From birth to bite: the evolutionary ecology of India's medically most important snake venoms.

BACKGROUND: Snake venoms can exhibit remarkable inter- and intraspecific variation. While diverse ecological and environmental factors are theorised to explain this variation, only a handful of studies have attempted to unravel their precise roles. This knowledge gap not only impedes our understanding of venom evolution but may also have dire consequences on snakebite treatment. To address this shortcoming, we investigated the evolutionary ecology of venoms of Russell's viper (Daboia russelii) and spectacled cobra (Naja naja), India's two clinically most important snakes responsible for an alarming number of human deaths and disabilities. METHODOLOGY: Several individuals (n = 226) of D. russelii and N. naja belonging to multiple clutches (n = 9) and their mothers were maintained in captivity to source ontogenetic stage-specific venoms. Using various in vitro and in vivo assays, we assessed the significance of prey, ontogeny and sex in driving venom composition, function, and potency. RESULTS: Considerable ontogenetic shifts in venom profiles were observed in D. russelii, with the venoms of newborns being many times as potent as juveniles and adults against mammalian (2.3-2.5 ×) and reptilian (2-10 ×) prey. This is the first documentation of the ontogenetic shift in viperine snakes. In stark contrast, N. naja, which shares a biogeographic distribution similar to D. russelii, deployed identical biochemical cocktails across development. Furthermore, the binding kinetics of cobra venom toxins against synthetic target receptors from various prey and predators shed light on the evolutionary arms race. CONCLUSIONS: Our findings, therefore, provide fascinating insights into the roles of ecology and life history traits in shaping snake venoms.

Venomics and Peptidomics of Palearctic Vipers: A Clade-Wide Analysis of Seven Taxa of the Genera Vipera, Montivipera, Macrovipera, and Daboia across Türkiye.

Snake venom variations are a crucial factor to understand the consequences of snakebite envenoming worldwide, and therefore it is important to know about toxin composition alterations between taxa. Palearctic vipers of the genera Vipera, Montivipera, Macrovipera, and Daboia have high medical impacts across the Old World. One hotspot for their occurrence and diversity is Türkiye, located on the border between continents, but many of their venoms remain still understudied. Here, we present the venom compositions of seven Turkish viper taxa. By complementary mass spectrometry-based bottom-up and top-down workflows, the venom profiles were investigated on proteomics and peptidomics level. This study includes the first venom descriptions of Vipera berus barani, Vipera darevskii, Montivipera bulgardaghica albizona, and Montivipera xanthina, as well as the first snake venomics profiles of Turkish Macrovipera lebetinus obtusa, and Daboia palaestinae, including an in-depth reanalysis of M. bulgardaghica bulgardaghica venom. Additionally, we identified the modular consensus sequence pEXW(PZ)1-2P(EI)/(KV)PPLE for bradykinin-potentiating peptides in viper venoms. For better insights into variations and potential impacts of medical significance, the venoms were compared against other Palearctic viper proteomes, including the first genus-wide Montivipera venom comparison. This will help the risk assessment of snakebite envenoming by these vipers and aid in predicting the venoms' pathophysiology and clinical treatments.

Unraveling the Reaction Mechanism of Russell's Viper Venom Factor X Activator: A Paradigm for the Reactivity of Zinc Metalloproteinases?

Snake venom metalloproteinases (SVMPs) are important drug targets against snakebite envenoming, the neglected tropical disease with the highest mortality worldwide. Here, we focus on Russell's viper (Daboia russelii), one of the "big four" snakes of the Indian subcontinent that, together, are responsible for ca. 50,000 fatalities annually. The "Russell's viper venom factor X activator" (RVV-X), a highly toxic metalloproteinase, activates the blood coagulation factor X (FX), leading to the prey's abnormal blood clotting and death. Given its tremendous public health impact, the WHO recognized an urgent need to develop efficient, heat-stable, and affordable-for-all small-molecule inhibitors, for which a deep understanding of the mechanisms of action of snake's principal toxins is fundamental. In this study, we determine the catalytic mechanism of RVV-X by using a density functional theory/molecular mechanics (DFT:MM) methodology to calculate its free energy profile. The results showed that the catalytic process takes place via two steps. The first step involves a nucleophilic attack by an in situ generated hydroxide ion on the substrate carbonyl, yielding an activation barrier of 17.7 kcal·mol-1, while the second step corresponds to protonation of the peptide nitrogen and peptide bond cleavage with an energy barrier of 23.1 kcal·mol-1. Our study shows a unique role played by Zn2+ in catalysis by lowering the pKa of the Zn2+-bound water molecule, enough to permit the swift formation of the hydroxide nucleophile through barrierless deprotonation by the formally much less basic Glu140. Without the Zn2+ cofactor, this step would be rate-limiting.

Functional Characterization and Anti-Tumor Effect of a Novel Group II Secreted Phospholipase A2 from Snake Venom of Saudi Cerastes cerates gasperetti.

Secreted phospholipases A2 are snake-venom proteins with many biological activities, notably anti-tumor activity. Phospholipases from the same snake type but different geographical locations have shown similar biochemical and biological activities with minor differences in protein sequences. Thus, the discovery of a new phospholipase A2 with unique characteristics identified in a previously studied venom could suggest the origins of these differences. Here, a new Group II secreted phospholipase A2 (Cc-PLA2-II) from the snake venom of Saudi Cerastes cerastes gasperetti was isolated and characterized. The purified enzyme had a molecular weight of 13.945 kDa and showed high specific activity on emulsified phosphatidylcholine of 1560 U/mg at pH 9.5 and 50 °C with strict calcium dependence. Interestingly, stability in extreme pH and high temperatures was observed after enzyme incubation at several pH levels and temperatures. Moreover, a significant dose-dependent cytotoxic anti-tumor effect against six human cancer cell lines was observed with concentrations of Cc-PLA2 ranging from 2.5 to 8 µM. No cytotoxic effect on normal human umbilical-vein endothelial cells was noted. These results suggest that Cc-PLA2-II potentially has angiogenic activity of besides cytotoxicity as part of its anti-tumor mechanism. This study justifies the inclusion of this enzyme in many applications for anticancer drug development.

Viper venoms drive the macrophages and hepatocytes to sequester and clear platelets: novel mechanism and therapeutic strategy for venom-induced thrombocytopenia.

Venomous snakebites cause clinical manifestations that range from local to systemic and are considered a significant global health challenge. Persistent or refractory thrombocytopenia has been frequently reported in snakebite patients, especially in cases caused by viperidae snakes. Viper envenomation-induced thrombocytopenia may persist in the absence of significant consumption coagulopathy even after the antivenom treatment, yet the mechanism remains largely unknown. Our study aims to investigate the mechanism and discover novel therapeutic targets for coagulopathy-independent thrombocytopenia caused by viper envenomation. Here we found that patients bitten by Protobothrops mucrosquamatus and Trimeresurus stejnegeri, rather than Naja. atra may develop antivenom-resistant and coagulopathy-independent thrombocytopenia. Crude venoms and the derived C-type lectin-like proteins from these vipers significantly increased platelet surface expression of neuraminidase and platelet desialylation, therefore led to platelet ingestion by both macrophages and hepatocytes in vitro, and drastically decreased peripheral platelet counts in vivo. Our study is the first to demonstrate that desialylation-mediated platelet clearance is a novel mechanism of viper envenomation-induced refractory thrombocytopenia and C-type lectin-like proteins derived from the viper venoms contribute to snake venom-induced thrombocytopenia. The results of this study suggest the inhibition of platelet desialylation as a novel therapeutic strategy against viper venom-induced refractory thrombocytopenia.

A Genus-Wide Bioactivity Analysis of Daboia (Viperinae: Viperidae) Viper Venoms Reveals Widespread Variation in Haemotoxic Properties.

The snake genus Daboia (Viperidae: Viperinae; Oppel, 1811) contains five species: D. deserti, D. mauritanica, and D. palaestinae, found in Afro-Arabia, and the Russell's vipers D. russelii and D. siamensis, found in Asia. Russell's vipers are responsible for a major proportion of the medically important snakebites that occur in the regions they inhabit, and their venoms are notorious for their coagulopathic effects. While widely documented, the extent of venom variation within the Russell's vipers is poorly characterised, as is the venom activity of other species within the genus. In this study we investigated variation in the haemotoxic activity of Daboia using twelve venoms from all five species, including multiple variants of D. russelii, D. siamensis, and D. palaestinae. We tested the venoms on human plasma using thromboelastography, dose-response coagulometry analyses, and calibrated automated thrombography, and on human fibrinogen by thromboelastography and fibrinogen gels. We assessed activation of blood factors X and prothrombin by the venoms using fluorometry. Variation in venom activity was evident in all experiments. The Asian species D. russelii and D. siamensis and the African species D. mauritanica possessed procoagulant venom, while D. deserti and D. palaestinae were net-anticoagulant. Of the Russell's vipers, the venom of D. siamensis from Myanmar was most toxic and D. russelli of Sri Lanka the least. Activation of both factor X and prothrombin was evident by all venoms, though at differential levels. Fibrinogenolytic activity varied extensively throughout the genus and followed no phylogenetic trends. This venom variability underpins one of the many challenges facing treatment of Daboia snakebite envenoming. Comprehensive analyses of available antivenoms in neutralising these variable venom activities are therefore of utmost importance.

Evaluation of the Anticancer Potential of Crude, Irradiated Cerastes cerastes Snake Venom and Propolis Ethanolic Extract & Related Biological Alterations.

We aimed to evaluate the anticancer potential of crude venom (CV), γ irradiated Certastes cerastes venom (IRRV), and propolis ethanolic extract (PEE). IRRV showed a higher toxicity than CV, while CV-PEE showed higher toxicity than IRRV and CV against lung [A549] and prostate [PC3] cancer cells. Toxicity to [A549] and [PC3] cells was concentration and cell type dependent. In comparison to controls, apoptotic genes showed a significant upregulation of P53 and Casp-3 and a downregulation of Bcl-2. Also, induced elevated DNA accumulation in the [S] phase post PC3 cell treatment with IRRV and CV, as well as a significant DNA accumulation at G2/M phase after IRRV treatment of A549 cells. In contrast, PC3 cells showed a negligible cellular DNA accumulation after PEE treatment. Glutathione reductase [GR] was reduced in case of PC3 and A549 cell treated with IRRV, CV, and PEE compared with its values in untreated cell control. The Malondialdehyde [MDA] values in both cells recorded a significant elevation post IRRV treatment compared to the rest of the treatment regimen and untreated cell control. Similarly, IRRV and CV-PEE mix showed obviously higher reactive oxygen species [ROS] values than PC3 and A549 cell treatments with CV and PEE.

Crystal structure of human endothelin ETB receptor in complex with sarafotoxin S6b.

Sarafotoxins (SRTXs) are endothelin-like peptides extracted from snake venom. SRTXs stimulate the endothelin ETA and ETB receptors and enhance vasoconstriction, followed by left ventricular dysfunction and bronchoconstriction. SRTXs include four major isopeptides, S6a-d, with different subtype selectivities. Here, we report the crystal structure of the human ETB receptor in complex with the non-selective sarafotoxin S6b at 3.0 Å resolution. This structure reveals the similarities and differences between the binding modes of the endothelins and S6b. Moreover, molecular dynamics simulations based on the S6b-bound receptor provides structural insight into the subtype selectivity of the sarafotoxins. Our study clarifies the recognition mechanism of the endothelin-like peptide families.

Mass spectrometric analysis to unravel the venom proteome composition of Indian snakes: opening new avenues in clinical research.

INTRODUCTION: The 'Big Four' venomous snakes - Daboia russelii, Naja naja, Bungarus caeruleus, and Echis carinatus - are primarily responsible for the majority of snake envenomation in India. Several other lesser-known venomous snake species also inflict severe envenomation in the country. AREAS COVERED: A comprehensive analysis of the venom proteome composition of the 'Big Four' and other medically important venomous snakes of India and the effect of regional variation in venom composition on immunorecognition and/or neutralization by commercial antivenom was undertaken by searching the literature (from 1985 to date) available in large public databases. Further, mass spectrometric identification of poorly immunogenic toxins of snake venom (against which commercial polyvalent antivenom contains a significantly lower proportion of antibodies) and its impact on antivenom therapy against snakebite are discussed. The application of mass spectrometry to identify protein (toxin) complexes as well as drug prototypes from Indian snake venoms and the clinical importance of such studies are also highlighted. EXPERT OPINION: Further detailed clinical and proteomic research is warranted to better understand the effects of regional snake venom composition on the clinical manifestation of envenomation and antivenom therapy and to improve the production of antibodies against poorly immunogenic venom components.

Comprehensive Study of the Proteome and Transcriptome of the Venom of the Most Venomous European Viper: Discovery of a New Subclass of Ancestral Snake Venom Metalloproteinase Precursor-Derived Proteins.

The nose-horned viper, its nominotypical subspecies Vipera ammodytes ammodytes ( Vaa), in particular, is, medically, one of the most relevant snakes in Europe. The local and systemic clinical manifestations of poisoning by the venom of this snake are the result of the pathophysiological effects inflicted by enzymatic and nonenzymatic venom components acting, most prominently, on the blood, cardiovascular, and nerve systems. This venom is a very complex mixture of pharmacologically active proteins and peptides. To help improve the current antivenom therapy toward higher specificity and efficiency and to assist drug discovery, we have constructed, by combining transcriptomic and proteomic analyses, the most comprehensive library yet of the Vaa venom proteins and peptides. Sequence analysis of the venom gland cDNA library has revealed the presence of messages encoding 12 types of polypeptide precursors. The most abundant are those for metalloproteinase inhibitors (MPis), bradykinin-potentiating peptides (BPPs), and natriuretic peptides (NPs) (all three on a single precursor), snake C-type lectin-like proteins (snaclecs), serine proteases (SVSPs), P-II and P-III metalloproteinases (SVMPs), secreted phospholipases A2 (sPLA2s), and disintegrins (Dis). These constitute >88% of the venom transcriptome. At the protein level, 57 venom proteins belonging to 16 different protein families have been identified and, with SVSPs, sPLA2s, snaclecs, and SVMPs, comprise ∼80% of all venom proteins. Peptides detected in the venom include NPs, BPPs, and inhibitors of SVSPs and SVMPs. Of particular interest, a transcript coding for a protein similar to P-III SVMPs but lacking the MP domain was also found at the protein level in the venom. The existence of such proteins, also supported by finding similar venom gland transcripts in related snake species, has been demonstrated for the first time, justifying the proposal of a new P-IIIe subclass of ancestral SVMP precursor-derived proteins.

Dimeric Disintegrins from the Steppe Viper V. ursinii Venom.

Four dimeric disintegrins were isolated from the venom of the steppe viper V. ursinii using liquid chromatography. Disintegrins prevented adhesion of MCF7 cells to fibronectin, which indicates their interaction with integrin receptors of the αVß1 type. According to mass spectrometry data, the molar masses of disintegrins are about 14 kDa. The method of peptide mapping established the structure of a new heterodimeric disintegrin weighing 13 995.5 Da and shows that it belongs to the class of RGD/KGD-containing disintegrins.

Proteomic Analysis and Immuno-Profiling of Eastern India Russell's Viper ( Daboia russelii) Venom: Correlation between RVV Composition and Clinical Manifestations Post RV Bite.

The proteomes of Russell's viper venom (RVV) from Burdwan (RVV B) and Nadia (RVV N), the two districts of West Bengal, eastern India (EI), were investigated by gel-filtration chromatography (GFC) followed by tandem mass spectrometry of tryptic fragments of the fractions. A total of 73 and 69 proteins belonging to 15 snake venom protein families were identified in RVV B and RVV N, respectively, by MS/MS search against Viperidae (taxid 8689) protein entries of the nonredundant NCBI database. The minor differences in venom composition of both the EI RV were established unequivocally by their biochemical and pharmacological properties and by SDS-PAGE, gel filtration chromatography, and LC-MS/MS analyses. The composition of EI RVVs was well correlated with published reports on the pathophysiology of RV-envenomed patients from this part of the country. Venom-antivenom cross-reactivity determined by ELISA, Western blotting, and antivenomics approaches demonstrated poor recognition of low molecular mass (<20 kDa) RVV proteins by commercial polyvalent antivenoms, which was substantiated by neutralization of RVV enzymes by antivenom.

Proteomic analysis reveals geographic variation in venom composition of Russell's Viper in the Indian subcontinent: implications for clinical manifestations post-envenomation and antivenom treatment.

INTRODUCTION: The Russell's Viper (RV) (Daboia russelii), a category I medically important snake, is responsible for a significant level of morbidity and mortality in the Indian sub-continent. Areas covered: The current review highlights the variation in RV venom (RVV) composition from different geographical locales on the Indian sub-continent, as revealed by biochemical and proteomic analyses. A comparison of these RVV proteomes revealed significant differences in the number of toxin isoforms and relative toxin abundances, highlighting the impact of geographic location on RVV composition. Antivenom efficacy studies have shown differential neutralization of toxicity and enzymatic activity of different RVV samples from the Indian sub-continent by commercial polyvalent antivenom (PAV). The proteome analysis has provided deeper insights into the variation of RVV composition leading to differences in antivenom efficacy and severity of clinical manifestations post RV-envenomation across the Indian sub-continent. Expert commentary: Variation in RVV antigenicity due to geographical differences and poor recognition of low molecular mass (<20 kDa) RVV toxins by PAV are serious concerns for effective antivenom treatment against RV envenomation. Improvements in immunization protocols that take into account the poorly immunogenic components and geographic variation in RVV composition, can lead to better hospital management of RV bite patients.

Inhibition of Echis carinatus venom by DNA, a promising therapeutic molecule for snakebite management.

BACKGROUND: E. carinatus bite is a serious threat to South-Asian countries including India, as it causes the highest number of deaths and debilitating sustained tissue necrosis at the bite site. One of our previous studies has demonstrated the strong interaction between DNA and E. carinatus venom. Therefore, in this study, the effect of DNA on E. carinatus venom has been examined. METHODS: Here we show that calf thymus DNA interact strongly with E. carinatus venom and inhibits its enzymatic and pharmacological activities such as proteolytic, hemolytic, hyaluronidase, L-amino acid oxidase, NETosis, hemorrhage, pro-coagulant, and lethality. Further, using immunoblots and immunofluorescence, the study demonstrates the inhibition of proteolytic cleavage of several surface receptors on PMNs, PBMCs, and platelets by the DNA. CONCLUSIONS: This study for the first time explored the efficient inhibition of enzymatic, pharmacological and lethal properties of E. carinatus venom by the naked DNA and demonstrates the possible therapeutic application of it during snakebite management. GENERAL SIGNIFICANCE: This study identifies naked DNA as an effective defense weapon that has got the therapeutic potential to inhibit the detrimental effects of E. carinatus bite.

Macrovipecetin, a C-type lectin from Macrovipera lebetina venom, inhibits proliferation migration and invasion of SK-MEL-28 human melanoma cells and enhances their sensitivity to cisplatin.

BACKGROUND: The resistance of melanoma cells to cisplatin restricts its clinical use. Therefore, the search for novel tumor inhibitors and effective combination treatments that sensitize tumor cells to this drug are still needed. We purified macrovipecetin, a novel heterodimeric C-type lectin, from Macrovipera lebetina snake venom and investigated its anti-tumoral effect on its own or combined with cisplatin, in human melanoma cells. METHODS: Biochemical characterization, in vitro cells assays such as viability, apoptosis, adhesion, migration, invasion, Western blotting and in silico analysis were used in this study. RESULTS: Macrovipecetin decreased melanoma cell viability 100 times more than cisplatin. Interestingly, when combined with the drug, macrovipecetin enhanced the sensitivity of SK-MEL-28 cells by augmenting their apoptosis through increased expression of the apoptosis inducing factor (AIF) and activation of ERK1/2, p38, AKT and NF-κB. Moreover, macrovipecetin alone or combined with cisplatin induced the expression of TRADD, p53, Bax, Bim and Bad and down-regulated the Bcl-2 expression and ROS levels in SK-MEL-28 cells. Interestingly, these treatments impaired SK-MEL-28 cell adhesion, migration and invasion through modulating the function and expression of αvß3 integrin along with regulating E-cadherin, vimentin, ß-catenin, c-Src and RhoA expression. In silico study suggested that only the α chain of macrovipecetin interacts with a region overlapping the RGD motif binding site on this integrin. CONCLUSIONS: We validated the antitumor effect of macrovipecetin when combined, or not, with cisplatin on SK-MEL-28 cells. GENERAL SIGNIFICANCE: The presented work proposes the potential use of macrovipecetin and cisplatin in combination as an effective anti-melanoma treatment.

Liquid chromatographic nanofractionation with parallel mass spectrometric detection for the screening of plasmin inhibitors and (metallo)proteinases in snake venoms.

To better understand envenoming and to facilitate the development of new therapies for snakebite victims, rapid, sensitive, and robust methods for assessing the toxicity of individual venom proteins are required. Metalloproteinases comprise a major protein family responsible for many aspects of venom-induced haemotoxicity including coagulopathy, one of the most devastating effects of snake envenomation, and is characterized by fibrinogen depletion. Snake venoms are also known to contain anti-fibrinolytic agents with therapeutic potential, which makes them a good source of new plasmin inhibitors. The protease plasmin degrades fibrin clots, and changes in its activity can lead to life-threatening levels of fibrinolysis. Here, we present a methodology for the screening of plasmin inhibitors in snake venoms and the simultaneous assessment of general venom protease activity. Venom is first chromatographically separated followed by column effluent collection onto a 384-well plate using nanofractionation. Via a post-column split, mass spectrometry (MS) analysis of the effluent is performed in parallel. The nanofractionated venoms are exposed to a plasmin bioassay, and the resulting bioassay activity chromatograms are correlated to the MS data. To study observed proteolytic activity of venoms in more detail, venom fractions were exposed to variants of the plasmin bioassay in which the assay mixture was enriched with zinc or calcium ions, or the chelating agents EDTA or 1,10-phenanthroline were added. The plasmin activity screening system was applied to snake venoms and successfully detected compounds exhibiting antiplasmin (anti-fibrinolytic) activities in the venom of Daboia russelii, and metal-dependent proteases in the venom of Crotalus basiliscus. Graphical abstract ᅟ.

Isolation and characterization of an anti-leishmanial disintegrin from Cerastes cerastes venom.

Investigating new antimicrobial and antiparasitic components from Viperidae venoms represents an alternative therapeutic strategy. In this study, we report the characterization of a disintegrin isolated from Cerastes cerastes venom, exhibiting antiparasitic activity on Leishmania infantum promastigotes. Indeed, isolated disintegrin, referred to Disintegrin_Cc, induced 84.75% of parasiticidal activity and deep morphological alterations on the parasites. SDS-PAGE analysis indicated that this disintegrin was homogenous. This dimeric disintegrin of 14,193.97 Da contains an RGD domain and four intramolecular disulfide bridges. It presents a high percentage of identity with other related snake disintegrins. Predicted 3D structure indicated that this peptide shares partial homology with well-known active antimicrobial peptides. Disintegrin_Cc inhibited 80% of arachidonic acid-induced platelet aggregation. The obtained results suggest that the isolated molecule plays a dual role as a disintegrin and as an anti-leishmanial compound. This component could be useful as a drug in the treatment of leishmaniasis.

Toxin bioportides: exploring toxin biological activity and multifunctionality.

Toxins have been shown to have many biological functions and to constitute a rich source of drugs and biotechnological tools. We focus on toxins that not only have a specific activity, but also contain residues responsible for transmembrane penetration, which can be considered bioportides-a class of cell-penetrating peptides that are also intrinsically bioactive. Bioportides are potential tools in pharmacology and biotechnology as they help deliver substances and nanoparticles to intracellular targets. Bioportides characterized so far are peptides derived from human proteins, such as cytochrome c (CYCS), calcitonin receptor (camptide), and endothelial nitric oxide synthase (nosangiotide). However, toxins are usually disregarded as potential bioportides. In this review, we discuss the inclusion of some toxins and molecules derived thereof as a new class of bioportides based on structure activity relationship, minimization, and biological activity studies. The comparative analysis of the amino acid residue composition of toxin-derived bioportides and their short molecular variants is an innovative analytical strategy which allows us to understand natural toxin multifunctionality in vivo and plan novel pharmacological and biotechnological products. Furthermore, we discuss how many bioportide toxins have a rigid structure with amphiphilic properties important for both cell penetration and bioactivity.

Vipers of the Middle East: A Rich Source of Bioactive Molecules.

Snake venom serves as a tool of defense against threat and helps in prey digestion. It consists of a mixture of enzymes, such as phospholipase A2, metalloproteases, and l-amino acid oxidase, and toxins, including neurotoxins and cytotoxins. Beside their toxicity, venom components possess many pharmacological effects and have been used to design drugs and as biomarkers of diseases. Viperidae is one family of venomous snakes that is found nearly worldwide. However, three main vipers exist in the Middle Eastern region: Montivipera bornmuelleri, Macrovipera lebetina, and Vipera (Daboia) palaestinae. The venoms of these vipers have been the subject of many studies and are considered as a promising source of bioactive molecules. In this review, we present an overview of these three vipers, with a special focus on their venom composition as well as their biological activities, and we discuss further frameworks for the exploration of each venom.

Unraveling the Proteome Composition and Immuno-profiling of Western India Russell's Viper Venom for In-Depth Understanding of Its Pharmacological Properties, Clinical Manifestations, and Effective Antivenom Treatment.

The proteome composition of western India (WI) Russell's viper venom (RVV) was correlated with pharmacological properties and pathological manifestations of RV envenomation. Proteins in the 5-19 and 100-110 kDa mass ranges were the most predominate (∼35.1%) and least abundant (∼3.4%) components, respectively, of WI RVV. Non-reduced SDS-PAGE indicated the occurrence of multiple subunits, non-covalent oligomers, self-aggregation, and/or interactions among the RVV proteins. A total of 55 proteins belonging to 13 distinct snake venom families were unambiguously identified by ESI-LC-MS/MS analysis. Phospholipase A2 (32.5%) and Kunitz-type serine protease inhibitors (12.5%) represented the most abundant enzymatic and non-enzymatic proteins, respectively. However, ATPase, ADPase, and hyaluronidase, detected by enzyme assays, were not identified by proteomic analysis owing to limitations in protein database deposition. Several biochemical and pharmacological properties of WI RVV were also investigated. Neurological symptoms exhibited by some RV-bite patients in WI may be correlated to the presence of neurotoxic phospholipase A2 enzymes and Kunitz-type serine protease inhibitor complex in this venom. Monovalent antivenom was found to be better than polyvalent antivenom in immuno-recognition and neutralization of the tested pharmacological properties and enzyme activities of WI RVV; nevertheless, both antivenoms demonstrated poor cross-reactivity and neutralization of pharmacological activities shown by low-molecular-mass proteins (<18 kDa) of this venom.