agree with the in vitro results, showing that the synthetic peptide LmrBPP9 is a potential molecule to the development of a new antihypertensive drug.

Characterization of the Venom of C. d. cumanesis of Colombia: Proteomic Analysis and Antivenomic Study

The Colombian rattlesnake Crotalus durissus cumanensis is distributed in three geographic zones of the country: the Atlantic Coast, the upper valley of the Magdalena River, and the eastern plains of the Colombian Orinoquía. Its venom induces neurological symptoms, such as eyelid ptosis, myasthenic facies, and paralysis of the respiratory muscles, which can lead to death. Identification and analysis of C. d. cumanensis showed nine groups of proteins responsible for the neurotoxic effect, of which the crotoxin complex was the most abundant (64.71%). Immunorecognition tests of C. d. cumanensis showed that the use of a commercial antivenom manufactured in Mexico resulted in immunoreactivity.

Computational Studies of Snake Venom Toxins

Most snake venom toxins are proteins, and participate to envenomation through a diverse array of bioactivities, such as bleeding, inflammation, and pain, cytotoxic, cardiotoxic or neurotoxic effects. The venom of a single snake species contains hundreds of toxins, and the venoms of the 725 species of venomous snakes represent a large pool of potentially bioactive proteins. Despite considerable discovery efforts, most of the snake venom toxins are still uncharacterized. Modern bioinformatics tools have been recently developed to mine snake venoms, helping focus experimental research on the most potentially interesting toxins. Some computational techniques predict toxin molecular targets, and the binding mode to these targets. This review gives an overview of current knowledge on the ~2200 sequences, and more than 400 three-dimensional structures of snake toxins deposited in public repositories, as well as of molecular modeling studies of the interaction between these toxins and their molecular targets. We also describe how modern bioinformatics have been used to study the snake venom protein phospholipase A2, the small basic myotoxin Crotamine, and the three-finger peptide Mambalgin.

Identification of B cell recognized linear epitopes in a snake venom serine proteinase from the central American bushmaster Lachesis stenophrys

Snake venom serine proteinases are toxins that perturb hemostasis acting on proteins from the blood coagulation cascade, the fibrinolytic or the kallikrein-kinin system. Despite the relevance of these enzymes in envenomations by viper bites, the characterization of the antibody response to these toxins at the molecular level has not been previously addressed. In this work surface-located B cell recognized linear epitopes from a Lachesis stenophrys venom serine proteinase (UniProt accession number Q072L7) were predicted using an artificial neuronal network at the ABCpred server, the corresponding peptides were synthesized and their immunoreactivity was analyzed against a panel of experimental and therapeutic antivenoms. A molecular model of the L. stenophrys enzyme was built using as a template the structure of the D. acutus Dav-PA serine proteinase (Q9I8X1), which displays the highest degree of sequence similarity to the L. stenophrys enzyme among proteins of known 3D structure, and the surface-located epitopes were identified in the protein model using iCn3D. A total of 13 peptides corresponding to the surface exposed predicted epitopes from L. stenophrys serine proteinase were synthesized and, their reactivity with a rabbit antiserum against the recombinant enzyme and a panel of antivenoms was evaluated by a capture ELISA. Some of the epitopes recognized by monospecific and polyspecific antivenoms comprise sequences overlapping motifs conserved in viper venom serine proteinases. The identification and characterization of relevant epitopes recognized by B cells in snake venom toxins may provide valuable information for the preparation of immunogens that help in the production of improved therapeutic antivenoms.

A Review and Database of Snake Venom Proteomes

Advances in the last decade combining transcriptomics with established proteomics methods have made possible rapid identification and quantification of protein families in snake venoms. Although over 100 studies have been published, the value of this information is increased when it is collated, allowing rapid assimilation and evaluation of evolutionary trends, geographical variation, and possible medical implications. This review brings together all compositional studies of snake venom proteomes published in the last decade. Compositional studies were identified for 132 snake species: 42 from 360 (12%) Elapidae (elapids), 20 from 101 (20%) Viperinae (true vipers), 65 from 239 (27%) Crotalinae (pit vipers), and five species of non-front-fanged snakes. Approximately 90% of their total venom composition consisted of eight protein families for elapids, 11 protein families for viperines and ten protein families for crotalines. There were four dominant protein families: phospholipase A₂s (the most common across all front-fanged snakes), metalloproteases, serine proteases and three-finger toxins. There were six secondary protein families: cysteine-rich secretory proteins, l-amino acid oxidases, kunitz peptides, C-type lectins/snaclecs, disintegrins and natriuretic peptides. Elapid venoms contained mostly three-finger toxins and phospholipase A₂s and viper venoms metalloproteases, phospholipase A₂s and serine proteases. Although 63 protein families were identified, more than half were present in <5% of snake species studied and always in low abundance. The importance of these minor component proteins remains unknown.

Cross-reactivity and cross-immunomodulation between venoms of the snakes Bothrops asper, Crotalus simus and Lachesis stenophrys, and its effect in the production of polyspecific antivenom for Central America

A mixture of the venoms of Bothrops asper, Crotalus simus and Lachesis stenophrys is used as immunogen to produce the polyspecific Central American antivenom (PoliVal-ICP). In this work, we studied the ability of each of these venoms to modulate the antibody response induced by the other two venoms included in the immunization mixture. For that, equine monospecific, bispecific and polyspecific antivenoms were prepared and compared regarding their ability to neutralize the phospholipase A₂, coagulant and lethal activities of each venom, and their anti-venom antibodies concentration. Results indicate that there is low cross-reactivity and cross-neutralization between venoms of B. asper, C. simus and L. stenophrys, hence justifying the use of all of them as immunogens for the production of the Central American antivenom. It was also found that the venom of B. asper reduces the anti-crotalic response while the venom of C. simus does not affect the anti-bothropic response. On the other hand, the venoms of B. asper and C. simus increase the anti-lachesic response, and L. stenoprhys venom reduced both the anti-bothropic and anti-crotalic responses. On the basis of these results, the immunization strategy can be adjusted by preventing or taking advantage of cross-immunomodulation between venoms, in order to maximize the antibody response towards all venoms. Immune responses can be improved by injecting horses with several immunogen mixtures, composed by one or two of the three venoms, and administering them at different times during the immunization, eventually generating a high titer against the three venoms. Our results suggest that addressing the issue of immunomodulation by venoms might improve antivenom manufacture worldwide.

Cross-reactivity, antivenomics, and neutralization of toxic activities of Lachesis venoms by polyspecific and monospecific antivenoms

Background

Bothrops, Crotalus and Lachesis represent the most medically relevant genera of pitvipers in Central and South America. Similarity in venom phenotype and physiopathological profile of envenomings caused by the four nominal Lachesis species led us to hypothesize that an antivenom prepared against venom from any of them may exhibit paraspecificity against all the other congeneric taxa.

Methods

To assess this hypothesis, in this work we have applied antivenomics and immunochemical methods to investigate the immunoreactivity of three monovalent antivenoms and two polyvalent antivenoms towards the venoms from different geographic populations of three different Lachesis species. The ability of the antivenoms to neutralize the proteolytic, hemorrhagic, coagulant, and lethal activities of the seven Lachesis venoms was also investigated.

Results

A conspicuous pattern of immunorecognition and cross-neutralization for all effects was evident by the polyspecific antivenoms, indicating large immunoreactive epitope conservation across the genus during more than 10 million years since the Central and South American bushmasters diverged.

Conclusions

Despite the broad geographic distribution of Lachesis, antivenoms against venoms of different species are effective in the neutralization of congeneric venoms not used in the immunization mixture, indicating that they can be used equivalently for the clinical treatment of any lachesic envenoming.

General significance

This study demonstrates that antivenoms raised against venom of different Lachesis species are indistinctly effective in the neutralization of congeneric venoms not used in the immunization mixture, indicating that antivenoms against conspecific venoms may be used equivalently for the clinical treatment of envenomings caused by any bushmaster species.

Snakebite envenoming is a neglected public health problem in many developing countries and antivenom administration constitutes the mainstay in the treatment of such envenomings. Therapeutic antivenoms contain animal-derived antibodies against venom toxins and are produced by immunizing animals with the venom from one or several snake species from a defined geographical area. Defining the geographic boundaries of the efficiency of an antivenom therefore has implications for its rational and efficient use. In Central and South America most accidents are caused by pitvipers of the genus Bothrops, Crotalus and Lachesis. There are four Lachesis species distributed in a variety of habitats ranging from the Caribbean coast of Central America to the Atlantic rainforest of Brazil. Lachesis species cause severe envenomings in humans due to the toxicity of their venoms and also to the large amount of venom they inject into their victims. In this work we investigate the capability of several antivenoms to neutralize the toxic activities of a panel of Lachesis venoms. The results demonstrate that antivenoms raised by immunizing horses with the venoms of different Lachesis species are effective at neutralizing congeneric venoms not used in the immunization, indicating that they could be used equivalently for the clinical treatment of any lachesic envenoming.

Cross-recognition of a pit viper (Crotalinae) polyspecific antivenom explored through high-density peptide microarray epitope mapping

Snakebite antivenom is a 120 years old invention based on polyclonal mixtures of antibodies purified from the blood of hyper-immunized animals. Knowledge on antibody recognition sites (epitopes) on snake venom proteins is limited, but may be used to provide molecular level explanations for antivenom cross-reactivity. In turn, this may help guide antivenom development by elucidating immunological biases in existing antivenoms. In this study, we have identified and characterized linear elements of B-cell epitopes from 870 pit viper venom protein sequences by employing a high-throughput methodology based on custom designed high-density peptide microarrays. By combining data on antibody-peptide interactions with multiple sequence alignments of homologous toxin sequences and protein modelling, we have determined linear elements of antibody binding sites for snake venom metalloproteases (SVMPs), phospholipases A₂s (PLA₂s), and snake venom serine proteases (SVSPs). The studied antivenom antibodies were found to recognize linear elements in each of the three enzymatic toxin families. In contrast to a similar study of elapid (non-enzymatic) neurotoxins, these enzymatic toxins were generally not recognized at the catalytic active site responsible for toxicity, but instead at other sites, of which some are known for allosteric inhibition or for interaction with the tissue target. Antibody recognition was found to be preserved for several minor variations in the protein sequences, although the antibody-toxin interactions could often be eliminated completely by substitution of a single residue. This finding is likely to have large implications for the cross-reactivity of the antivenom and indicate that multiple different antibodies are likely to be needed for targeting an entire group of toxins in these recognized sites.

Although snakebite antivenom is a 120-year-old invention, saving lives and limbs of thousands of snakebite victims every year, little is known about the mechanisms and molecular interactions of how antivenoms neutralize snake toxins. Antivenoms are produced by immunizing large animals with cocktails of snake venoms resulting in antibodies recognizing toxic as well as non-toxic venom proteins to variable degrees. As a result, high doses of antivenom are needed for treating a snakebite victim, causing more severe adverse reactions due to a high burden of heterologous antivenom proteins. For the first time, we have characterized the antibody recognition sites on hundreds of pit viper toxins using high-throughput peptide microarray technology and an antivenom specific for three pit vipers inflicting a high number of bites in Central America. Most pit viper toxins are enzymes known to have a catalytic site important for toxicity. However, our results suggest that the employed antivenom generally does not target such sites, but instead inhibits toxicity by binding to alternative sites, possibly causing conformational shifts in the toxin structures or interference with toxin-target recognition. The identification of these toxin-specific recognition sites may explain why the antivenom is effective against certain snakebites from pit vipers whose venoms are not part of the immunization mixture.

Functional characterizations of venom phenotypes in the eastern diamondback rattlesnake (Crotalus adamanteus) and evidence for expression-driven divergence in toxic activities among populations

Phenotypes frequently vary across and within species. The connection between specific phenotypic effects and function, however, is less understood despite being essential to our understanding of the adaptive process. Snake venoms are ideal for identifying functionally important phenotypic variation because venom variation is common, and venoms can be functionally characterized through simple assays and toxicity measurements. Previous work with the eastern diamondback rattlesnake (Crotalus adamanteus) used multivariate statistical approaches to identify six unique venom phenotypes. We functionally characterized hemolytic, gelatinase, fibrinogenolytic, and coagulant activity for all six phenotypes, as well as one additional venom, to determine if the statistically significant differences in toxin expression levels previously documented corresponded to differences in venom activity. In general, statistical differences in toxin expression predicted the identified functional differences, or lack thereof, in toxic activity, demonstrating that the statistical approach used to characterize C. adamanteus venoms was a fair representation of biologically meaningful differences. Minor differences in activity not accounted for by the statistical model may be the result of amino-acid differences and/or post-translational modifications, but overall we were able to link variation in protein expression levels to variation in function as predicted by multivariate statistical approaches.

Experimental Lachesis muta rhombeata envenomation and effects of soursop (Annona muricata) as natural antivenom

Background

In the Atlantic forest of the North and Northeast regions of Brazil, local population often uses the fruit juice and the aqueous extract of leaves of soursop (Annona muricata L.) to treat Lachesis muta rhombeata envenomation. Envenomation is a relevant health issue in these areas, especially due to its severity and because the production and distribution of antivenom is limited in these regions. The aim of the present study was to evaluate the relevance of the use of soursop leaf extract and its juice against envenomation by Lachesis muta rhombeata.

Methods

We evaluated the biochemical, hematological and hemostatic parameters, the blood pressure, the inflammation process and the lethality induced by Lachesis muta rhombeata snake venom. We also assessed the action of the aqueous extract of leaves (AmL) and juice (AmJ) from A. muricata on the animal organism injected with L. m. rhombeata venom (LmrV) in the laboratory environment.

Results

LmrV induced a decrease of total protein, albumin and glucose; and increase of creatine kinase, aspartate aminotransferase, and urea concentrations. It provoked hemoconcentration followed by reduction of hematocrit, an increase in prothrombin time and partial thromboplastin time and a decrease of the blood pressure. LmrV induced the release of interleukin-6, an increase in neutrophils and changes in the serum protein profile, characteristic of the acute inflammatory process. LD₅₀ values were similar for the groups injected with LmrV and treated or untreated with AmJ and AmL. Both treatments play a role on the maintenance of blood glucose, urea and coagulation parameters and exert a protective action against the myotoxicity. However, they seem to worsen the hypotension caused by LmrV.

Conclusion

The treatments with AmJ and AmL present some beneficial actions, but they might intensify some effects of the venom. Therefore, additional studies on A. muricata are necessary to enable its use as natural antivenom for bushmaster snakebite.

Proteomic characterization and comparison of venoms from two elapid snakes (Bungarus multicinctus and Naja atra) from China

Bungarus multicinctus (many-banded krait) and Naja atra (Chinese cobra) are widely distributed and medically important venomous snakes in China; however, their venom proteomic profiles have not been fully compared. Here, we fractionated crude venoms and analyzed them using a combination of proteomic techniques. Three-finger toxins (3-FTx) and phospholipase A2 (PLA2) were most abundant in both species, respectively accounting for 32.6% and 66.4% of total B. multicinctus venom, and 84.3% and 12.2% of total N. atra venom. Venoms from these two species contained one common protein family and six less abundant species-specific protein families. The proteomic profiles of B. multicinctus and N. atra venoms and analysis of toxicological activity in mice suggested that 3-FTx and PLA2 are the major contributors to clinical symptoms caused by envenomation. The venoms differed in enzymatic activity, likely the result of inter-specific variation in the amount of related venom components. Antivenomics assessment revealed that a small number of venom components (3-FTxs and PLA2s in B. multicinctus, and 3-FTxs in N. atra) could not be immunocaptured completely, suggesting that we should pay attention to enhancing the immune response of these components in designing commercial antivenoms for B. multicinctus and N. atra.

BIOLOGICAL SIGNIFICANCE

The proteomic profiles of venoms from two medically important snake species - B. multicinctus and N. atra - have been explored. Quantitative and qualitative differences are evident in both venoms when proteomic profiles and transcriptomic results are compared; this is a reminder that combined approaches are needed to explore the precise composition of snake venom. Two protein families (3-FTx and PLA2) of high abundance in these snake venoms are major players in the biochemical and pharmacological effects of envenomation. Elucidation of the proteomic profiles of these snake venoms is helpful in understanding composition-function relationships and will facilitate the clinical application of antivenoms.

Identification of hyaluronidase and phospholipase B in Lachesis muta rhombeata venom

Hyaluronidases contribute to local and systemic damages after envenoming, since they act as spreading factors cleaving the hyaluronan presents in the connective tissues of the victim, facilitating the diffusion of venom components. Although hyaluronidases are ubiquitous in snake venoms, they still have not been detected in transcriptomic analysis of the Lachesis venom gland and neither in the proteome of its venom performed previously. This work purified a hyaluronidase from Lachesis muta rhombeata venom whose molecular mass was estimated by SDS-PAGE to be 60 kDa. The hyaluronidase was more active at pH 6 and 37 °C when salt concentration was kept constant and more active in the presence of 0.15 M monovalent ions when the pH was kept at 6. Venom was fractionated by reversed-phase liquid chromatography (RPLC). Edman sequencing after RPLC failed to detect hyaluronidase, but identified a new serine proteinase isoform. The hyaluronidase was identified by mass spectrometry analysis of the protein bands in SDS-PAGE. Additionally, phospholipase B was identified for the first time in Lachesis genus venom. The discovery of new bioactive molecules might contribute to the design of novel drugs and biotechnology products as well as to development of more effective treatments against the envenoming.

Post-transcriptional Mechanisms Contribute Little to Phenotypic Variation in Snake Venoms

Protein expression is a major link in the genotype–phenotype relationship, and processes affecting protein abundances, such as rates of transcription and translation, could contribute to phenotypic evolution if they generate heritable variation. Recent work has suggested that mRNA abundances do not accurately predict final protein abundances, which would imply that post-transcriptional regulatory processes contribute significantly to phenotypes. Post-transcriptional processes also appear to buffer changes in transcriptional patterns as species diverge, suggesting that the transcriptional changes have little or no effect on the phenotypes undergoing study. We tested for concordance between mRNA and protein expression levels in snake venoms by means of mRNA-seq and quantitative mass spectrometry for 11 snakes representing 10 species, six genera, and three families. In contrast to most previous work, we found high correlations between venom gland transcriptomes and venom proteomes for 10 of our 11 comparisons. We tested for protein-level buffering of transcriptional changes during species divergence by comparing the difference between transcript abundance and protein abundance for three pairs of species and one intraspecific pair. We found no evidence for buffering during divergence of our three species pairs but did find evidence for protein-level buffering for our single intraspecific comparison, suggesting that buffering, if present, was a transient phenomenon in venom divergence. Our results demonstrated that post-transcriptional mechanisms did not contribute significantly to phenotypic evolution in venoms and suggest a more prominent and direct role for cis-regulatory evolution in phenotypic variation, particularly for snake venoms.

Sulfated Galactan from Palisada flagellifera Inhibits Toxic Effects of Lachesis muta Snake Venom

In Brazil, snakebites are a public health problem and accidents caused by Lachesis muta have the highest mortality index. Envenomation by L. muta is characterized by systemic (hypotension, bleeding and renal failure) and local effects (necrosis, pain and edema). The treatment to reverse the evolution of all the toxic effects is performed by injection of antivenom. However, such therapy does not effectively neutralize tissue damage or any other local effect, since in most cases victims delay seeking appropriate medical care. In this way, alternative therapies are in demand, and molecules from natural sources have been exhaustively tested. In this paper, we analyzed the inhibitory effect of a sulfated galactan obtained from the red seaweed Palisada flagellifera against some toxic activities of L. muta venom. Incubation of sulfated galactan with venom resulted in inhibition of hemolysis, coagulation, proteolysis, edema and hemorrhage. Neutralization of hemorrhage was also observed when the galactan was administered after or before the venom injection; thus mimicking a real in vivo situation. Moreover, the galactan blocked the edema caused by a phospholipase A₂ isolated from the same venom. Therefore, the galactan from P. flagellifera may represent a promising tool to treat envenomation by L. muta as a coadjuvant for the conventional antivenom.

Statistical analysis of the individual variability of 1D protein profiles as a tool in ecology: an application to parasitoid venom

Understanding the forces that shape eco-evolutionary patterns often requires linking phenotypes to genotypes, allowing characterization of these patterns at the molecular level. DNA-based markers are less informative in this aim compared to markers associated with gene expression and, more specifically, with protein quantities. The characterization of eco-evolutionary patterns also usually requires the analysis of large sample sizes to accurately estimate interindividual variability. However, the methods used to characterize and compare protein samples are generally expensive and time-consuming, which constrains the size of the produced data sets to few individuals. We present here a method that estimates the interindividual variability of protein quantities based on a global, semi-automatic analysis of 1D electrophoretic profiles, opening the way to rapid analysis and comparison of hundreds of individuals. The main original features of the method are the in silico normalization of sample protein quantities using pictures of electrophoresis gels at different staining levels, as well as a new method of analysis of electrophoretic profiles based on a median profile. We demonstrate that this method can accurately discriminate between species and between geographically distant or close populations, based on interindividual variation in venom protein profiles from three endoparasitoid wasps of two different genera (Psyttalia concolor, Psyttalia lounsburyi and Leptopilina boulardi). Finally, we discuss the experimental designs that would benefit from the use of this method.

Fossilized venom: the unusually conserved venom profiles of Heloderma species (beaded lizards and gila monsters)

Research into snake venoms has revealed extensive variation at all taxonomic levels. Lizard venoms, however, have received scant research attention in general, and no studies of intraclade variation in lizard venom composition have been attempted to date. Despite their iconic status and proven usefulness in drug design and discovery, highly venomous helodermatid lizards (gila monsters and beaded lizards) have remained neglected by toxinological research. Proteomic comparisons of venoms of three helodermatid lizards in this study has unravelled an unusual similarity in venom-composition, despite the long evolutionary time (~30 million years) separating H. suspectum from the other two species included in this study (H. exasperatum and H. horridum). Moreover, several genes encoding the major helodermatid toxins appeared to be extremely well-conserved under the influence of negative selection (but with these results regarded as preliminary due to the scarcity of available sequences). While the feeding ecologies of all species of helodermatid lizard are broadly similar, there are significant morphological differences between species, which impact upon relative niche occupation.

Testing the Toxicofera: comparative transcriptomics casts doubt on the single, early evolution of the reptile venom system

The identification of apparently conserved gene complements in the venom and salivary glands of a diverse set of reptiles led to the development of the Toxicofera hypothesis - the single, early evolution of the venom system in reptiles. However, this hypothesis is based largely on relatively small scale EST-based studies of only venom or salivary glands and toxic effects have been assigned to only some putative Toxicoferan toxins in some species. We set out to examine the distribution of these proposed venom toxin transcripts in order to investigate to what extent conservation of gene complements may reflect a bias in previous sampling efforts. Our quantitative transcriptomic analyses of venom and salivary glands and other body tissues in five species of reptile, together with the use of available RNA-Seq datasets for additional species, shows that the majority of genes used to support the establishment and expansion of the Toxicofera are in fact expressed in multiple body tissues and most likely represent general maintenance or "housekeeping" genes. The apparent conservation of gene complements across the Toxicofera therefore reflects an artefact of incomplete tissue sampling. We therefore conclude that venom has evolved multiple times in reptiles.

Preliminary assessment of Hedychium coronarium essential oil on fibrinogenolytic and coagulant activity induced by Bothrops and Lachesis snake venoms

BACKGROUND

The search for new inhibitors of snake venom toxins is essential to complement or even replace traditional antivenom therapy, especially in relation to compounds that neutralize the local effects of envenomations. Besides their possible use as alternative to traditional antivenom therapy, some plant species possess bioactive secondary metabolites including essential oils, which can be extracted from weeds that are considered substantial problems for agriculture, such as Hedychium coronarium.

METHODS

The essential oils of leaves and rhizomes from H. coronarium were extracted by hydrodistillation, and their potential inhibitory effects on the coagulant and fibrinogenolytic activities induced by the venoms of Lachesis muta, Bothrops atrox and Bothrops moojeni were analyzed. Citrated human plasma was used to evaluate the clotting time whereas changes in fibrinogen molecules were visualized by electrophoresis in polyacrylamide gel. The experimental design used for testing coagulation inhibition was randomized in a 3 × 2 factorial arrangement (concentration × essential oils), with three replications. The essential oils were compared since they were extracted from different organs of the same botanical species, H. coronarium.

RESULTS

The results suggest that the oils interact with venom proteases and plasma constituents, since all oils evaluated, when previously incubated with venoms, were able to inhibit the clotting effect, with less inhibition when oils and plasma were preincubated prior to the addition of venoms.

CONCLUSIONS

Thus, after extensive characterization of their pharmacological and toxicological effects, the essential oils can be used as an alternative to complement serum therapy, especially considering that these plant metabolites generally do not require specific formulations and may be used topically immediately after extraction.