The establishment and evaluation of a swine model of deinagkistrodon acutus snakebite envenomation

OBJECTIVE

To establish a preclinical large-animal model of Deinagkistrodon acutus snakebite envenomation and evaluate its feasibility.

METHODS

The venom of D. acutus (0 mg/kg, 1 mg/kg, 2 mg/kg, 5 mg/kg, or 10 mg/kg) was injected into the left biceps femoris of 11 male pigs. Then, the circumferences of the limbs were regularly measured, and changes in muscle injury biomarkers, blood parameters, coagulation function, vital organ function and injury biomarkers were regularly detected. At 24 h after venom injection, the animals were euthanized, and the pathological damage to the vital organs mentioned above was evaluated.

RESULTS

The two pigs receiving 10 mg/kg and 5 mg/kg snake venom died at 8 h and 12 h after injection, respectively. The remaining pigs were equally divided into 0 mg/kg, 1 mg/kg, and 2 mg/kg snake venom groups, and all of them survived to 24 h after injection. Compared with the pigs receiving 0 mg/kg snake venom, the pigs receiving 1 mg/kg or 2 mg/kg snake venom exhibited significant abnormities, including limb swelling; increased muscle injury biomarker creatine kinase (CK) and coagulation function indicators prothrombin time and D-dimer; and decreased blood routine indicator platelet and coagulation function indicator fibrinogen. Moreover, significant abnormalities in myocardial and cerebral function and injury biomarkers in the heart, brain, liver, kidney and intestine were also observed. In particular, the abnormalities mentioned above were significantly obvious in those pigs receiving 2 mg/kg snake venom. Pathological evaluation revealed that the morphology of muscle, heart, brain, liver, kidney, and intestine in those pigs receiving 0 mg/kg snake venom was normal; however, pathological damage was observed in those pigs receiving 1 mg/kg and 2 mg/kg snake venom. Similarly, the pathological damage was more severe in those pigs receiving 2 mg/kg snake venom.

CONCLUSION

The intramuscular injection of 2 mg/kg D. acutus venom seems to be an optimal dose for examining the preclinical efficacy of existing and novel therapeutics for treating D. acutus envenomation in pigs.

The anti-myotoxic effects and mechanisms of Sinonatrix annularis serum and a novel plasma metalloproteinase inhibitor towards Deinagkistrodon acutus envenomation

Non-venomous snakes commonly evolve natural resistance to venom to escape predators. Sinonatrix annularis serum has been shown to inhibit Deinagkistrodon acutus venom-induced hemorrhage and upregulation of serum CK, CK-MB, LDH, AST and ALT levels. Using TMT-labeled proteomics analysis, 168 proteins were found to be altered significantly in the envenomed gastrocnemius muscle and categorized into pathways such as complement and coagulation cascades, leukocyte transendothelial migration, and JAK/STAT signaling. These alterations were mitigated by S. annularis serum. Subsequently, a novel metalloproteinase inhibitor, SaMPI, was isolated from S. annularis serum by two-step chromatography. It showed strong antidotal effects against D. acutus envenomation, including inhibition of subcutaneous bleeding caused by crude venom and DaMP (a metalloproteinase derived from D. acutus) activity in a 1:1 ratio. Histology and immunoblotting analyses demonstrated that SaMPI mitigated myonecrosis, reduced neutrophil infiltration and local inflammatory factor release, and retarded JAK/STAT and MAPK signaling activation. Analysis of the SaMPI gene cloned by 5'-RACE revealed a shared sequence identity of 58-79% with other SVMP inhibitors. These findings demonstrate the protective effects of SaMPI and indicate its potential value as a candidate for viper bite adjuvant therapy.

[A case of poisoning caused by head and face bite of Deinagkistrodon acutus]

Snake bites kill and maim many people every year. Head and face venomous snake bite is rare, easy to misdiagnose and miss diagnosis, and the fatality rate is high. In this paper, 1 case of head and face venomous snake bite poisoning was reported and 10 similar cases were reviewed. The clinical characteristics of head and face venomous snake bite poisoning were summarized to provide guidance for clinical diagnosis and treatment. Head and face venomous snake bites may lead to airway injury, edema, and airway obstruction is the main cause of early death. Timely intubation or tracheotomy to maintain oxygen supply and early use of antivenin can improve prognosis.

Immunoprofiling of Equine Plasma against Deinagkistrodon acutus in Taiwan: Key to Understanding Differential Neutralization Potency in Immunized Horses

Snakebite envenoming is a public health issue linked to high mortality and morbidity rates worldwide. Although antivenom has been the mainstay treatment for envenomed victims receiving medical care, the diverse therapeutic efficacy of the produced antivenom is a major limitation. Deinagkistrodon acutus is a venomous snake that poses significant concern of risks to human life in Taiwan, and successful production of antivenom against D. acutus envenoming remains a considerable challenge. Among groups of horses subjected to immunization schedules, few or none subsequently meet the quality required for further scale-up harvesting. The determinants underlying the variable immune responses of horses to D. acutus venom are currently unknown. In this study, we assessed the immunoprofiles of high-potency and low-potency horse plasma against D. acutus venom and explored the conspicuous differences between these two groups. Based on the results of liquid chromatography with tandem mass spectrometry (LC-MS/MS), acutolysin A was identified as the major component of venom proteins that immunoreacted differentially with the two plasma samples. Our findings indicate underlying differences in antivenoms with variable neutralization efficacies, and may provide valuable insights for improvement of antivenom production in the future.

Molecular quantification, a new strategy for quality control of Chinese patent medicine containing animal-derived crude drug: Qi She in Jinlong capsule as an example

Quality control for Chinese patent medicine (CPM) containing animal-derived crude drug(s) is rather difficult. The methods based on chemical composition analysis, which are commonly used in CPM consisted of plant-derived crude drugs, are often not applicable for CPM containing animal-derived crude drug, because the effective constituents of most animal-derived crude drugs remain unknown. Even if there are such methods, they are usually qualitative rather than quantitative, and the specificity is generally poor. Here we proposed a molecular quantification method for CPM containing animal-derived crude drug, based upon the hypothesis that the amount of remnant DNA fragments could reflect feeding quantity of the crude drugs and thus ensure the quality of the CPM. Take Jinlong capsule [a hepatocellular carcinoma-resisting Chinese patent medicine comprising of three fresh animal drugs, i.e. Shougong (Peking gecko, Gekko swinhonis), Qi She (sharp-snouted pitviper, Deinagkistrodon acutus), and Jinqian Baihua She (many-banded krait, Bungarus multicinctus)] as an example, we established a qPCR assay for Qi She in the capsule, which verified the feasibility of the quality control method based on molecular quantification. Species-specific primers and TaqMan probe for Qi She were designed, and the qPCR assay system was then established. The assay exhibited a good specificity; there's a good linearity between Ct values and logarithm of the target amplicon copy numbers within the range of 8.8 × 10¹ to 8.8 × 10⁶ copies/μL, and the limit of detection was 88 copies/μL. The method was validated through reproducibility, stability assessment. Recovery of spiked samples was between 91.59% and 101.69%. It was verified that the copy numbers reflected the original feeding amount of an animal-derived crude drug by self-made Jinlong capsules. The assay was successfully applied in Qi She-specific amplicon determination in 20 batches of Jinlong capsule. The study was expected to provide a new strategy for quality control of CPM containing animal-derived crude drug.

Exploring the five-paced viper (Deinagkistrodon acutus) venom proteome by integrating a combinatorial peptide ligand library approach with shotgun LC-MS/MS

BACKGROUND

Snake venoms are complex mixtures of toxic proteins or peptides encoded by various gene families that function synergistically to incapacitate prey. In the present study, in order to unravel the proteomic repertoire of Deinagkistrodon acutus venom, some trace abundance components were analyzed.

METHODS

Shotgun proteomic approach combined with shotgun nano-LC-ESI-MS/MS were employed to characterize the medically important D. acutus venom, after collected samples were enriched with the combinatorial peptide ligand library (CPLL).

RESULTS

This avenue helped us find some trace components, undetected before, in D. acutus venom. The results indicated that D. acutus venom comprised 84 distinct proteins from 10 toxin families and 12 other proteins. These results are more than twice the number of venom components obtained from previous studies, which were only 29 distinct proteins obtained through RP-HPLC for the venom of the same species. The present results indicated that in D. acutus venom, the most abundant components (66.9%) included metalloproteinases, serine proteinases, and C-type lectin proteins; the medium abundant components (13%) comprised phospholipases A2 (PLA2) and 5'-nucleotidases and nucleases; whereas least abundant components (6%) were aminopeptidases, L-amino acid oxidases (LAAO), neurotoxins and disintegrins; and the trace components. The last were undetected before the use of conventional shotgun proteomics combined with shotgun nano-LC-ESI-MS/MS, such as cysteine-rich secretory proteins Da-CRPa, phospholipases B-like 1, phospholipases B (PLB), nerve growth factors (NGF), glutaminyl-peptide cyclortransferases (QC), and vascular non-inflammatory molecules 2 (VNN2).

CONCLUSION

These findings demonstrated that the CPLL enrichment method worked well in finding the trace toxin proteins in D. acutus venom, in contrast with the previous venomic characterization of D. acutus by conventional LC-MS/MS. In conclusion, this approach combined with the CPLL enrichment was effective for allowing us to explore the hidden D. acutus venomic profile and extended the list of potential venom toxins.

DAKS1, a Kunitz Scaffold Peptide from the Venom Gland of Deinagkistrodon acutus Prevents Carotid-Artery and Middle-Cerebral-Artery Thrombosis via Targeting Factor XIa

Scaffold-based peptides (SBPs) are fragments of large proteins that are characterized by potent bioactivity, high thermostability, and low immunogenicity. Some SBPs have been approved by the FDA for human use. In the present study, we developed SBPs from the venom gland of Deinagkistrodon acutus (D. acutus) by combining transcriptome sequencing and Pfam annotation. To that end, 10 Kunitz peptides were discovered from the venom gland of D. acutus, and most of which peptides exhibited Factor XIa (FXIa) inhibitory activity. One of those, DAKS1, exhibiting strongest inhibitory activity against FXIa, was further evaluated for its anticoagulant and antithrombotic activity. DAKS1 prolonged twofold APTT at a concentration of 15 μM in vitro. DAKS1 potently inhibited thrombosis in a ferric chloride-induced carotid-artery injury model in mice at a dose of 1.3 mg/kg. Furthermore, DAKS1 prevented stroke in a transient middle cerebral-artery occlusion (tMCAO) model in mice at a dose of 2.6 mg/kg. Additionally, DAKS1 did not show significant bleeding risk at a dose of 6.5 mg/kg. Together, our results indicated that DAKS1 is a promising candidate for drug development for the treatment of thrombosis and stroke disorders.

Do pit vipers assess their venom? Defensive tactics of Deinagkistrodon acutus shift with changed venom reserve

To maximize survival probability, animals must assess predation risks and adopt flexible defensive strategies based on specific conditions. Pit vipers utilize venom for predation and self-defense, and venom status significantly influences its effectiveness. Thus, pit vipers may evaluate their venom reserve and adopt corresponding defensive tactics. Twenty-three sharp-snouted pit vipers (Deinagkistrodon acutus) were grouped by different venom status and were subjected to eight behavior trials. Subjects' defensive behaviors were recorded and analyzed. Results showed that the normal venom group displayed stable responses across the trials. The low venom group showed fewer strikes and more fleeing behaviors at the end of experiments. After given prolonged intervals for replenishing the venom, significant increases of strike behaviors were observed in the replenishing venom group. These results demonstrated the capability of adopting flexible defensive tactics based on varied venom reserve and provided new evidence for venom-status-recognition.

Unexpected death in a young man associated with a unilateral swollen leg: Pathological and toxicological findings in a fatal snakebite from Deinagkistrodon acutus (Chinese moccasin)

Deinagkistrodon acutus (D. acutus), also known as the Chinese moccasin, is a viper species found throughout the southeastern parts of China, northern Vietnam and Laos. D. acutus envenomation can result in coagulopathy and lead to death if not treated correctly. A 20-year-old man was discovered with a severely swollen left thigh with overlying dark purple, discolored skin. He was immediately transported to hospital. Laboratory examinations revealed dysfunctional coagulation and fluid-electrolyte imbalances. He died 2 h later despite resuscitation efforts. Surveillance footage revealed that he had walked through a grass field while returning home that night. Autopsy and pathological examination findings revealed a large area of muscle necrosis of the left thigh, renal tubular necrosis, and hepatocyte necrosis. Potential fang marks were found on the decedent's jeans. Due to our suspicions, we performed specific enzyme-linked immunosorbent assays (ELISA) and detected D. acutus venom in the kidneys, left thigh muscle, liver, lung, spleen, and heart tissues of the decedent. In conclusion, the clinical manifestations, autopsy, histopathological examination, ELISA, and investigation results confirmed D. acutus envenomation.

Complete mitochondrial genome of the sharp-snouted pitviper Deinagkistrodon acutus (Reptilia, Viperidae)

The sharp-snouted pitviper, Deinagkistrodon acutus, belongs to the monotypic genus Deinagkistrodon of the family Viperidae. It is one of the important species of snakes for its commercial and medicinal value. Complete mitochondrial genome sequence of the D. acutus was sequenced by next-generation sequencing technology. The total mitochondrial genome is 17,538 bp in length, containing 13 protein-coding genes, 22 tRNA genes, 2 ribosome RNA genes, and 2 control regions. Most of the genes of D. acutus are encoded on the H-strand, except for the ND6 subunit gene and eight tRNA genes which distribute on the L-strand. Phylogenetic reconstruction result indicated that our newly determined mitochondrial genome sequence could meet the demands. The complete mitochondrial genome sequence presented here will be useful to study the evolutionary relationships and genetic diversity of D. acutus.

Snake venom proteome and immuno-profiling of the hundred-pace viper, Deinagkistrodon acutus, in Taiwan

Deinagkistrodon acutus, also known as the hundred-pace viper or Chinese moccasin, is a clinically significant venomous snake in Taiwan. To address the lack of knowledge on the venom proteome of D. acutus, the venom composition was studied by a bottom-up proteomic approach combining reverse phase high-performance liquid chromatography, SDS-PAGE, and LC-MS/MS analysis. The immunoreactivity and cross-reactivity of Taiwanese freeze-dried D. acutus antivenom (DA-AV) and hemorrhagic antivenom (FH-AV) were investigated, as well. The proteomic analysis revealed the presence of 29 distinct proteins from D. acutus venom belonging to 8 snake venom protein families. Snake venom metalloproteinase (SVMP, 46.86%), C-type lectin (CLEC, 37.59%), phospholipase A₂ (PLA₂, 7.33%) and snake venom serine protease (SVSP, 6.62%) were the most abundant proteins. In addition to DA-AV, FH-AV also showed a profile of broad immunorecognition toward the venom of D. acutus. Remarkably, both antivenoms specifically reacted with the HPLC fractions containing SVMPs, and the titer was 5-10 times higher than fractions of other components. This information helps us to deeply understand the pathophysiology of D. acutus envenomation and guide us to development of more effective antivenom for clinical treatment.

Clinical and laboratory features distinguishing between Deinagkistrodon acutus and Daboia siamensis envenomation

Background

There are 6 species of venomous snakes in Taiwan. Two of them, Deinagkistrodon acutus (D. acutus) and Daboia siamensis (D. siamensis), can cause significant coagulopathy. However, a significant proportion of patients with snakebites cannot identify the correct snake species after envenomation, which hampers the application of antivenom. Hence, the differential diagnosis between the two snakebites by clinical presentations is important. This study aims to compare their clinical and laboratory features for the purpose of differential diagnosis between the two snakebites.

Methods

We retrospectively reviewed the medical records of patients who arrived at the emergency department due to D. acutus or D. siamensis envenomation, between 2003 and 2016, in one medical center in eastern Taiwan. Since these snakebites are rare, we also included 3 cases reported from another hospital in central Taiwan.

Results

In total, 15 patients bitten by D. acutus and 12 patients by D. siamensis were analyzed. Hemorrhagic bulla formation and the need for surgical intervention only presented for D. acutus envenomation cases (Both 53.3% vs. 0.0%, P = 0.003). As to laboratory features, lower platelet counts (20.0 ×  10³/μL [interquartile range, 14–66 × 10³/μL] vs. 149.0 × 10³/μL [102.3–274.3 × 10³/μL], P = 0.001), lower D-dimer level (1423.4 μg/L [713.4–4212.3 μg/L] vs. 12,500.0 μg/L [2351.4–200,000 μg/L], P = 0.008), higher proportion of patients with moderate-to-severe thrombocytopenia (platelet count < 100 × 10³/μL) (80% vs. 16.7%, odds ratio (OR) = 20.0, 95% CI, 2.77–144.31; P = 0.002), and lower proportion of patients with extremely high D-dimer (> 5000 ng/mL) (16.7% vs. 66.7%, adjusted OR = 0.1 (95% CI, 0.01–0.69; P = 0.036) were found among cases of D. acutus envenomation compared to D. siamensis envenomation. The combination of hemorrhagic bulla, thrombocytopenia, and a lack of extremely high D-dimer had good discriminatory power (area under the curve (AUC) = 0.965; 95% CI, 0.904–1.00) for distinguishing D. acutus from D. siamensis envenomation.

Conclusions

The presentation of moderate to severe thrombocytopenia (platelet count < 100 × 10³/μL) and hemorrhagic bulla formation may indicate D. acutus envenomation. However, the envenomed patient with extremely high D-dimer levels may indicate a D. siamensis envenomation. These findings may help diagnose and select the right antivenom in patients with unknown snakebites who present significant coagulopathy.

Anti-Deinagkistrodon acutus venom properties of ethanolic root extract from Cynanchum paniculatum (Bunge) kitag and its GC-MS analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Cynanchum paniculatum (Bunge) Kitag known as a popular Chinese herbal medicine has been used for a long time to treat a wide variety of diseases including snakebites. However, there is scarce information on the antiophidian potential of this plant.

AIM OF THE STUDY

The purpose of this work was to evaluate the inhibition effects of the ethanol extract of C. paniculatum on the enzymatic and biological activities induced by Deinagkistrodon acutus venom (DAV). The phytochemical components in the extract were also determined for understanding the mechanism of antivenom activities.

MATERIALS AND METHODS

Fresh root of C. paniculatum was shed-dried and smashed into powder. The powder was then extracted in 75% ethanol by refluxing method. Inhibition of proteolytic, phospholipase A₂, fibrinogenolytic and hyaluronidase activities of DAV by the extract were determined in vitro. Neutralization of lethal, hemorrhagic, myotoxic and edematogenic activities induced by the venom were also performed in vivo. Phytochemical constituents of the extract were analyzed by gas chromatography-mass spectrometry (GC-MS).

RESULTS

The ethanolic root extract of C. paniculatum (CPER) was able to completely (100%) inhibit protease and hyaluronidase activities induced by DAV when preincubated at a ratio of 1:100 and 1:50 (venom/extract, W/W), respectively. PLA₂ and fibrinogenolytic enzyme activities were actually neutralized at the concentration tested. In-vivo studies the inhibition of venom hemorrhagic and myotoxic action reached 100% when the venom was previously incubated with the extract (1:100) before injection. The edematogenic effect was also inhibited in a dose-response manner. CPER completely inhibited DAV-induced lethality in mice when the venom was preincubated with the extract at a ratio of 1:100. GC-MS analysis indicated that a total of 58 compounds were discovered in CPER. Among them, 5 bioactive constituents including 9,12-octadecadienoic acid (Z,Z)-, n-hexadecanoic acid, cis-vaccenic acid, γ-sitosterol and stigmasterol exhibit antivenom activity according to previous reports.

CONCLUSIONS

The results obtained in this work validate for the first time CPER as a traditional antiophidic herb, especially inhibitory effect on local damage induced by DAV, suggesting it could be used as a potential source of bioactive components against snakebites.

A fatal diarrhoea outbreak in farm-raised Deinagkistrodon acutus in China is newly linked to potentially zoonotic Aeromonas hydrophila

Deinagkistrodon acutus is a venomous pit viper commonly used in traditional Chinese medicine; farming these snakes has become a major industry. In 2017, an outbreak of fatal diarrhoea among farm-raised D. acutus in Hunan Province caused the deaths of 5,600 snakes within 3 weeks. We isolated a brand-new sequence type of Aeromonas hydrophila (ST516) from lesions and confirmed that this bacterium was the causal agent of the outbreak. Snakes infected with the bacterium in the laboratory showed similar clinical symptoms to those of snakes in the original outbreak. We also tested bacterial virulence in Kunming mice to examine the likelihood of zoonosis. Isolates were pathogenic to mice, causing diarrhoea within 4 hr post-challenge, which indicates that the bacterium can potentially infect mammals. Environmental analysis showed that polluted spring water likely caused the diarrhoea in snakes. This study is the first to report on a large-scale outbreak of fatal diarrhoea in farm-raised snakes, originating in a pathogen that can infect mammals. These results should raise awareness regarding potential anthropozoonosis among poikilotherms, mammals, and humans; appropriate prevention or control methods should be developed.

Purification and Characterization of a Novel Antiplatelet Peptide from Deinagkistrodon acutus Venom

Animal venoms are considered as one of the most important sources for drug development. Deinagkistrodon acutus is famous for its toxicity to the human hematological system and envenomed patients develop a coagulation disorder with the symptoms of hemorrhage and microthrombi formation. The purpose of this study was to separate antiplatelet peptides from D. acutus venom using a combination of an ultrafiltration technique and reversed-phase high performance liquid chromatography (HPLC), which was guided by monitoring antiplatelet aggregation bioactivity. A novel octa-peptide named DAA-8 was found. This peptide inhibited protease-activated receptor1 (PAR-1) agonist (SFLLRN-NH₂) induced platelet aggregation and it also inhibited platelet aggregation induced by thrombin, ADP, and collagen. Furthermore, DAA-8 showed significant antithrombotic activity and resulted in a slightly increased bleeding risk in vivo. This is the first report of a peptide derived from snake venom, which inhibited PAR-1 agonist-induced platelet aggregation. This peptide may provide a template to design a new PAR-1 inhibitor.

Inactivation of Venom PLA₂ Alleviates Myonecrosis and Facilitates Muscle Regeneration in Envenomed Mice: A Time Course Observation

Snake venom is a complex cocktail of toxins which induces a series of clinical and pathophysiological manifestations in victims, including severe local tissue damage and systemic alterations. Deinagkistrodon acutus (D. acutus) ranks among the “big four” life-threatening venomous species in China, whose venom possesses strong myotoxicity and hematotoxicity that often lead to permanent disability or muscle atrophy. Varespladib, an inhibitor of mammalian phospholipase A₂ (PLA₂), has been recently reproposed as an effective antidote against snakebite envenomation. The present study aimed at evaluating the protective role of varespladib on muscle regeneration in envenomed mice. Mice were grouped and subjected to inoculation with D. acutus venom or a mixture of venom and varespladib or control vehicle in the gastrocnemius muscle. Local injuries including hemorrhage, myonecrosis, ulceration, and systemic damages including general dysfunction, visceral failure, and inflammatory responses were observed at 1, 3, 7, 14, and 21 days. The results indicated that most of the muscle myonecrosis and hemorrhage were alleviated by varespladib. Besides, the pretreated mice recovered rapidly with lesser atrophy and muscle fibrosis. In conclusion, the findings of the present study suggested that varespladib is an effective antidote that could neutralize D. acutus venom and allow for earlier and improved rehabilitation outcome.

Three-dimensional computed tomography reconstructive diagnosis of snakebite-induced cerebral infarction

Despite common injury caused by snakebite, snakebite-induced ischemic stroke is rare. We reported on a patient who incurred a large cerebral infarction after being bitten by a Deinagkistrodon acutus, one of the most poisonous snakes in the southwestern of China. Applying 3D computed tomography (CT) of head combined with cerebral angiography examinations showed a large cerebral infarction, hernia in the right brain, developmental abnormalities of the right middle cerebral artery and cerebral artery of right brain. In conclusion, head CT imaging combined with cerebral angiography provides an efficient approach in diagnosis of stroke caused by snakebites.

Dacin, one metalloproteinase from Deinagkistrodon acutus venom inhibiting contraction of mouse ileum muscle

Background

Mice were bitten by five-pace vipers (Deinagkistrodon acutus), and then envenomed. It was well-known that the snake venom mainly disturbed the blood homeostasis of the envenomed victims. Ocassionally, we found that the venom of D. acutus could inhibit the contraction tension of mouse ileum, so in this study we aimed to identify the active component inhibiting the contraction tension of mouse ileum in the snake venom.

Results

The active component inhibiting the contraction tension of mouse ileum, designated as Dacin, was isolated from D. acutus venom, purified to protein homogeneity and composed of a single peptide chain, about 23 kDa analyzed by SDS-PAGE, and 22, 947. 9 Da measured by MALDI-TOF-MS. Not only the results of its PMF blasted by Mascot indicated that Dacin may be one snake venom metalloproteinase (SVMP), but also the results of the biochemical and in-vivo assays as follow demonstrated that it was one SVMP: it cleaved Aα and Bβ chains, not Cγ of bovine fibrinogen within 1 h, and also hydrolyzed fibrin polymer; besides its fibrino(geno)lytic activities were strongly inhibited by β- mercaptoethanol, EDTA and EGTA; and it could induce a hemorrhagic reaction under the dorsal skin of mouse. In the isolated tissue assays, Dacin caused the concentration-dependent and time-dependent inhibitory actions on the spontaneous contraction tension of the ileum smooth muscle of mouse, and the inhibitory effects were irreversible.

Conclusions

Taken together, for the first time one active component (Dacin, a SVMP) that irreversibly inhibited the spontaneous contraction tension of mouse ileum has been isolated and identified from D. acutus venom. The findings may provide not only a new insight for toxicological researches on SVMPs and venoms of the vipers, but also a reference for clinicians to treat the snake-bitten victims. However, Dacin’s inhibitory molecular mechanism will be further studied in the future.

Preparation and neutralization efficacy of IgY antibodies raised against Deinagkistrodon acutus venom

Background

The five-paced pit viper (Deinagkistrodon acutus), endemic to China and northern Vietnam, is responsible for most snakebites in the Chinese territory. Antivenom produced from horses is the main treatment for snakebites, but it may cause numerous clinical side effects and have other disadvantages involved in their production such as the welfare of animals. The present study was conducted aiming to develop an alternative antibody (IgY) from the egg yolk of leghorn chickens immunized with snake venom.

Methods

IgY from the egg yolk of white leghorn chickens previously immunized intramuscularly with D. acutus venom was extracted by water, precipitated by ammonium sulfate and purified by affinity chromatographic system. IgY was identified by SDS-PAGE, ELISA and Western blot. Finally, IgY neutralization assays to test its efficacy against hemorrhagic, edema-forming and myotoxic activities of D. acutus venom were conducted on mice.

Results

For the first time, IgY antibodies against D. acutus venom were raised successfully in egg yolk of chickens injected with D. acutus venom multiple times. By three steps, including caprylic acid extraction, ammonium sulfate precipitation and affinity chromatography, IgY antibodies were isolated and purified from egg yolk, which exhibited a single protein band on SDS-PAGE and two bands (about 65 kDa and 35 kDa, respectively) under reducing conditions, and presented a high titer (1:40,000) tested by ELISA. Immunoblot analysis confirmed that these IgY were polyclonal antibodies since they bound to components of D. acutus venom. Furthermore, immunodiffusion assay showed that anti-D. acutus venom IgY cross-reacted with the venoms of Trimeresurus albolabris and D. saxatilis Emelianov, but did not react to the venoms of Bungarus multicinctus and Naja atra. In the neutralizing lethal assay, the median effective dose of anti-D. acutus venom IgY was 14.14 mg/kg of mouse body weight under the challenge dose (3 LD₅₀ of D. acutus venom). In neutralizing the hemorrhagic, edema-forming and myotoxic activities of D. acutus venom, IgY showed the characteristic dose-dependent neutralization effects against all these toxic activities of D. acutus venom.

Conclusion

Anti-D. acutus venom IgY antibodies with high purity and titer were for the first time raised successfully in egg yolk of chickens immunized with D. acutus venom. They were effective in neutralizing the lethal effects, and the hemorrhagic, edema-forming and myotoxic acitivities of D. acutus venom. IgY could be an effective source to develop a treatment against snake bites in humans or animals in the future.

Deinagkistrodon acutus envenomation: a report of three cases

Background

Deinagkistrodon acutus envenomation is associated with severe hematological and wound complications but is rarely described.

Case presentation

Herein, we report three cases of victims bitten by D. acutus and indicate that rapid-onset severe coagulopathy and thrombocytopenia are distinct features of D. acutus snakebite, which are not observed in other crotaline snakebites (i.e., Trimeresurus stejnegeri and Protobothrops mucrosquamatus) in Taiwan. The toxic effects could occur as early as 2 to 3 h following D. acutus envenomation and persist if the administration of specific antivenom is delayed or even not commenced. Based on our findings, 2 to 4 vials of specific antivenom as the first dose should be administered to victims and repeated at 6 to 8 h intervals if coagulopathy or thrombocytopenia persists. Fresh frozen plasma or platelet replacement is probably safe as an adjunct therapy for D. acutus bite in the presence of venom-induced consumptive coagulopathy.

Conclusion

Severe coagulopathy and thrombocytopenia could occur as early as 2 to 3 h after D. acutus envenomation. The current recommendation for antivenom is 2 to 4 vials as the first dose and repeated every 6– to 8 h if coagulopathy or thrombocytopenia persists. These cases studied may be helpful to first-line medical personnel in the early diagnosis and management of D. acutus envenomation among other crotaline snakebites in Taiwan.

Screening, tandem expression and immune activity appraisal of Deinagkistrodon acutus (pit viper) venom mimotopes from a phage display 12-mer peptide library

OBJECTIVE

To design a specific polyclonal antibody against Deinagkistrodon acutus venom (DA-pAb) by immunizating New Zealand white rabbits.

RESULTS

The IgG fraction was purified by affinity chromatography, and specific antibodies were purified by immunoaffinity chromatography. Polyclonal antibodies were subjected to ELISA and western blotting to evaluate their immune reactivity. We identified the mimotopes by screening a phage display 12-mer peptide library against D. acutus venom. After three rounds of biopanning with DA-pAb, 30 positive clones were identified. Eighteen phage clones were sequenced, and their corresponding amino acid sequences were deduced. Additional immunoassays with the peptides and DA-pAb identified five sequences as possible epitopes. Recombinant antigens synthesized with the five epitopes were used for the immunization of BALB/c mice.

CONCLUSION

The antibodies induced by these peptides recognized the recombinant antigen and D. acutus venom and protected mice against the hemorrhagic effects of the venom.

Purification and Immunoprotection Evaluation of AaHIV from Complex Venom Metalloproteinases of Deinagkistrodon acutus

The aim of this study was to investigate the immunoprotective effects of AaHIV in mice. After purification, a 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed. Bicinchoninic acid was used to determine the molecular weight and concentration of AaHIV. AaHIV, venom complex (VC), and phosphate buffered saline (PBS) were subsequently used to immunize the mice three times, and the blood was sampled 1 week after the third immunization to determine the serum immunoglobulin G (IgG) antibody titer. A skin-bleeding inhibition assay and toxin-eliminating assay were performed on the immunized mice. The purity and concentration of AaHIV were 86.6% and 1.20 mg/mL, respectively. The AaHIV group exhibited higher antibody titers than the VC group. The survival rate of the AaHIV group (7/10) was significantly higher than that of the PBS group (0/10) (P = 0.0031). The high titer of antibodies induced by AaHIV partially neutralized the bleeding activity of the Deinagkistrodon acutus venom complex.

Purification and partial characterization of a novel fibrinogenase from the venom of Deinagkistrodon acutus: inhibition of platelet aggregation

A novel fibrinogenase, DAnase, was purified from the venom of Deinagkistrodon acutus by a combination of anion and cation exchange chromatography. Unlike other fibrinogenases which are usually single polypeptide chain proteins, the enzyme was a disulfide-linked dimer with an isoelectric point of 6.03 and an apparent molecular weight of 25kDa on SDS-polyacrylamide gel electrophoresis. DAnase showed α-fibrinogenase activity devoid of fibrinolytic activity. It hydrolyzed rapidly the Aα-chain of fibrinogen and followed by the Bβ-chain and did not cleave the γ-chain. It also exhibited arginine esterase activity. The fibrinogenolytic and arginine esterase activities were completely inhibited by phenylmethanesulfonyl fluoride or tris-(2-carboxyethyl)phosphine hydrochloride, but not by EDTA, indicating that DAnase is a serine protease requiring disulfide bridge(s) for its activity. The protease strongly inhibited ADP-induced platelet aggregation in human platelet-rich plasma but was lack of ADPase activity, indicating that its fibrinogenolytic activity is involved in its inhibition of ADP-induced platelet aggregation. DAnase was devoid of hemorrhagic activity and Factor XIII activation activity. DAnase may have a potential clinical application for the therapy of thrombosis disease.