Structures and Functions of Snake Venom Metalloproteinases (SVMP) from Protobothrops venom Collected in Japan

Atrase A, a P-III class metalloproteinase purified from cobra venom, exhibits potent anticoagulant activity by inhibiting coagulation pathway and activating the fibrinolytic system

Snake venoms, comprising a complex array of protein-rich components, an important part of which are snake venom metalloproteinases (SVMPs). These SVMPs, which are predominantly isolated from viperid venoms, are integral to the pathology of snakebites. However, SVMPs derived from elapid venoms have not been extensively explored, and only a handful of SVMPs have been characterized to date. Atrase A, a nonhemorrhagic P-III class metalloproteinase from Naja atra venom, exhibits weak proteolytic activity against fibrinogen in vitro but has pronounced anticoagulant effects in vivo. This contrast spurred investigations into its anticoagulant mechanisms. Research findings indicate that atrase A notably extends the activated partial thromboplastin time, diminishes fibrinogen levels, and impedes platelet aggregation. The anticoagulant action of atrase A primarily involves inhibiting coagulation factor VIII and activating the endogenous fibrinolytic system, which in turn lowers fibrinogen levels. Additionally, its effect on platelet aggregation further contributes to its anticoagulant profile. This study unveils a novel anticoagulant mechanism of atrase A, significantly enriching the understanding of the roles of cobra venom metalloproteinases in snake venom. Furthermore, these findings underscore the potential of atrase A as a novel anticoagulant drug, offering insights into the functional evolutions of cobra venom metalloproteinases.

Evaluation of venom diversity and antivenom quality from the venom of long-term captive vs recently wild captured Pseudocerastes persicus snake: An In vitro and In vivo study

Snakebite envenomation is a life-threatening condition and antivenoms are used as the most effective treatment. Venom obtained from snakes in long-term captivity showed some variations in comparison to the venom of the wild snakes. The objective of this study is to compare the venom of the Pseudocerastes persicus under long-term captivity and wild conditions as well as the antivenom obtained from these venoms. We have analyzed venom samples and produced trivalent antivenoms using the venom of long-term captive (LTC) or recently wild-captured (RWC) Pseudocerastes persicus, and RWC Macrovipera lebetina, and Echis carinatus. The HPLC analysis revealed that the RWC snakes' venom had three peaks that were not present in the LTC snake's venom. Further analysis using MALDI-TOF and MS/MS showed that the fraction with a retention time (RT) of 14 min contained a toxin from the Kunitz-type serine protease inhibitor (KUT) class, while the fraction with RT 21 a peptide identified within the snake venom metalloproteinase (SVMP) class. The third peak was identified as a sphingolipid. Interestingly, the in vivo preclinical tests showed no significant differences in the effectiveness of the antivenoms. which could be due to the cross-immunogenicity or cross-reactivity between different toxins in the venom. According to our results, small variations in the venom composition of a species do not lead to a decrease in the efficacy of the polyvalent antivenom.

Cobra venom P-III class metalloproteinase atrase a induces inflammatory response and cell apoptosis in endothelial cells via its metalloproteinase domain

Snake venom metalloproteinases (SVMPs), which are a critical component of viperid and crotalid venoms, play various important roles in the pathogenesis of snakebite envenomation. The SVMPs from elapid venoms are not well elucidated, as compared with those from viperid and crotalid venoms. Atrase A is a nonhemorrhagic P-III SVMP purified from Naja atra venom that possesses only weak fibrinogenolytic activity. In our prior study, we found that atrase A detached adherent cells from the substrate. In this work, we investigated further the effect and mechanism of atrase A on endothelial cells. Oxidative damage, inflammatory mediators, apoptosis, and activation of the NF-κB and MAPK signaling pathways were measured after HMEC-1 cells were exposed to atrase A. The results showed that HMEC-1 cells released inflammatory mediators, exihibited oxidative damage and apoptosis after exposure to atrase A. The Western blot analysis results revealed that atrase A increased Bax/Bcl-2 and caspase-3 levels and activated the NF-κB and MAPK signaling pathways in endothelial cells. The effects on endothelial cells were nearly completely abolished after atrase A was treated with ethylenediamine tetraacetic acid. These results showed that atrase A led to an inflammatory response, cellular injury and apoptosis in endothelial cells, and this effect was due to its metalloproteinase domain. The study contributes to a better understanding of the structures and functions of cobra venom P-III class metalloproteinases.

A comparative analysis of the proteomes and biological activities of the venoms from two sea snakes, Hydrophis curtus and Hydrophis cyanocinctus, from Hainan, China

We characterized and compared the venom protein profiles of Hydrophis curtus (synonyms: Lapemis hardwickii, Lapemis curtus and Hydrophis hardwickii) and Hydrophis cyanocinctus, the two representatives of medically important venomous sea snakes in Chinese waters using proteomic approaches. A total of 47 and 38 putative toxins were identified in H. curtus venom (HcuV) and H. cyanocinctus venom (HcyV), respectively, and these toxins could be grouped into 15 functional categories, mainly proteinases, phospholipases, three-finger toxins (3FTxs), lectins, protease inhibitors, ion channel inhibitors, cysteine-rich venom proteins (CRVPs) and snake venom metalloproteases (SVMPs). The constituent ratio of each toxin category varied between HcuV and HcyV with 3FTx (54% in HcuV/69% in HcyV) and PLA2 (38% in HcuV/22% in HcyV) unanimously ranked as the top two most abundant families. Both HcuV and HcyV exhibited relatively high lethality (LD₅₀ values in mice of 0.34 μg/g and 0.24 μg/g, respectively), specific PLA2 activity and hemolytic activity. On the basis of several previous reports of HcuV and HcyV collected from other areas, these findings greatly expand our understanding of geographical variation and interspecies diversity of the two sea snake venoms and can provide a scientific basis for the development of specific sea snake antivenom in the future.

Nanobodies as novel therapeutic agents in envenomation

BACKGROUND

An effective therapy against envenoming should be a priority in view of the high number scorpion stings and snakebites. Serum therapy is still widely applied to treat the envenomation victims; however this approach suffers from several shortcomings. The employment of monoclonal antibodies might be an outcome as these molecules are at the core of a variety of applications from protein structure determination to cancer treatment. The progress of activities in the twilight zone between genetic and antibody engineering have led to the development of a unique class of antibody fragments. These molecules possess several benefits and lack many possible disadvantages over classical antibodies. Within recombinant antibody formats, nanobodies or single domain antigen binding fragments derived from heavy chain only antibodies in camelids occupy a privileged position.

SCOPE OF REVIEW

In this paper we will briefly review the common methods of envenomation treatment and focus on details of various in vivo research activities that investigate the performance of recombinant, monoclonal nanobodies in venom neutralization.

MAJOR CONCLUSIONS

Nanobodies bind to their cognate target with high specificity and affinity, they can be produced in large quantities from microbial expression systems and are very robust even when challenged with harsh environmental conditions. Upon administering, they rapidly distribute throughout the body and seem to be well tolerated in humans posing low immunogenicity.

GENERAL SIGNIFICANCE

Scorpion and snake envenomation is a major issue in developing countries and nanobodies as a venom-neutralizing agent can be considered as a valuable and promising candidate in envenomation therapy.

Comprehensive Snake Venomics of the Okinawa Habu Pit Viper, Protobothrops flavoviridis, by Complementary Mass Spectrometry-Guided Approaches

The Asian world is home to a multitude of venomous and dangerous snakes, which are used to induce various medical effects in the preparation of traditional snake tinctures and alcoholics, like the Japanese snake wine, named Habushu. The aim of this work was to perform the first quantitative proteomic analysis of the Protobothrops flavoviridis pit viper venom. Accordingly, the venom was analyzed by complimentary bottom-up and top-down mass spectrometry techniques. The mass spectrometry-based snake venomics approach revealed that more than half of the venom is composed of different phospholipases A2 (PLA₂). The combination of this approach and an intact mass profiling led to the identification of the three main Habu PLA₂s. Furthermore, nearly one-third of the total venom consists of snake venom metalloproteinases and disintegrins, and several minor represented toxin families were detected: C-type lectin-like proteins (CTL), cysteine-rich secretory proteins (CRISP), snake venom serine proteases (svSP), l-amino acid oxidases (LAAO), phosphodiesterase (PDE) and 5'-nucleotidase. Finally, the venom of P. flavoviridis contains certain bradykinin-potentiating peptides and related peptides, like the svMP inhibitors, pEKW, pEQW, pEEW and pENW. In preliminary MTT cytotoxicity assays, the highest cancerous-cytotoxicity of crude venom was measured against human neuroblastoma SH-SY5Y cells and shows disintegrin-like effects in some fractions.