Proteomics and immunocharacterization of Asian mountain pit viper (Ovophis monticola) venom

Comparative in vitro immunoreactivity and protein analysis of Trimeresurus albolabris and Tropidolaemus wagleri venoms

Snakebite envenomation remains a significant global health concern, with antivenoms being the primary treatment. However, variations in venom composition can affect antivenom efficacy, leading to differences in immunoreactivity. This study aimed to evaluate and compare the immunological reactivity of venom components in Trimeresurus albolabris and Tropidolaemus wagleri venoms and further investigate the differences in antigenic properties of a key protein between two species that may influence antivenom recognition. The levels of immunological reactivity of monovalent (homospecific) antivenom and hemato polyvalent antivenom to Trimeresurus albolabris and Tropidolaemus wagleri venoms were evaluated using indirect ELISA. The immunoreactive levels of both antivenoms to antigenic proteins in Trimeresurus albolabris venom were comparable. In addition, both antivenoms reacted immunologically with antigens in Tropidolaemus wagleri venom. However, the hemato polyvalent antivenom showed greater reactivity to Tropidolaemus wagleri venom than the monovalent antivenom. The overall reactivity of the antivenoms to Trimeresurus albolabris venom was higher than that to Tropidolaemus wagleri venom. Using two-dimensional (2DE) immunoblotting and liquid chromatography mass-spectrometry-based proteomic technology (LC-MS/MS), immunoreactive and non-reactive proteins in both pit viper venoms were characterized and identified. Trimeresurus albolabris venom comprised a total of 235 spots, while Tropidolaemus wagleri venom contained 72 spots. Immunorecognition between the polyvalent antivenom and specific proteins in both venoms was mostly detected in proteins with a size over 30 kDa. Among the nine protein families identified in both venoms, the most frequently reactive proteins found in Trimeresurus albolabris venom were snake venom metalloproteinases (SVMP) and snake venom serine proteases (SVSP), while in Tropidolaemus wagleri venom, the most frequent were members of the L-amino acid oxidase (LAAO) family. For the non-immunoreactive proteins, we detected the highest identity numbers of phospholipase A2 (PLA2) in Trimeresurus albolabris venom and SVSP in Tropidolaemus wagleri venom. The distinctive characteristics between the non-reactive SVSP in Tropidolaemus wagleri venom and the reactive SVSP in Trimeresurus albolabris venom were investigated. The antigenic properties and predicted B cell epitopes were further analyzed using a computational approach. Structural and physicochemical analyses indicated that Loop 2 (residues 100-110) in the immunoreactive SVSP from Trimeresurus albolabris venom exhibited higher hydrophilicity and surface accessibility compared to the non-immunoreactive SVSP from Tropidolaemus wagleri venom. These findings provide important insights into the differences in antivenom reactivity to specific proteins across different snake venoms and may contribute to future research aimed at optimizing antivenom formulations.

Proteomic and functional characterisation of Trimeresurus popeiorum (Pope's pit viper) venom proteins: Role of enzymatic and non-enzymatic venom toxins in envenomation pathophysiology

Snakebite remains a significant public health issue in tropical regions, with 4.5 to 5.4 million incidents annually. Trimeresurus popeiorum (Pope's Pit Viper), found in Southeast Asia and northeast India, poses a potential threat, yet its venom's protein composition and toxicity are poorly understood. In this study, we used label-free quantitative proteomics to analyze the venom of T. popeiorum, identifying 106 proteins across 12 venom protein families. Notably, 60 % of the venom consisted of proteolytic enzymes, correlating with its prominent metalloprotease, fibrin(ogen)lytic, procoagulant, and thrombin-like activities. The proteome composition also correlates with the clinical effects such as consumption coagulopathy and local effects, seen in victims of Pit Viper envenomation in northeast India. Our findings suggest that T. popeiorum venom is less toxic than other Viperinae species such as Daboia russelii and Echis carinatus, likely due to isoform-level variations in certain toxin classes, including metalloprotease and serine protease. The venom's lethal dose (LD50) in Swiss albino mice was 1 mg/kg, and it caused haemorrhage, tissue necrosis, edema, myotoxicity, and defibrinogenation. Histopathological examination of the TPV-treated mice showed notable toxic effects, including marked hepatic vacuolation in the liver, damage to cardiac muscle and vascular congestion in the heart, bronchial epithelial hyperplasia with cellular infiltration in the interstitial and peribronchiolar regions of the lungs, as well as tubular necrosis and haemorrhage in the kidneys. This research provides the first comprehensive analysis of T. popeiorum venom, highlighting its pharmacological effects and the need for greater medical attention to this lesser-known species.

A Single-Center Review of Cases to Understand the Indian Polyvalent Antivenom Use in Hump-Nosed Pit Viper Bites in South India

Introduction

India, with nearly 60 venomous snake species, has just one commercially available antivenom, the Indian polyvalent antivenom (IPAV). The hump-nosed pit viper (Hypnale hypnale), an indigenous venomous snake, causes considerable morbidity and at time mortality for which we have no commercially available antivenom. However, most clinicians rely purely on the clinical syndromes and end up using the available IPAV for H. hypnale envenomation.

Methods

Between April 2017 and December 2022, we reviewed 41 cases of H. hypnale envenomation, comparing clinical and laboratory profiles of patients who received IPAV with those who did not.

Results

Local signs of envenomation were seen in 39 (95.12%) cases, with the most common being edema or swelling at the bite site. Eight (19.5%) patients developed coagulopathy, and two developed renal failure during their hospital stay. Among the 39 envenomated individuals, 13 received polyvalent snake antivenom. Over half of those receiving antivenom had hypersensitivity reactions. Patients who received antisnake venom (ASV) had increased intensive care unit stay, duration of hospitalization, and hospital expenses as compared to patients who did not. There was one death among the patients who received antivenom.

Conclusion

H. hypnale viper envenomation is associated with local and systemic signs of envenomation, with coagulopathy being a common complication. Administering the current polyvalent antivenom to victims of H. hypnale bites did not reduce the morbidities or prevent mortality; instead, it exposes them to additional risks associated with ASV administration.

A case report of Ovophis monitcola (Mountain pit-viper) envenoming in northeastern India resulting in prolonged coagulopathy

India is home to a diverse spectrum of medically-significant snakes accounting for the world's largest burden of envenoming, morbidity and mortality. Indian polyspecific antivenom is derived from the venom of four snake species (Daboia russelii, Echis carinatus, Naja naja and Bungarus caeruleus), considered to be responsible for the majority of snakebite morbidity and mortality. The treatment of venomous bites from other less-commonly encountered venomous snake species can be challenging. In this report, we describe the case of a 32-year-old male who presented with features of local cytotoxicity and coagulopathy following a bite from Ovophis monitcola (mountain pit-viper) in Nagaland, northeast India. Local and systemic envenoming, confirmed by bedside and laboratory based clotting assays, failed to respond to polyspecific antivenom and venom-induced consumption coagulopathy persisted for 28 days. Remote consultation with a national Poison Control Centre helped establish the responsible snake species and guide appropriate medical management.

Full sequencing and comparison of five venom metalloproteases of Trimeresurus gracilis: The PI-enzyme is most similar to okinalysin but the PIII-enzyme is most similar to Crotalus venom enzymes

The cDNAs encoding the Zn⁺²-metalloproteases (SVMPs) of Trimeresurus gracilis (abbreviated as Tgc), a pitviper endemic to Taiwan, were cloned from venom glands and sequenced. The amino-acid sequences of five novel SVMPs, including one P-III, three P-II and one P-I class enzymes, were thus deduced and subjected to BLAST-analyses. The P-III enzyme (designated as Tgc-PIII) is structurally most similar to the PIII-SVMPs of New World pitvipers but not similar to the PIII-SVMP of Ovophis okinavensis. Sequence-similarity analysis of 22 homologous PIII-SVMPs reveal three major structural subtypes of the pitviper PIII-SVMPs, which possibly have different substrate specificities. In addition, Tgc-PIII and the PI-class SVMP (named Tgc-MP) were isolated from the venom and verified by mass spectrometry. All the three deduced sequences of PII-SVMPs (Tgc-PIIs) contain an abnormal Zn⁺²-binding-site in their catalytic-domain, and an identical "long-disintegrin" domain. The predicted 85-residues disintegrin, gracilisin, bears high similarities to some long-disintegrins of the New-World pitvipers and salmosin3. By BLAST search and comparison, Tgc-MP is 96% similar to okinalysin, the hemorrhagic PI-SVMP of O. okinavensis, rather than any other PI-SVMPs in the databanks. Our results confirm the fast evolution of Tgc-SVMPs as well as their structural similarities to different SVMP-classes of the New-World pitvipers and of O. okinavensis, respectively. The implications of our findings are discussed along with our previous sequence comparisons of venom phospholipases A₂ and ten venom serine proteases of Tgc.

Case Report: Management of an Uncommon Crotaline Snakebite (Ovophis makazayazaya)

Ovophis makazayazaya bite is an uncommon cause of snakebite that humans may sustain as a result of the continuous overexploitation of forest habitats and excessive development in Taiwan. Although the Taiwanese government has produced four antivenoms against medically important snakebite accidents, O. makazayazaya is not among the snakes for which an antivenom has been produced. A case of O. makazayazaya snakebite on a patient's right foot, which later swelled into the hip, is reported. In vitro studies have reported that monovalent antivenoms for Gloydius brevicaudus and Trimeresurus albolabris, and polyvalent antivenom for Calloselasma rhodostoma, Daboia siamensis, and T. albolabris show reactivity toward Ovophis venoms. However, these antivenoms are unavailable in Taiwan. Thus, bivalent antivenom for Trimeresurus stejnegeri stejnegeri and Protobothrops mucrosquamatus was used, assuming similar immunoreactivity and a possible para-specific effect of green pit viper antivenom against this Ovophis venom. A favorable outcome was observed, without significant extension in prothrombin time and activated partial thromboplastin time. In addition, no systemic bleeding occurred. Nonetheless, further venom and antivenom evaluations should ascertain the efficacy of this para-specific antivenoms against this crotaline snakebite.

Separation and Analytical Techniques Used in Snake Venomics: A Review Article

The deleterious consequences of snake envenomation are due to the extreme protein complexity of snake venoms. Therefore, the identification of their components is crucial for understanding the clinical manifestations of envenomation pathophysiology and for the development of effective antivenoms. In addition, snake venoms are considered as libraries of bioactive molecules that can be used to develop innovative drugs. Numerous separation and analytical techniques are combined to study snake venom composition including chromatographic techniques such as size exclusion and RP-HPLC and electrophoretic techniques. Herein, we present in detail these existing techniques and their applications in snake venom research. In the first part, we discuss the different possible technical combinations that could be used to isolate and purify SV proteins using what is known as bioassay-guided fractionation. In the second part, we describe four different proteomic strategies that could be applied for venomics studies to evaluate whole venom composition, including the mostly used technique: RP-HPLC. Eventually, we show that to date, there is no standard technique used for the separation of all snake venoms. Thus, different combinations might be developed, taking into consideration the main objective of the study, the available resources, and the properties of the target molecules to be isolated.