The action of various venoms on Escherichia coli

The antibacterial activity of honeybee venom ( Apis mellifera ), three snake venoms ( Naja naja sputatrix, Vipera russellii and Crotalus adamanteus ) and the polypeptide melittin was investigated against Escherichia coli . Minimum inhibitory concentration values, cell lysis and alterations in cell permeability were determined and action against E. coli was in the order: A. mellifera venom > melittin > N. naja sputatrix venom ≫ V. russellii venom > C. adamanteus venom. Cellular damage by A. mellifera and N. naja sputatrix venoms was evident in electron micrographs.     

The action of various venoms on Escherichia coli

The antibacterial activity of honeybee venom (Apis mellifera), three snake venoms (Naja naja sputatrix, Vipera russellii and Crotalus adamanteus) and the polypeptide melittin was investigated against Escherichia coli. Minimum inhibitory concentration values, cell lysis and alterations in cell permeability were determined and action against E. coli was in the order: A. mellifera venom greater than melittin greater than N. naja sputatrix venom much greater than V. russellii venom greater than C. adamanteus venom. Cellular damage by A. mellifera and N. naja sputatrix venoms was evident in electron micrographs.     

The anticoagulant activity of Malayan cobra (Naja naja sputatrix) venom and venom phospholipase A2 enzymes

Malayan cobra (Naja naja sputatrix) venom was found to exhibit an in vitro anticoagulant activity that was much stronger than most common cobra (genus Naja) venoms. The most potent anticoagulants of the venom are two lethal phospholipase A2 enzymes with pI's of 6.15 and 6.20, respectively. The anticoagulant activity of the venom is due to the synergistic effect of the venom phospholipase A2 enzymes and polypeptide anticoagulants. Bromophenacylation of the two phospholipase A2 enzymes reduced their enzymatic activity with a concomitant drop in both the lethal and anticoagulant activities.     

Isolation and characterization of an acidic lethal phospholipase Az from Malayan cobra (Naja naja sputatrix) venom

An acidic, lethal phospholipase Az was purified to electrophoretic homogeneity from the venom of the Malayan cobra (Naja naja sputatrix). The enzyme has an isoelectric point of 5.58, a molecular weight of 12000, and a medium lethal dose (LD50) of 0.86 micrograms/g in mice by intravenous injection. The enzyme also exhibited weak anticoagulant and edema-forming activities. The amino acid composition of the enzyme is similar to those of other cobra venom phospholipases Az.     

Proteomic analysis of the pathophysiological process involved in the antisnake venom effect of Mucuna pruriens extract

Previously, we reported the antisnake venom properties of a Mucuna pruriens seed extract (MPE) and tested its in vivo efficacy against Echis carinatus venom (EV) in short- (1 injection) and long-term (three weekly injections) treatments. The aim of the present study was to investigate plasma proteome changes associated with MPE treatments and identify proteins responsible for survival of envenomated mice (CHALLENGED mice). Six treatment groups were studied. Three control groups: one saline, one short-term and one long-term MPE treatment. One group received EV alone. Two test groups received EV with either a short-term or long-term MPE treatment (CHALLENGED mice). The plasma from each group was analysed by 2-DE/MALDI-TOF MS. The most significant changes with treatment were: albumin, haptoglobin, fibrinogen, serum amyloid A and serum amyloid P. Most of these changes were explained by EV effects on coagulation, inflammation and haemolysis. However, MPE treatments prevented the EV-induced elevation in HPT. Consequently, HPT levels were similar to controls in the plasma of CHALLENGED mice. The plasma of CHALLENGED mice showed substantial proteomic modifications. This suggests the mechanism of MPE protection involves the activation of counterbalancing processes to compensate for the imbalances caused by EV.     

Alpha-neurotoxin gene expression in Naja sputatrix: identification of a silencer element in the promoter region

Alpha-neurotoxin (alpha-NTX) from the venom of cobra, Naja sputatrix, is a highly lethal post-synaptic toxin that is responsible for the lethality caused by the venom. However, this toxin is found at low levels (3%) in the crude venom. The expression of its gene is determined by a promoter which is 90% similar to the promoter of another three-fingered toxin, cardiotoxin (CTX), which is produced in large amounts (60%) in the same venom. Functional analysis of the NTX-2 gene promoter demonstrated the presence of a silencer element of 24 nucleotides (nt -678 to -655) at its 5(') flanking region. This element has been found to play a major role in the down-regulation of NTX-2 gene expression. A point mutation on this silencer appears to attenuate its repressive property in CTX-2 gene.     

Proteins from Mucuna pruriens and enzymes from Echis carinatus venom: characterization and cross-reactions

Mucuna pruriens seeds have been widely used against snakebite in traditional medicine. The antivenin property of a water extract of seeds was assessed in vivo in mice. The serum of mice treated with extract was tested for its immunological properties. Two proteins of Echis carinatus venom with apparent molecular masses of 25 and 16 kDa were detected by Western blot analysis carried out using IgG of mice immunized with extract or its partially purified protein fractions. By enzymatic in-gel digestion and electrospray ionization-mass spectrometry/mass spectrometry analysis of immunoreactive venom proteins, phospholipase A(2,) the most toxic enzyme of snake venom, was identified. These results demonstrate that the observed antivenin activity has an immune mechanism. Antibodies of mice treated with non-lethal doses of venom reacted against some proteins of M. pruriens extract. Proteins of E. carinatus venom and M. pruriens extract have at least one epitope in common as confirmed by immunodiffusion assay.     

Antibacterial action of a heat-stable form of L-amino acid oxidase isolated from king cobra (Ophiophagus hannah) venom

The major l-amino acid oxidase (LAAO, EC 1.4.3.2) of king cobra (Ophiophagus hannah) venom is known to be an unusual form of snake venom LAAO as it possesses unique structural features and unusual thermal stability. The antibacterial effects of king cobra venom LAAO were tested against several strains of clinical isolates including Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli using broth microdilution assay. For comparison, the antibacterial effects of several antibiotics (cefotaxime, kanamycin, tetracycline, vancomycin and penicillin) were also examined using the same conditions. King cobra venom LAAO was very effective in inhibiting the two Gram-positive bacteria (S. aureus and S. epidermidis) tested, with minimum inhibitory concentration (MIC) of 0.78μg/mL (0.006μM) and 1.56μg/mL (0.012μM) against S. aureus and S. epidermidis, respectively. The MICs are comparable to the MICs of the antibiotics tested, on a weight basis. However, the LAAO was only moderately effective against three Gram-negative bacteria tested (P. aeruginosa, K. pneumoniae and E. coli), with MIC ranges from 25 to 50μg/mL (0.2-0.4μM). Catalase at the concentration of 1mg/mL abolished the antibacterial effect of LAAO, indicating that the antibacterial effect of the enzyme involves generation of hydrogen peroxide. Binding studies indicated that king cobra venom LAAO binds strongly to the Gram-positive S. aureus and S. epidermidis, but less strongly to the Gram-negative E. coli and P. aeruginosa, indicating that specific binding to bacteria is important for the potent antibacterial activity of the enzyme.     

Cobra venom contains a pool of cysteine-rich secretory proteins

A large family of cysteine-rich secretory proteins (CRISPs) includes proteins of different origin, the function of the majority of CRISPs being unknown. For CRISPs isolated from snake venom, two types of activities were found: two proteins blocked cyclic nucleotide-gated ion channels, several others blocked potassium-stimulated smooth muscle contraction. Thus, snake CRISPs represent potentially valuable tools for studies of ion channels, which makes promising a search for new CRISPs. Here we report on the isolation of several novel CRISPs from the venoms of Asian cobra Naja kaouthia and African cobra Naja haje using a combination of different types of liquid chromatography. Four CRISP variants were identified in N. kaouthia venom and three proteins, one of them acidic, were found in N. haje venom. Acidic CRISP was found in a reptilian venom for the first time. Our data suggest that each cobra venom contains a pool of different CRISPs.     

Activation, aggregation, and product inhibition of cobra venom phospholipase A2 and comparison with other phospholipases

The kinetics of phospholipid hydrolysis by cobra venom phospholipase A2 were examined and compared to those of phospholipase A2 from porcine pancreas, Crotalus adamanteus (rattlesnake) venom, and bee venom. Only the enzyme from Naja naja naja (cobra) venom was found to be activated significantly by phosphorylcholine-containing compounds when hydrolyzing phosphatidylethanolamine. The cobra venom enzyme was also the only one in which these activators induced protein aggregation. The parallel specificity for activators and aggregators suggests that these two phenomena are linked. Product effects were also shown to vary between these four phospholipases. These effects manifest themselves in nonlinear time courses, in changes in steady state velocity, and in the differential effects of serum albumin on reaction rates. Different effects were even seen for the same enzyme when acting on different substrates. A model is presented to account for these observations; its main features are enzyme activation by an activator molecule, whose specificity depends on the enzyme, and an activator-induced aggregation of the enzyme.     

Antibacterial activity of cardiotoxin-like basic polypeptide from cobra venom

Antibacterial activity of the three-finger toxins from cobra venom, including cytotoxin 3 from N. kaouthia, cardiotoxin-like basic polypeptide A5 from N. naja (CLBP), and alpha-neurotoxin from N. oxiana venom, was investigated. All toxins failed to influence Gram-negative bacteria. The most pronounced activity against Bacillus subtilis was demonstrated by CLBP. The latter is ascribed to the presence of additional Lys-residues within the membrane-binding motif of this toxin.     

Muscarinic acetylcholine receptor (mAChR) inhibitor from snake venom: interaction with subtypes of human mAChR.

Snake venoms can contain a variety of well-studied neurotoxins, especially nicotinic acetylcholine receptor inhibitor, normally called postsynaptic neurotoxin. Karlsson first reported muscarinic acetylcholine receptor (mAChR) inhibitor from snake venom. In a previous study in our laboratory, we found a mAChR inhibitor from Naja naja sputatrix venom that bound to rat brain synaptosomes. Brain synaptosomes contain all subtypes of mAChRs, and thus the exact selectivity of the inhibitor could not be determined. mAChR inhibitor from N. naja sputatrix venom was purified and the binding to all human mAChR subtypes (M1, M2, M3, M4, and M5) was investigated and is reported in this communication. The inhibitor bound to all subtypes of the human mAChR, but showed considerably high selectivity for the M5 subtype. It was also found that the reduction of disulfide bonds in the inhibitor eliminated the binding to the mAChR. This suggests that a specific tertiary conformation maintained by disulfide bonds is essential for binding to the mAChR. An oligo peptide, QIHDNCYNE, comparable to a part of the inhibitor molecule, was synthesized and studied for its binding to the mAChR. The synthetic peptide did not show any binding activity, suggesting this portion of the inhibitor molecule is not involved in mAChR binding. The selective binding of the M5 mAChR subtype to antagonists has not yet been reported. Therefore, the purified inhibitor reported in this communication may be a useful tool to clarify the mechanism of muscarinic cholinergic transmission.     

Proteomics analysis to compare the venom composition between Naja naja and Naja kaouthia from the same geographical location of eastern India: Correlation with pathophysiology of envenomation and immunological cross-reactivity towards commercial polyantivenom

ABSTRACT

Background : Cobra bite is frequently reported across the Indian subcontinent and is associated with a high rate of death and morbidity. In eastern India (EI) Naja naja and Naja kaouthia are reported to be the two most abundant species of cobra.

Research design and methods : The venom proteome composition of N. naja (NnV) and N. kaouthia (NkV) from Burdwan districts of EI were compared by separation of venom proteins by 1D-SDS-PAGE followed by LC-MS/MS analysis of protein bands. The potency of commercial polyantivenom (PAV) was assessed by neutralization, ELISA, immuno-blot and venom-PAV immunoaffinity chromatography studies.

Results : Proteomic analysis identified 52 and 55 proteins for NnV and NkV, respectively, when searched against the Elapidae database. A small quantitative difference in venom composition between these two species of cobra was observed. PAVs exhibited poor cross-reactivity against low molecular mass toxins (<20 kDa) of both cobra venoms, which was substantiated by a meager neutralization of their phospholipase A₂ activity. Phospholipase A₂ and 3FTx, the two major classes of nonenzymatic and enzymatic proteins, respectively, were partially recognized by PAVs.

Conclusions : Efforts must be made to improve immunization protocols and supplement existing antivenoms with antibodies raised against the major toxins of these venoms.     

Identifying Intraspecific Variation in Venom Yield of Chinese Cobra(Naja atra) from Ten Populations in Mainland China

Detailed information on venom yield is helpful in preparing antivenoms and treating snakebites, but such information is lacking for many species of venomous snakes. The Chinese cobra(Naja atra) is a large sized, venomous snake commonly found in southeastern China, where it causes a heavy burden of snakebites. To examine the effects of various factors(morphology, sex, age, season, and geographical origin) on the venom yield in this snake, we collected venom samples of 446 individuals(426 adults and 20 neonates) from 10 populations of N. atra over an eightyear period. We used two variables, lyophilized venom mass(venom yield) and solid content of venom(% solids), to quantify the venom yield. We used linear regression analysis to check if venom yield was related to morphological factors, one-way ANOVA and one-way ANCOVA to detect the sexual, ontogenetic, and geographic variation in venom yield, and repeated-measures ANOVA to examine seasonal shifts in venom yield. Our results indicate that venom yield of N. atra is positively related to the morphological traits examined, with male snakes expelling more venom than females. Venom yield in N. atra was age-related, with elder snakes always expelling more venom than younger ones. Geographic variation in venom yield was also observed, while seasonal variation was not. The solid content of venom was lower in males than in females, but this was not related to morphology, season, age, or geography. Our findings suggest that venom yield in N. atra is influenced by multiple factors, as well as by the interactions among these factors.     

Production of potent antivenin against cobra venom with conjugated-cobrotoxin.

Cobra venom (Naja naja atra) and its fractions obtained by ammonium sulfate precipitation were subjected to chromatography on CM-Cellulose colum. A highly purified cobrotoxin obtained by the repeated chromatography on preparative CM-Cellulose column was 6.7 times more toxic than the original cobra venom. The toxin was detoxified by a bifunctional reagent, glutaraldehyde, to about 99.8% and utilized for immunization in animals. Mice received 4 weekly immunization with detoxified cobrotoxin and challenged one week after the last injection showed 60% protection in rabbits by immunization with detoxified cobrotoxin reached 360 LD50 neutralizing level against the cobra venom within 30 days. The results indicate that it is feasible and promising to prepare potent antivenin in animals by glutaraldehyde-treated cobrotoxin.     

Neutralization of cobra venom by cocktail antiserum against venom proteins of cobra (Naja naja naja)

Naja naja venom was characterized by its immunochemical properties and electrophoretic pattern which revealed eight protein bands (14 kDa, 24 kDa, 29 kDa, 45 kDa, 48 kDa, 65 kDa, 72 kDa and 99 kDa) by SDS-PAGE in reducing condition after staining with Coomassie Brilliant Blue. The results showed that Naja venom presented high lethal activity. Whole venom antiserum or individual venom protein antiserum (14 kDa, 29 kDa, 65 kDa, 72 kDa and 99 kDa) of venom could recognize N. naja venom by Western blotting and ELISA, and N. naja venom presented antibody titer when assayed by ELISA. The neutralization tests showed that the polyvalent antiserum neutralized lethal activities by both in vivo and in vitro studies using mice and Vero cells. The antiserum could neutralize the lethal activities in in-vivo and antivenom administered after injection of cobra venom through intraperitoneal route in mice. The cocktail antiserum also could neutralize the cytotoxic activities in Vero cell line by MTT and Neutral red assays. The results of the present study suggest that cocktail antiserum neutralizes the lethal activities in both in vitro and in vivo models using the antiserum against cobra venom and its individual venom proteins serum produced in rabbits.     

乙醇对中华眼镜蛇毒毒性的影响

目的为了探索乙醇对眼镜蛇毒毒性的影响。方法将眼镜蛇毒不同浓度致死量经不同浓度乙醇体外处理后,分别于小白鼠皮下注射、口服,将致死量蛇毒皮下注射后的小白鼠立即于局部注射乙醇,观察蛇毒毒性情况。结果小白鼠经皮下注射致死量眼镜蛇毒后,在局部注射50％（或异蛇米酒）、75％乙醇0．1～0．2ml有一定的保护作用;口服100倍皮下注射致死量眼镜蛇毒未发现有毒性表现,口服经50％乙醇处理后的眼镜蛇毒（100倍皮下注射致死量）未增加小鼠死亡率。结论眼镜蛇毒体外经过乙醇处理后毒性有所下降。口服少量的眼镜蛇毒是安全的。眼镜蛇毒与乙醇混合后口服未见蛇毒毒性增加。     

抗蛇毒血清滴眼治疗眼镜蛇毒致眼外伤

目的观察单价抗眼镜蛇毒血清溶液滴眼治疗中华眼镜蛇毒(Naja naja atra,Chinese cobra)不慎进人眼睛引起外伤中毒性急性角膜炎的临床效果。方法观察1992～2002年我院急诊救治眼镜蛇喷毒或加工蛇毒时不慎蛇毒进人眼睛引起外伤性急性角膜炎8例男性病人,从受伤到就诊时间最快15min,最慢50min。就诊后立即用生理盐水冲洗受伤眼睛,紧接着给予单价抗眼镜蛇毒血清溶液滴人患眼0．5h后,用氯霉素眼药水、可的松(或地塞米松)眼药水交替滴眼,直至痊愈。结果使用抗蛇毒血清滴眼后局部疼痛、异物感等症状在20min内得到缓解,3天内眼睑红肿、结膜充血等角膜炎症状消失。8例病人均治愈,未留有后遗症。结论：单价抗眼镜蛇毒血清滴眼治疗中华眼镜蛇毒致眼外伤是非常方便有效的方法,可能与其能迅速中和眼睛内残留的蛇毒有关。