ß-keto amyrin isolated from Cryptostegia grandiflora R. br. inhibits inflammation caused by Daboia russellii viper venom: Direct binding of ß-keto amyrin to phospholipase A2.

The search for mechanism-based anti-inflammatory therapies is of fundamental importance to avoid undesired off-target effects. Phospholipase A2 (PLA2) activity is a potential molecular target for anti-inflammatory drugs because it fuels arachidonic acid needed to synthesize inflammation mediators, such as prostaglandins. Herein, we aim to investigate the molecular mechanism by which ß-keto amyrin isolated from a methanolic extract of Cryptostegia grandiflora R. Br. Leaves can inhibit inflammation caused by Daboia russellii viper (DR) venom that mainly contains PLA2. We found that ß-keto amyrin neutralizes DR venom-induced paw-edema in a mouse model. Molecular docking of PLA2 with ß-keto amyrin complex resulted in a higher binding energy score of -8.86 kcal/mol and an inhibition constant of 611.7 nM. Diclofenac had a binding energy of -7.04 kcal/mol and an IC50 value of 620 nM, which predicts a poorer binding interaction than ß-keto amyrin. The higher conformational stability of ß-keto amyrin interaction compared to diclofenac is confirmed by molecular dynamics simulation. ß-keto amyrin isolated from C. grandiflora inhibits the PLA2 activity contained in Daboia russellii viper venom. The anti-inflammatory property of ß-keto amyrin is due to its direct binding into the active site of PLA2, thus inhibiting its enzyme activity.

In vitro immunoreactivity and in vivo neutralization of Trimeresurus gracilis venom with antivenoms targeting four pit viper species.

Snakebite envenomation is a significant global health issue that requires specific antivenom treatments. In Taiwan, available antivenoms target a variety of snakes, but none specifically target Trimeresurus gracilis, an endemic and protected species found in the high mountain areas of Taiwan. This study evaluated the effectiveness of existing antivenoms against T. gracilis venom, focusing on a bivalent antivenom developed for Trimeresurus stejnegeri and Protobothrops mucrosquamatus (TsPmAV), as well as monovalent antivenoms for Deinagkistrodon acutus (DaAV) and Gloydius brevicaudus (GbAV). Our research involved in vivo toxicity testing in mice and in vitro immunobinding experiments using (chaotropic) enzyme-linked immunosorbent assays, comparing venoms from four pit viper species (T. gracilis, T. stejnegeri, P. mucrosquamatus, and D. acutus) with three types of antivenoms. These findings indicate that TsPmAV partially neutralized T. gracilis venom, marginally surpassing the efficacy of DaAV. In vitro tests revealed that GbAV displayed higher binding capacities toward T. gracilis venom than TsPmAV or DaAV. Comparisons of electrophoretic profiles also reveal that T. gracilis venom has fewer snake venom C-type lectin like proteins than D. acutus, and has more P-I snake venom metalloproteases or fewer phospholipase A2 than G. brevicaudus, T. stejnegeri, or P. mucrosquamatus. This study highlights the need for antivenoms that specifically target T. gracilis, as current treatments using TsPmAV show limited effectiveness in neutralizing local effects in patients. These findings provide crucial insights into clinical treatment protocols and contribute to the understanding of the evolutionary adaptation of snake venom, aiding in the development of more effective antivenoms for human health.

Differential effects of the venoms of Russell's viper and Indian cobra on human myoblasts.

Local tissue damage following snakebite envenoming remains a poorly researched area. To develop better strategies to treat snakebites, it is critical to understand the mechanisms through which venom toxins induce envenomation effects including local tissue damage. Here, we demonstrate how the venoms of two medically important Indian snakes (Russell's viper and cobra) affect human skeletal muscle using a cultured human myoblast cell line. The data suggest that both venoms affect the viability of myoblasts. Russell's viper venom reduced the total number of cells, their migration, and the area of focal adhesions. It also suppressed myogenic differentiation and induced muscle atrophy. While cobra venom decreased the viability, it did not largely affect cell migration and focal adhesions. Cobra venom affected the formation of myotubes and induced atrophy. Cobra venom-induced atrophy could not be reversed by small molecule inhibitors such as varespladib (a phospholipase A2 inhibitor) and prinomastat (a metalloprotease inhibitor), and soluble activin type IIb receptor (a molecule used to promote regeneration of skeletal muscle), although the antivenom (raised against the Indian 'Big Four' snakes) has attenuated the effects. However, all these molecules rescued the myotubes from Russell's viper venom-induced atrophy. This study demonstrates key steps in the muscle regeneration process that are affected by both Indian Russell's viper and cobra venoms and offers insights into the potential causes of clinical features displayed in envenomed victims. Further research is required to investigate the molecular mechanisms of venom-induced myotoxicity under in vivo settings and develop better therapies for snakebite-induced muscle damage.

Daboialipase, a phospholipase A2 from Vipera russelli russelli venom posesses anti-platelet, anti-thrombin and anti-cancer properties.

Snake venoms are known to contain toxins capable of interfering with normal physiological processes of victims. Specificity of toxins from snake venoms give scope to identify new molecules with therapeutic action and/or help to understand different cellular mechanisms. Russell's viper venom (RVV) is a mixture of many bioactive molecules with enzymatic and non-enzymatic proteins. The present article describes Daboialipase (DLP), an enzymatic phospholipase A2 with molecular mass of 14.3 kDa isolated from RVV. DLP was obtained after cation exchange chromatography followed by size-exclusion high performance liquid chromatography (SE-HPLC). The isolated DLP presented strong inhibition of adenosine di-phosphate (ADP) and collagen induced platelet aggregation. It also showed anti-thrombin properties by significantly extending thrombin time in human blood samples. Trypan blue and resazurin cell viability assays confirmed time-dependent cytotoxic and cytostatic activities of DLP on MCF7 breast cancer cells, in vitro. DLP caused morphological changes and nuclear damage in MCF7 cells. However, DLP did not cause cytotoxic effects on non-cancer HaCaT cells. Peptide sequences of DLP obtained by O-HRLCMS analysis showed similarity with a previously reported PLA2 (Uniprot ID: PA2B_DABRR/PDB ID: 1VIP_A). An active Asp at 49th position, calcium ion binding site and anticoagulant activity sites were identified in 1 VIP_A. These findings are expected to contribute to designing new anti-platelet, anticoagulant and anti-cancer molecules.

Viper Venom Phospholipase A2 Database: The Structural and Functional Anatomy of a Primary Toxin in Envenomation.

Viper venom phospholipase A2 enzymes (vvPLA2s) and phospholipase A2-like (PLA2-like) proteins are two of the principal toxins in viper venom that are responsible for the severe myotoxic and neurotoxic effects caused by snakebite envenoming, among other pathologies. As snakebite envenoming is the deadliest neglected tropical disease, a complete understanding of these proteins' properties and their mechanisms of action is urgently needed. Therefore, we created a database comprising information on the holo-form, cofactor-bound 3D structure of 217 vvPLA2 and PLA2-like proteins in their physiologic environment, as well as 79 membrane-bound viper species from 24 genera, which we have made available to the scientific community to accelerate the development of new anti-snakebite drugs. In addition, the analysis of the sequenced, 3D structure of the database proteins reveals essential aspects of the anatomy of the proteins, their toxicity mechanisms, and the conserved binding site areas that may anchor universal interspecific inhibitors. Moreover, it pinpoints hypotheses for the molecular origin of the myotoxicity of the PLA2-like proteins. Altogether, this study provides an understanding of the diversity of these toxins and how they are conserved, and it indicates how to develop broad, interspecies, efficient small-molecule inhibitors to target the toxin's many mechanisms of action.

Proteome analysis of Daboia russelii venom, a medically important snake from the Indian sub-continent.

Daboia russelii is a category-I medically important snake throughout the Indian sub-continent contributing to majority of snakebite incidences in this part of the world. As such, extensive studies on its venom composition and search of efficient and appropriate interventions for its treatment become crucial. In this study, the proteome of Daboia russelii venom from Tanore, Rajshahi, Bangladesh was profiled using a combination of chromatographic and mass spectrometric techniques. A total of 37 different proteins belonging to 11 different snake venom protein families were detected. Proteomics analysis revealed the presence of major phospholipase A2 toxins. Daboiatoxin (both A and B subunits), the main lethal PLA2 toxin in the venom of Daboia siamensis (Myanmar viper) which is neurotoxic, myotoxic and cytotoxic was detected. Presence of Daboxin P, which is a major protein in the venom of Indian Daboia russelii with strong anticoagulant activity, was also observed. Inconsistent distribution of such lethal toxins in the venom of same species calls for more investigations of snake venoms from lesser explored regions and formulation of better alternatives to the current antivenom therapy for efficient treatment.

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.

Russell Viper Venom: A Journey from the Bedside to the Bench and Back to the Bedside.

Russell Viper Venom (RVV) is widely used as a diagnostic test for antiphospholipid syndrome (APS). But the history of how this venom came to be discovered is well known. Dr Patrick Russell is responsible for the identification of the venom during his work on snake bites in India while Dr Robert Macfarlane used it to staunch bleeding in persons with haemophilia. The ability to directly activate factor X led RVV to the laboratory diagnosis of APS. More recently, it has come back to clinical world with a potential for an engineered factor X activator from RVV to be used in the treatment of haemophilia.

Changes in attachment and metabolic activity of rat neonatal cardiomyocytes and nonmyocytes caused by Macrovipera lebetina obtusa venom.

The Caucasian viper Macrovipera lebetina obtusa (MLO) is one of the most prevalent and venomous snakes in the Caucasus and the surrounding regions, yet the effects of MLO venom on cardiac function remain largely unknown. We examined the influence of MLO venom (crude and with inhibited metalloproteinases and phospholipase A2) on attachment and metabolic activity of rat neonatal cardiomyocytes (CM) and nonmyocytes (nCM), assessed at 1 and 24 h. After exposing both CM and nCM to varying concentrations of MLO venom, we observed immediate cytotoxic effects at a concentration of 100 µg/ml, causing detachment from the culture substrate. At lower MLO venom concentrations both cell types detached in a dose-dependent manner. Inhibition of MLO venom metalloproteinases significantly improved CM and nCM attachment after 1-hour exposure. At 24-hour exposure to metalloproteinases inhibited venom statistically significant enhancement was observed only in nCM attachment. However, metabolic activity of CM and nCM did not decrease upon exposure to the lower dose of the venom. Moreover, we demonstrated that metalloproteinases and phospholipases A2 are not the components of the MLO venom that change metabolic activity of both CM and nCM. These results provide a valuable platform to study the impact of MLO venom on prey cardiac function. They also call for further exploration of individual venom components for pharmaceutical purposes.

Immunoreactivity and neutralization efficacy of Pakistani Viper Antivenom (PVAV) against venoms of Saw-scaled Vipers (Echis carinatus subspp.) and Western Russell's Vipers (Daboia russelii) from the Indian subcontinent.

Snakebite envenoming (SBE) is a priority Neglected Tropical Disease listed by the World Health Organization. South Asia is heavily affected, and virtually all countries in the region import polyvalent antivenom products from India for clinical use. The imported antivenoms, however, have suboptimal effectiveness due to geographical venom variation. Recently, a domestic bivalent product, named Pakistani Viper Antivenom (PVAV) has been developed specifically for Pakistani vipers, Echis carinatus sochureki and Daboia russelii. As a bivalent viperid antivenom, it is unknown yet if PVAV exhibits higher immunological binding and neutralization activities against viper venoms from distant locales compared with polyvalent antivenoms manufactured in India. This study thus examined the preclinical efficacy of PVAV against venoms of Western Russell's Vipers and Saw-scaled Viper subspecies from selected locales in the Indian subcontinent. PVAV generally outperformed the commonly used VINS polyvalent antivenom (VPAV, manufactured in India) in binding toward venoms, and showed superior or comparable neutralization efficacy against the venom procoagulant and hemorrhagic effects of Saw-scaled Vipers as well as Russell's Vipers from Pakistan and Sri Lanka. Based on normalized potency values, PVAV is far more potent than VPAV in neutralizing the lethality of all viper venoms, except that of the Indian Russell's Viper. The study shows conserved antigenicity of toxins responsible for major toxicity across these viperid venoms, and suggests the feasible production of a viper-specific antivenom with higher potency and broader geographical utility for the region.

Prolonged venom-induced consumptive coagulopathy following Mangshan pit viper (Protobothrops mangshanensis) envenomation despite Hemato Polyvalent antivenom administration.

This case report summarizes an envenomation by the Mangshan pit viper (Protobothrops mangshanensis), a rare, endangered, venomous snake endemic to Mount Mang of China, and the first reported use of Hemato Polyvalent antivenom (HPAV) for this species. The snakebite occurred in a United States zoo to a 46-year-old male zookeeper. He presented via emergency medical services to a tertiary center after sustaining a single P. mangshanensis bite to the abdomen and was transported with antivenom from the zoo. Within 2 hours of envenomation, he developed oozing of sanguineous fluid and ecchymosis at the puncture site, and about 4 hours post-bite, was treated with HPAV. His coagulation profile fluctuated with the following pertinent peak/nadir laboratory values and corresponding hospital day (HD): undetectable fibrinogen levels, d-dimer 8.89 mg/L and 7.43 mg/L, and INR 2.97 and 1.46 on HD zero and three, respectively. Other peak/nadir values included hemoglobin 9.7 g/dL and creatinine phosphokinase 2410 U/L on HD four and platelets 81 × 109/L on HD seven. The patient received a total of 30 vials of HPAV over 5 days and 1 unit of cryoprecipitate on HD six. Upon discharge on HD eight, laboratory studies were normalizing, except for platelets, and edema stabilized. This case describes an acute, recurrent, and prolonged venom-induced consumptive coagulopathy despite prompt administration and repeated doses of HPAV.

Cold Finger: Raynaud Phenomenon Following Snakebite Envenoming by Nikolsky's Viper (Vipera berus nikolskii).

A field biologist was bitten by a female Nikolsky's viper (Vipera berus nikolskii) in Kharkiv Oblast, Ukraine. Two months later, the patient began to experience cold-induced vasospasm of the affected digit diagnosed as acquired Raynaud phenomenon. The patient had more than 30 occurrences during the single winter following the bite, but the signs and symptoms of Raynaud phenomenon disappeared with the end of winter. This report describes the case and puts it into context with the literature on the topic of toxin-induced peripheral vasospastic disorders and their potential importance in snakebite envenoming.

Serum Cholesterol Concentration on Admission in 415 Dogs Envenomated by Daboia (Vipera) palaestinae as a Marker of Envenomation Severity and Outcome-A Retrospective Study.

Daboia (Vipera) palaestinae (Dp), accounts for most envenomations in humans and dogs in Israel. In humans envenomed by Dp, serum cholesterol concentration (sChol) is inversely correlated with envenomation severity. This study examined the utility of sChol upon admission in dogs envenomed by Dp as an envenomation severity and outcome marker. Data upon admission, including sChol, were retrospectively collected from the medical records of dogs with proven Dp envenomation. The study included 415 dogs. The mortality rate was 11%. The heart rate upon admission was higher in non-survivors than in survivors. Signs of bleeding or hematoma and circulatory shock signs were more frequent among non-survivors compared to survivors. sChol, the platelet count, and serum albumin concentration (sAlb) were lower, while serum creatinine concentration was higher among non-survivors. sChol and sAlb were moderately, positively, and significantly correlated. sChol was significantly, negatively, albeit weakly, correlated with the length of hospitalization and the heart rate. sChol was lower in dogs admitted >12 h post-envenomation than in those admitted later. In dogs, sChol upon admission is a potential marker of severity and outcome of Dp envenomation. The platelet count, sAlb, and sCreat might also be potential markers.

Long-term health manifestations of hump-nosed pit viper (Genus: Hypnale) bites.

INTRODUCTION: The hump-nosed pit viper (Genus: Hypnale) is a highly medically significant snake in Sri Lanka, responsible for the majority of venomous snakebites (22-77%). They are found throughout Sri Lanka and the Western Ghats region of India. The venom can lead to two types of effects: acute and long-term. Acutely, bites often result in local symptoms, with less common systemic effects such as acute kidney injury, venom-induced consumption coagulopathy, and thrombotic microangiopathy. METHODS: We conducted a prospective observational study at Teaching Hospital Ratnapura, Sri Lanka, spanning six years, starting in June 2015. Patients bitten by hump-nosed pit vipers were followed up for two years, with assessments every three months to identify long-term effects. Data was gathered through interviewer-administered questionnaires. RESULTS: Out of 728 patients bitten by hump-nosed pit vipers, 22 (3%) were lost to follow-up. Forty-four (6.2%) experienced long-term effects, including chronic kidney disease (24; 3.4%), chronic wounds (five; 0.7%), amputations (five; 0.7%), fasciotomy-related wounds (four; 0.6%), and psychological illnesses (four; 0.6%). There were nine (1.3%) deaths in this group. Among those with chronic effects, 27 (61%) were males, and 17 (39%) were females, with ages ranging from 29 to 82 years (mean 57.6 years). The time it took to diagnose acute kidney injury from the snakebite was 18 h (interquartile range: 15-23.5 h), while the time to diagnose chronic kidney disease was 69 days (interquartile range: 64-74.75 days). In these patients, the estimated glomerular filtration rate was 29.3 mL/min/1.73 m2 (interquartile range: 14-50.75 mL/min/1.73 m2). Among the patients who did not develop long-term complications (662; 91%) 660 (90.7%) experienced local effects, and 82 (11.3%) developed systemic manifestations, including acute kidney injury in 60 (8%) and coagulopathy in 35 (5%). CONCLUSION: Following hump-nosed pit viper bites, a subset of patients may experience long-term health complications, including chronic kidney disease, chronic ulcers, amputations, fasciotomy-related wounds, and psychological illnesses, with chronic kidney disease being the most frequently observed among these manifestations.

Composition characterization of various viperidae snake venoms using MS-based proteomics N-glycoproteomics and N-glycomics.

Viperidae snake species is widely abundant and responsible for most envenomation cases in Turkey. The structural and compositional profiles of snake venom have been investigated to study the venom component variation across different species and to profile the venom biological activity variation against prey. In this context, we used proteomics, glycoproteomics and glycomics strategies to characterize the protein, glycoproteins and glycan structural and compositional profiles of various snake venoms in the Viperidae family. Moreover, we compared these profiles using the downstream bioinformatics and machine learning classification modules. The overall mass spectrometry profiles identified 144 different proteins, 36 glycoproteins and 78 distinct N-glycan structures varying in composition across the five venoms. A high amount of the characterized proteins belongs to the glycosylated protein family Trypsin-like serine protease (Tryp_SPc), Disintegrin (DISIN), and ADAM Cysteine-Rich (ACR). Most identified N-glycans have a complex chain carrying galactosylated N-glycans abundantly. The glycan composition data obtained from glycoproteomics aligns consistently with the findings from glycomics. The clustering and principal component analyses (PCA) illustrated the composition-based similarities and differences between each snake venom species' proteome, glycoproteome and glycan profiles. Specifically, the N-glycan profiles of M. xanthina (Mx) and V. a. ammodytes (Vaa) venoms were identical and difficult to differentiate; in contrast, their proteome profiles were distinct. Interestingly, the variety of the proteins across the species highlighted the impact of glycosylation on the diversity of the glycosylated protein families. This proposed high throughput approach provides accurate and comprehensive profiles of the composition and function of various Viperidae snake venoms.

Severity of a Vipera palaestinae envenomation objective findings associated with a complicated hospitalization course following a Vipera palaestinae bite.

The most common snake in Israel, responsible for most snakebites is Vipera palaestinae (VP). Envenomation signs and symptoms vary from local manifestations to systemic reactions that may end with death. Antivenom treatment, given to high-risk patients, reduces complications and mortality but carries risks. As of now, there is no standardized protocol for adults bitten by VP based on objective clinical and laboratory findings. We conducted A retrospective analysis of 159 patients admitted to two large tertiary care institutions in the center (Hadassah University Medical Center) and south (Soroka University Medical Center) of Israel with Vipera palaestinae bites during 1990-2017. Epidemiological and clinical data were extracted, and the patients were divided into two groups based on hospitalization time (over or under 48 h). 159 patients were included in this study. The average hospitalization time was 66.1 h, with 49.7% of patients admitted over 48 h. The main factors that statistically correlated with a longer hospitalization time were: Male gender, lower extremity bite, platelets lower than 150 K at presentation, leukocyte count of over 10 K at presentation and elevated D-Dimer levels. This study provides factors which are associated with a severe VP envenomation. These clinical or laboratory findings (along with accompanying clinical symptoms) are associated with a higher risk of a prolonged hospitalization with more complications and may require a more intensive treatment and monitoring.

Analytical Size Exclusion Chromatography Coupled with Mass Spectrometry in Parallel with High-Throughput Venomics and Bioassaying for Venom Profiling.

Modern analytical size exclusion chromatography (SEC) is a suitable technique to separate venom toxin families according to their size characteristics. In this study, a method was developed to separate intact venom toxins from Bungarus multicinctus and Daboia russelii venoms via analytical SEC using volatile, non-salt-containing eluents for post-column mass spectrometry, coagulation bioassaying and high-throughput venomics. Two venoms were used to demonstrate the method developed. While the venom of Bungaurs multicinctus is known to exert anticoagulant effects on plasma, in this study, we showed the existence of both procoagulant toxins and anticoagulant toxins. For Daboia russelii venom, the method revealed characteristic procoagulant effects, with a 90 kDa mass toxin detected and matched with the Factor X-activating procoagulant heterotrimeric glycoprotein named RVV-X. The strong procoagulant effects for this toxin show that it was most likely eluted from size exclusion chromatography non-denatured. In conclusion, the separation of snake venom by size gave the opportunity to separate some specific toxin families from each other non-denatured, test these for functional bioactivities, detect the eluting mass on-line via mass spectrometry and identify the eluted toxins using high-throughput venomics.

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.

A prospective observational phase IV study on effectiveness of animal derived polyclonal antibody antivenoms against West African carpet viper (Echis romani) induced coagulopathy and mortality.

Conventional polyclonal antibody antivenoms are the mainstay of snakebite therapy. They have not been proven to be efficacious in randomized placebo controlled clinical trials among severely envenomed patients. There is also paucity of evidence on effectiveness especially in routine use. The current study evaluated their effectiveness in post marketing use among those managed with and without antivenom as regards to reversal of venom induced coagulopathy defined using the 20 min Whole Blood Clotting Test [20WBCT] and in averting death. The effectiveness of antivenom was evaluated among 5467 patients predominantly envenomed by the West African carpet viper (Echis romani) at 3 hospitals in Nigeria from 2021 to 2022. Two antivenoms Echitab G (EG) and Echitab ICP Plus (EP) were able to restore normal clotting within 6 h of administration in 58.0% [95% Confidence Interval (95%CI)] (51.2-64.5%) and 91.7% (90.4-93.0%) of patients respectively. They were able to restore normal clotting within 24 h of administration in 96.9% (94.0-98.7%) and 99.0% (98.4-99.4%) of patients respectively. The Odds Ratio [OR (95%CI)] of dying among patients with positive 20WBCT who were treated with ≥1 vial of either EG or EP compared to those not treated was 0.06 (0.02-0.23) and 0.07 (0.03-0.15) respectively. This equated to antivenom protection against in-hospital mortality of 93-94% among patients with confirmed coagulopathy though the benefit appeared abrogated among those without coagulopathy. The untreated natural mortality was 15.94% (95%CI:8.24-26.74%) without antivenom therapy while the overall mortality was 84/5105 (1.65%; 95%CI:1.32-2.03%. The Number Needed to Treat (NNT) to avert a death was 7 patients among those with coagulopathy. Antivenoms were safe with mild early adverse reactions observed among 2.6% (95%CI:2.13-3.08%) of antivenom recipients. Polyclonal antibody antivenoms are effective and safe for treating coagulopathic envenomed patients in Nigeria.

Thromboelastography Use to Guide Resuscitation and Antivenom Administration after Gaboon Viper Bite.

The Gaboon viper (Bitis gabonica) is an exotic snake native to sub-Saharan Africa. Gaboon viper venom is an extremely toxic hemotoxin, causing severe coagulopathy and local tissue necrosis. These are not aggressive snakes and therefore bites involving humans are rare and there is not a substantial amount of literature documenting how to manage these injuries and resultant coagulopathies. We report a 29-year-old male presenting 3 hours after a Gaboon viper envenomation resulting in coagulopathy requiring massive resuscitation and multiple doses of antivenom. The patient received various blood products based on thromboelastography (TEG) and also underwent early continuous renal replacement therapy (CRRT) to assist in correction of severe acidosis and acute renal failure. The combination of TEG to guide resuscitation, administration of antivenom, and early implementation of CRRT allowed our team to correct venom-induced consumptive coagulopathy and ultimately allow the patient to survive following this extremely deadly Gaboon viper envenomation.