Novel sequences encoding venom C-type lectins are conserved in phylogenetically and geographically distinct Echis and Bitis viper species

Signature selection forces and evolutionary divergence of immune-survival genes compared between two important shrimp species

In recent years, shrimp aquaculture industry had grown significantly to become the major source of global shrimp production. Despite that, shrimp aquaculture production was impeded by various shrimp diseases over the past decades. Interestingly, different shrimp species demonstrated variable levels of immune strength and survival (immune-survival) ability towards different diseases, especially the much stronger immune-survival ability shown by the ancient shrimp species, Macrobrachium rosenbergii compared to other shrimp species. In this study, two important shrimp species, M. rosenbergii and Penaeus monodon (disease tolerant strain) (uninfected control and VpAHPND-infected) were compared to uncover the potential underlying genetic factors. The shrimp species were sampled, followed by RNA extraction and cDNA conversion. Five important immune-survival genes (C-type Lectin, HMGB, STAT, ALF3, and ATPase 8/6) were selected for PCR, sequencing, and subsequent genetics analysis. The overall genetic analyses conducted, including Analysis of Molecular Variance (AMOVA) and population differentiation, showed significant genetic differentiation (p<0.05) between different genes of M. rosenbergii and P. monodon. There was greater genetic divergence identified between HMGB subgroups of P. monodon (uninfected control and VpAHPND-infected) compared to other genes. Besides that, based on neutrality tests conducted, purifying selection was determined to be the main evolutionary driving force of M. rosenbergii and P. monodon with stronger purifying selection exhibited in M. rosenbergii genes. Potential balancing selection was identified for VpAHPND-infected HMGB subgroup whereas directional selection was detected for HMGB (both species) and ATPase 8/6 (only P. monodon) genes. The divergence times between M. rosenbergii and P. monodon genes were estimated through Bayesian molecular clock analysis, which were 438.6 mya (C-type Lectin), 1885.4 mya (HMGB), 432.6 mya (STAT), 448.1 mya (ALF3), and 426.4 mya (ATPase 8/6) respectively. In conclusion, important selection forces and evolutionary divergence information of immune-survival genes between M. rosenbergii and P. monodon were successfully identified.

Camels' biological fluids contained nanobodies: promising avenue in cancer therapy

Cancer is a major health concern and accounts for one of the main causes of death worldwide. Innovative strategies are needed to aid in the diagnosis and treatment of different types of cancers. Recently, there has been an evolving interest in utilizing nanobodies of camel origin as therapeutic tools against cancer. Nanotechnology uses nanobodies an emerging attractive field that provides promises to researchers in advancing different scientific sectors including medicine and oncology. Nanobodies are characteristically small-sized biologics featured with the ability for deep tissue penetration and dissemination and harbour high stability at high pH and temperatures. The current review highlights the potential use of nanobodies that are naturally secreted in camels’ biological fluids, both milk and urine, in the development of nanotechnology-based therapy for treating different typesQuery of cancers and other diseases. Moreover, the role of nano proteomics in the invention of novel therapeutic agents specifically used for cancer intervention is also illustrated.

Bitiscetin-3, a Novel C-Type Lectin-like Protein Cloned from the Venom Gland of the Viper Bitis arietans, Induces Platelet Agglutination and Inhibits Binding of Von Willebrand Factor to Collagen

Bitiscetin-1 (aka bitiscetin) and bitiscetin-2 are C-type lectin-like proteins purified from the venom of Bitis arietans (puff adder). They bind to von Willebrand factor (VWF) and—at least bitiscetin-1—induce platelet agglutination via enhancement of VWF binding to platelet glycoprotein Ib (GPIb). Bitiscetin-1 and -2 bind the VWF A1 and A3 domains, respectively. The A3 domain includes the major site of VWF for binding collagen, explaining why bitiscetin-2 blocks VWF-to-collagen binding. In the present study, sequences for a novel bitiscetin protein—bitiscetin-3—were identified in cDNA constructed from the B. arietans venom gland. The deduced amino acid sequences of bitiscetin-3 subunits α and β share 79 and 80% identity with those of bitiscetin-1, respectively. Expression vectors for bitiscetin-3α and -3β were co-transfected to 293T cells, producing the heterodimer protein recombinant bitiscetin-3 (rBit-3). Functionally, purified rBit-3 (1) induced platelet agglutination involving VWF and GPIb, (2) did not compete with bitiscetin-1 for binding to VWF, (3) blocked VWF-to-collagen binding, and (4) lost its platelet agglutination inducing ability in the presence of an anti-VWF monoclonal antibody that blocked VWF-to-collagen binding. These combined results suggest that bitiscetin-3 binds to the A3 domain, as does bitiscetin-2. Except for a small N-terminal fragment of a single subunit—which differs from that of both bitiscetin-3 subunits—the sequences of bitiscetin-2 have never been determined. Therefore, by identifying and analyzing bitiscetin-3, the present study is the first to present the full-length α- and β-subunit sequences and recombinant expression of a bitiscetin-family toxin that blocks the binding of VWF to collagen.

High throughput screening and identification of coagulopathic snake venom proteins and peptides using nanofractionation and proteomics approaches

Snakebite is a neglected tropical disease that results in a variety of systemic and local pathologies in envenomed victims and is responsible for around 138,000 deaths every year. Many snake venoms cause severe coagulopathy that makes victims vulnerable to suffering life-threating haemorrhage. The mechanisms of action of coagulopathic snake venom toxins are diverse and can result in both anticoagulant and procoagulant effects. However, because snake venoms consist of a mixture of numerous protein and peptide components, high throughput characterizations of specific target bioactives is challenging. In this study, we applied a combination of analytical and pharmacological methods to identify snake venom toxins from a wide diversity of snake species that perturb coagulation. To do so, we used a high-throughput screening approach consisting of a miniaturised plasma coagulation assay in combination with a venom nanofractionation approach. Twenty snake venoms were first separated using reversed-phase liquid chromatography, and a post-column split allowed a small fraction to be analyzed with mass spectrometry, while the larger fraction was collected and dispensed onto 384-well plates. After fraction collection, any solvent present in the wells was removed by means of freeze-drying, after which it was possible to perform a plasma coagulation assay in order to detect coagulopathic activity. Our results demonstrate that many snake venoms simultaneously contain both procoagulant and anticoagulant bioactives that contribute to coagulopathy. In-depth identification analysis from seven medically-important venoms, via mass spectrometry and nanoLC-MS/MS, revealed that phospholipase A2 toxins are frequently identified in anticoagulant venom fractions, while serine protease and metalloproteinase toxins are often associated with procoagulant bioactivities. The nanofractionation and proteomics approach applied herein seems likely to be a valuable tool for the rational development of next-generation snakebite treatments by facilitating the rapid identification and fractionation of coagulopathic toxins, thereby enabling specific targeting of these toxins by new therapeutics such as monoclonal antibodies and small molecule inhibitors.

Anticancer Activity of Camel Milk via Induction of Autophagic Death in Human Colorectal and Breast Cancer Cells

Background/Objective:

Camel milk is traditionally known for its human health benefits and believed to be a remedy for various human ailments including cancer. The study was aimed to evaluate the inhibitory effects of commercially available camel milk on cancer cells and its underlying mechanism(s).

Materials and Methods:

Two cell lines: colorectal cancer HCT 116 and breast cancer MCF-7 were cultured with different doses of camel milk. The effects of camel milk on cell death were determined by MTT assay, viability by trypan blue exclusion assay and migration by in vitro scratch assay. The mechanism was elucidated by western blotting and confocal microscopy was used to confirm autophagy.

Results:

Camel milk significantly reduced proliferation, viability as well as migration of both the cells. The accumulation of LC3-II protein along with reduction in expression of p62 and Atg 5-12, the autophagy proteins implied induction of autophagy. The (GFP)-LC3 puncta detected by confocal microscopy confirmed the autophagosome formation in response to camel milk treatment.

Conclusion:

Camel milk exerted antiproliferative effects on human colorectal HCT 116 and breast MCF-7 cancer cells by inducing autophagy.

In Vitro Apoptosis Triggering in the BT-474 Human Breast Cancer Cell Line by Lyophilised Camel's Milk

Breast cancer is a global health concern and is a major cause of death among women. In Oman, it is the most common cancer in women, with an incidence rate of 15.6 per 100,000 Omani females. Various anticancer remedies have been discovered from natural products in the past and the search is continuing for additional examples. Cytotoxic natural compounds may have a major role in cancer therapy either in potentiating the effect of chemotherapy or reducing its harmful effects. Recently, a few studies have reported advantages of using crude camel milk in treating some forms of cancer. However, no adequate data are available on the lyophilised camel's milk responsibility for triggering apoptosis and oxidative stress associated with human breast cancer. The present study aimed to address the role of the lyophilised camel's milk in inducing proliferation repression of BT-474 and HEp-2 cells compared with the non-cancer HCC1937 BL cell line. Lyophilized camel's milk fundamentally repressed BT-474 cells growth and proliferation through the initiation of either the intrinsic and extrinsic apoptotic pathways as indicated by both caspase-3 mRNA and its action level, and induction of death receptors in BT-474 but not the HEp-2 cell line. In addition, lyophilised camel's milk enhanced the expression of oxidative stress markers, heme-oxygenase-1 and reactive oxygen species production in BT-474 cells. Increase in caspase-3 mRNA levels by the lyophilised camel's milk was completely prevented by the actinomycin D, a transcriptional inhibitor. This suggests that lyophilized camel's milk increased newly synthesized RNA. Interestingly,it significantly (p<0.003) repressed the growth of HEp-2 cells and BT-474 cells after treatment for 72 hours while 24 hours treatment repressed BT-474 cells alone. This finding suggests that the lyophilised camel's milk might instigate apoptosis through initiation of an alternative apoptotic pathway.

Lebecin, a new C-type lectin like protein from Macrovipera lebetina venom with anti-tumor activity against the breast cancer cell line MDA-MB231

C-type lectins like proteins display various biological activities and are known to affect especially platelet aggregation. Few of them have been reported to have anti-tumor effects. In this study, we have identified and characterized a new C-type lectin like protein, named lebecin. Lebecin is a heterodimeric protein of 30 kDa. The N-terminal amino acid sequences of both subunits were determined by Edman degradation and the entire amino acid sequences were deduced from cDNAs. The precursors of both lebecin subunits contain a 23-amino acid residue signal peptide and the mature α and β subunits are composed of 129 and 131 amino acids, respectively. Lebecin is shown to be a potent inhibitor of MDA-MB231 human breast cancer cells proliferation. Furthermore, lebecin dose-dependently inhibited the integrin-mediated attachment of these cells to different adhesion substrata. This novel C-type lectin also completely blocked MDA-MB231 cells migration towards fibronectin and fibrinogen in haptotaxis assays.

Rhinocetin, a venom-derived integrin-specific antagonist inhibits collagen-induced platelet and endothelial cell functions

Snaclecs are small non-enzymatic proteins present in viper venoms reported to modulate hemostasis of victims through effects on platelets, vascular endothelial, and smooth muscle cells. In this study, we have isolated and functionally characterized a snaclec that we named "rhinocetin" from the venom of West African gaboon viper, Bitis gabonica rhinoceros. Rhinocetin was shown to comprise α and β chains with the molecular masses of 13.5 and 13 kDa, respectively. Sequence and immunoblot analysis of rhinocetin confirmed this to be a novel snaclec. Rhinocetin inhibited collagen-stimulated activation of human platelets in a dose-dependent manner but displayed no inhibitory effects on glycoprotein VI (collagen receptor) selective agonist, CRP-XL-, ADP-, or thrombin-induced platelet activation. Rhinocetin antagonized the binding of monoclonal antibodies against the α2 subunit of integrin α2β1 to platelets and coimmunoprecipitation analysis confirmed integrin α2β1 as a target for this venom protein. Rhinocetin inhibited a range of collagen-induced platelet functions such as fibrinogen binding, calcium mobilization, granule secretion, aggregation, and thrombus formation. It also inhibited integrin α2β1-dependent functions of human endothelial cells. Together, our data suggest rhinocetin to be a modulator of integrin α2β1 function and thus may provide valuable insights into the role of this integrin in physiological and pathophysiological scenarios, including hemostasis, thrombosis, and envenomation.

Serine protease variants encoded by Echis ocellatus venom gland cDNA: cloning and sequencing analysis

Envenoming by Echis saw-scaled viper is the leading cause of death and morbidity in Africa due to snake bite. Despite its medical importance, there have been few investigations into the toxin composition of the venom of this viper. Here, we report the cloning of cDNA sequences encoding four groups or isoforms of the haemostasis-disruptive Serine protease proteins (SPs) from the venom glands of Echis ocellatus. All these SP sequences encoded the cysteine residues scaffold that form the 6-disulphide bonds responsible for the characteristic tertiary structure of venom serine proteases. All the Echis ocellatus EoSP groups showed varying degrees of sequence similarity to published viper venom SPs. However, these groups also showed marked intercluster sequence conservation across them which were significantly different from that of previously published viper SPs. Because viper venom SPs exhibit a high degree of sequence similarity and yet exert profoundly different effects on the mammalian haemostatic system, no attempt was made to assign functionality to the new Echis ocellatus EoSPs on the basis of sequence alone. The extraordinary level of interspecific and intergeneric sequence conservation exhibited by the Echis ocellatus EoSPs and analogous serine proteases from other viper species leads us to speculate that antibodies to representative molecules should neutralise (that we will exploit, by epidermal DNA immunization) the biological function of this important group of venom toxins in vipers that are distributed throughout Africa, the Middle East, and the Indian subcontinent.

Antisnake Venom Activity of Hibiscus aethiopicus L. against Echis ocellatus and Naja n. nigricollis

The objective of the study is to investigate whether the Hibiscus aethiopicus L. plant has neutralization activity against venoms of two clinically important snakes. The H. aethiopicus was dried and extracted with water. Different assays were performed to evaluate the plant's acute toxicity and its anti-snake venom activities. The results showed that H. aethiopicus extract alone had no effect on the viability of C₂C₁₂ muscle cells, but significantly (P < .05) protected muscle cells against the toxic effects of E. ocellatus venom at 55, 150, and 300 μg/mL. The maximum protective effect of the extract was exhibited at 75 μg/mL. The extract significantly (P < .001) inhibited the cytotoxic effects of E. ocellatus venom at 300 μg/mL. All rabbits (n = 10) and guinea pigs (n = 10) were alive after the two weeks of given the lethal dosage 16 g/Kg of the H. aethiopicus extract herbal solution. No abnormal behaviour was observed of both groups of animals. All guinea pigs (n = 3) treated with venoms alone (5 mg/kg) died. However, all guinea pigs (n = 21) treated with venom (5 mg/kg) and the extract (400 to 1000 mg/kg) survived. Guinea pigs (n = 3) treated with Naja n. nigricollis venom alone (2.5 mg/kg) and guinea pigs (n = 21) venom with the extract (400 to 1000 mg/kg) died. The H. aethiopicus completely (100%) blocked the haemorrhagic activity of E. ocellatus in the egg embryo at 3.3 mg/mL of extract. These findings suggest that H. aethiopicus may contain an endogenous inhibitor of venom-induced haemorrhage.

New insights into the functions and N-glycan structures of factor X activator from Russell's viper venom

The coagulation factor X activator from Russell's viper venom (RVV-X) is a heterotrimeric glycoprotein. In this study, its three subunits were cloned and sequenced from the venom gland cDNAs of Daboia siamensis. The deduced heavy chain sequence contained a C-terminal extension with four additional residues to that published previously. Both light chains showed 77-81% identity to those of a homologous factor X activator from Vipera lebetina venom. Far-western analyses revealed that RVV-X could strongly bind protein S, in addition to factors X and IX. This might inactivate protein S and potentiate the disseminated intravascular coagulation syndrome elicited by Russell's viper envenomation. The N-glycans released from each subunit were profiled and sequenced by MALDI-MS and MS/MS analyses of the permethyl derivatives. All the glycans, one on each light chain and four on the heavy chain, showed a heterogeneous pattern, with a combination of variable terminal fucosylation and sialylation on multiantennary complex-type sugars. Amongst the notable features were the presence of terminal Lewis and sialyl-Lewis epitopes, as confirmed by western blotting analyses. As these glyco-epitopes have specific receptors in the vascular system, they possibly contribute to the rapid homing of RVV-X to the vascular system, as supported by the observation that slower and fewer fibrinogen degradation products are released by desialylated RVV-X than by native RVV-X.

Identification of cDNAs encoding viper venom hyaluronidases: Cross-generic sequence conservation of full-length and unusually short variant transcripts

The immobilisation of prey by snakes is most efficiently achieved by the rapid dissemination of venom from its site of injection into the blood stream. Hyaluronidase is a common component of snake venoms and has been termed the "venom spreading factor". In the absence of nucleotide or protein sequence data to confirm the functional identity of this venom component, we interrogated a venom gland EST database for the saw-scaled viper, Echis ocellatus (Nigeria), using the gene ontology (GO) term "carbohydrate metabolism". A single hyalurononglucosaminadase-activity matching sequence (EOC00242) was found and used to design PCR primers to acquire the full-length cDNA sequence. Although very different from the bee venom and mammalian hyaluronidase sequences, the E. ocellatus sequence retained all the catalytic, positional and structural residues that characterise this class of carbohydrate metabolising hydrolases. An extraordinarily high level of sequence identity (>95%) was observed in analogous venom gland cDNA sequences isolated (by PCR) from another saw-scaled viper species, E. pyramidum leakeyi (Kenya), and from the sahara horned viper, Cerastes cerastes cerastes (Egypt) and the puff adder, Bitis arietans (Nigeria). Smaller amplicons, lacking hyaluronidase catalytic residues because of 768 bp or 855 bp central deletions, appear to encode either truncated peptides without hyaluronidase activity, or are non-translated transcripts because they lack consensus translation initiating motifs.

Neutralization of the haemorrhagic activities of viperine snake venoms and venom metalloproteinases using synthetic peptide inhibitors and chelators

Envenoming by the West African saw-scaled viper, Echis ocellatus resembles that of most vipers, in that it results in local blistering, necrosis and sometimes life-threatening systemic haemorrhage. While effective against systemic envenoming, current antivenoms have little or no effect against local tissue damage. The major mediators of local venom pathology are the zinc-dependant snake venom metalloproteinases (SVMPs). The high degree of structural and functional homology between SVMPs and their mammalian relatives the matrix metalloproteinases (MMPs) suggests that substrate/inhibitor interactions between these subfamilies are likely to be analogous. In this study, four recently developed MMP inhibitors (MMPIs) (Marimastat, AG-3340, CGS-270 23A and Bay-12 9566) are evaluated in addition to three metal ion chelators (EDTA, TPEN and BAPTA) for their ability to inhibit the haemorrhagic activities of the medically important E. ocellatus venom and one of its haemorrhagic SVMPs, EoVMP2. As expected, the metal ion chelators significantly inhibited the haemorrhagic activities of both whole E. ocellatus venom and EoVMP2, while the synthetic MMPIs show more variation in their efficacies. These variations suggest that individual MMPIs show specificity towards SVMPs and that their application to the neutralization of local haemorrhage may require a synthetic MMPI mixture, ensuring that a close structural component for each SVMP is represented.

Venom gland EST analysis of the saw-scaled viper, Echis ocellatus, reveals novel α9β1 integrin-binding motifs in venom metalloproteinases and a new group of putative toxins, renin-like aspartic proteases

Echis ocellatus is the most medically important snake in West Africa. However, the composition of its venom and the differential contribution of these venom components to the severe haemorrhagic and coagulopathic pathology of envenoming are poorly understood. To address this situation we assembled a toxin transcriptome based upon 1000 expressed sequence tags (EST) from a cDNA library constructed from pooled venom glands of 10 individual E. ocellatus. We used a variety of bioinformatic tools to construct a fully annotated venom-toxin transcriptome that was interrogated with a combination of BLAST annotation, gene ontology cataloguing and disintegrin-motif searching. The results of these analyses revealed an unusually abundant and diverse expression of snake venom metalloproteinases (SVMP) and a broad toxin-expression profile including several distinct isoforms of bradykinin-potentiating peptides, phospholipase A(2), C-type lectins, serine proteinases and l-amino oxidases. Most significantly, we identified for the first time a conserved alpha(9)beta(1) integrin-binding motif in several SVMPs, and a new group of putative venom toxins, renin-like aspartic proteases.

Molecular Cloning of Disintegrin-like Transcript BA-5A from a Bitis arietans Venom Gland cDNA Library: A Putative Intermediate in the Evolution of the Long-Chain Disintegrin Bitistatin

We report the cloning and sequence analysis of BA-5A from a venom gland cDNA library of the puff adder, Bitis arietans, that encodes a novel ECD-disintegrin-like domain. BA-5A is a unique PII disintegrin. It contains the 16 cysteine residues that are conserved in all known disintegrin-like domains of ADAM proteins and snake venom metalloproteinases but lacks the cysteine-rich domain. These features suggest that BA-5A may represent an intermediate in the evolutionary pathway of the long disintegrin bitistatin and that removal of the cysteine-rich domain and loss of the PIII-specific disulfide bond were separate events along the structural diversification pathway of disintegrins, the former predating the latter. The protein family composition of the Bitis arietans venom, as determined by combination of reversed-phase HPLC and proteomic analysis, was as follows: Zn(2+)-metalloproteinase (38.5%), serine proteinase (19.5%), disintegrin (17.8%), C-type lectin-like (13.2%), PLA(2) (4.3%), Kunitz-type inhibitor (4.1%), cystatin (1.7%), and unknown (0.9%). BA-5A could not be detected in the venom proteome of Bitis arietans. The occurrence of this very low-abundance (< 0.05%) or nonexpressed disintegrin transcript indicates a hitherto unrecognized structural diversity of this protein family. Whether BA-5A plays a physiological role or represents an orphan protein which could eventually evolve a role in the adaptation of snakes to changing ecological niches and prey habits deserves further investigation.

Bioinformatics and multiepitope DNA immunization to design rational snake antivenom

BACKGROUND

Snake venom is a potentially lethal and complex mixture of hundreds of functionally diverse proteins that are difficult to purify and hence difficult to characterize. These difficulties have inhibited the development of toxin-targeted therapy, and conventional antivenom is still generated from the sera of horses or sheep immunized with whole venom. Although life-saving, antivenoms contain an immunoglobulin pool of unknown antigen specificity and known redundancy, which necessitates the delivery of large volumes of heterologous immunoglobulin to the envenomed victim, thus increasing the risk of anaphylactoid and serum sickness adverse effects. Here we exploit recent molecular sequence analysis and DNA immunization tools to design more rational toxin-targeted antivenom.

METHODS AND FINDINGS

We developed a novel bioinformatic strategy that identified sequences encoding immunogenic and structurally significant epitopes from an expressed sequence tag database of a venom gland cDNA library of Echis ocellatus, the most medically important viper in Africa. Focusing upon snake venom metalloproteinases (SVMPs) that are responsible for the severe and frequently lethal hemorrhage in envenomed victims, we identified seven epitopes that we predicted would be represented in all isomers of this multimeric toxin and that we engineered into a single synthetic multiepitope DNA immunogen (epitope string). We compared the specificity and toxin-neutralizing efficacy of antiserum raised against the string to antisera raised against a single SVMP toxin (or domains) or antiserum raised by conventional (whole venom) immunization protocols. The SVMP string antiserum, as predicted in silico, contained antibody specificities to numerous SVMPs in E. ocellatus venom and venoms of several other African vipers. More significantly, the antiserum cross-specifically neutralized hemorrhage induced by E. ocellatus and Cerastes cerastes cerastes venoms.

CONCLUSIONS

These data provide valuable sequence and structure/function information of viper venom hemorrhagins but, more importantly, a new opportunity to design toxin-specific antivenoms-the first major conceptual change in antivenom design after more than a century of production. Furthermore, this approach may be adapted to immunotherapy design in other cases where targets are numerous, diverse, and poorly characterized such as those generated by hypermutation or antigenic variation.

Molecular cloning of disintegrins from Cerastes vipera and Macrovipera lebetina transmediterranea venom gland cDNA libraries: insight into the evolution of the snake venom integrin-inhibition system

We report the cloning and sequence analysis of Cerastes vipera and Macrovipera lebetina transmediterranea cDNAs coding for short non-RGD (Arg-Gly-Asp) disintegrins and for dimeric disintegrin subunits. The mRNAs belong to the short-coding class, suggesting that these disintegrin mRNAs may be more widely distributed than previously thought. Our data also argue for a common ancestry of the mRNAs of short disintegrins and those coding for precursors of dimeric disintegrin chains. The Macrovipera lebetina transmediterranea dimeric disintegrin reported to inhibit the laminin-binding integrins alpha3beta1, alpha6beta1 and alpha7beta1 was analysed using a proteomic approach and was shown to bear MLD (Met-Leu-Asp) and VGD (Val-Gly-Asp) motifs. The results highlight the fact that disintegrins have evolved a restricted panel of integrin-blocking sequences that segregate with defined branches of the phylogenetic tree of the integrin alpha-chains, providing novel insights into the evolutionary adaptation of the snake venom antagonists to the ligand-binding sites of their target integrin receptors.

A catalog for the transcripts from the venomous structures of the caterpillar Lonomia obliqua: identification of the proteins potentially involved in the coagulation disorder and hemorrhagic syndrome

Accidents with the caterpillar Lonomia obliqua are often associated with a coagulation disorder and hemorrhagic syndrome in humans. In the present study, we have constructed cDNA libraries from two venomous structures of the caterpillar, namely the tegument and the bristle. High-throughput sequencing and bioinformatics analyses were performed in parallel. Over one thousand cDNAs were obtained and clustered to produce a database of 538 contigs and singletons (clusters) for the tegument library and 368 for the bristle library. We have thus identified dozens of full-length cDNAs coding for proteins with sequence homology to snake venom prothrombin activator, trypsin-like enzymes, blood coagulation factors and prophenoloxidase cascade activators. We also report cDNA coding for cysteine proteases, Group III phospholipase A2, C-type lectins, lipocalins, in addition to protease inhibitors including serpins, Kazal-type inhibitors, cystatins and trypsin inhibitor-like molecules. Antibacterial proteins and housekeeping genes are also described. A significant number of sequences were devoid of database matches, suggesting that their biologic function remains to be defined. We also report the N-terminus of the most abundant proteins present in the bristle, tegument, hemolymph, and "cryosecretion". Thus, we have created a catalog that contains the predicted molecular weight, isoelectric point, accession number, and putative function for each selected molecule from the venomous structures of L. obliqua. The role of these molecules in the coagulation disorder and hemorrhagic syndrome caused by envenomation with this caterpillar is discussed. All sequence information and the , including figures and tables with hyperlinks to FASTA-formatted files for each contig and the best match to the databases, are available at http://www.ncbi.nih.gov/projects/omes.

Antibody zymography: a novel adaptation of zymography to determine the protease-neutralising potential of specific antibodies and snake antivenoms

A common problem in the development of antibody-based therapeutics is the selection, usually from a large population, of specific antibodies with the desired function. One of our research objectives is to identify antibodies capable of neutralising the most important haemorrhagic and haemostasis-disruptive proteases from viper venom. Here, we describe a modification of conventional gelatin-zymography that permits the identification of antibodies capable of neutralising gelatinolytic proteases. We demonstrate that the gelatinolytic activity of viper venom proteases is neutralised by addition of viper antivenom to the matrix of conventional gelatin-zymograms. Venom protein gelatinolytic activity was unaffected by inclusion of antibody from control, non-immunised animals or immunoglobulin-depleted serum. The application of this antibody zymogram technique for future research on snake venoms is evaluated in the context of identified limitations.

Bitis gabonica (Gaboon viper) snake venom gland: toward a catalog for the full-length transcripts (cDNA) and proteins

The venom gland of the snake Bitis gabonica (Gaboon viper) was used for the first time to construct a unidirectional cDNA phage library followed by high-throughput sequencing and bioinformatic analysis. Hundreds of cDNAs were obtained and clustered into contigs. We found mostly novel full-length cDNA coding for metalloproteases (P-II and P-III classes), Lys49-phospholipase A2, serine proteases with essential mutations in the active site, Kunitz protease inhibitors, several C-type lectins, bradykinin-potentiating peptide, vascular endothelial growth factor, nucleotidases and nucleases, nerve growth factor, and L-amino acid oxidases. Two new members of the recently described short coding region family of disintegrin, displaying RGD and MLD motifs are reported. In addition, we have identified for the first time a cytokine-like molecule and a multi-Kunitz protease inhibitor in snake venoms. The CLUSTAL alignment and the unrooted cladograms for selected families of B. gabonica venom proteins are also presented. A significant number of sequences were devoid of database matches, suggesting that their biologic function remains to be identified. This paper also reports the N-terminus of the 15 most abundant venom proteins and the sequences matching their corresponding transcripts. The electronic version of this manuscript, available on request, contains spreadsheets with hyperlinks to FASTA-formatted files for each contig and the best match to the GenBank and Conserved Domain Databases, in addition to CLUSTAL alignments of each contig. We have thus generated a comprehensive catalog of the B. gabonica venom gland, containing for each secreted protein: (i) the predicted molecular weight, (ii) the predicted isoelectric point, (iii) the accession number, and (iv) the putative function. The role of these molecules is discussed in the context of the envenomation caused by the Gaboon viper.

Factor X activator from Vipera lebetina venom is synthesized from different genes

Vipera lebetina venom contains specific coagulant Factor X activator (VLFXA) that cleaves the Arg52-Ile53 bond in the heavy chain of human factor X. VLFXA is a glycoprotein that is composed of a heavy chain (HC) and two light chains (LC) linked by disulfide bonds. The complete amino acid sequences of the three chains of the factor X activator from V. lebetina snake venom are deduced from the nucleotide sequences of cDNAs encoding these chains. The full-length cDNA (2347 bp) sequence of the HC encodes an open reading frame (ORF) of 612 amino acids that includes signal peptide, propeptide and mature metalloproteinase with disintegrin-like and cysteine-rich domains. The light chain LC1 contains 123 and LC2 135 amino acid residues. Both light chains belong to the class of C-type lectin-like proteins. The N-termini of VLFXA chains and inner sequences of peptide fragments detected by liquid chromatography-electrospray ionization tandem mass spectrometry (LC MS/MS) from protein sequence are 100% identical to the sequences deduced from the cDNA. The molecular masses of tryptic fragments of VLFXA chains analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) also confirm the protein sequences deduced from the cDNAs. These are the first cloned factor X activator heavy and light chains. We demonstrate that the heavy and light chains are synthesized from different genes.

Cloning, expression, and structural analysis of recombinant BJcuL, a c-type lectin from the Bothrops jararacussu snake venom

The lactose-binding lectin from Bothrops jararacussu venom (BJcuL) is a homodimer belonging to group VII of the c-type animal lectins. BJcuL has also been shown to serve as an interesting tool for combating tumor progression by inhibiting cancer and endothelial cell growth. However, detailed structural studies of BJcuL and its biological mechanisms of cytotoxicity are yet to be reported, perhaps because of the non-availability of recombinant proteins in necessary quantities. Intending to increase the present information about structural and consequently the understating of biological studies, the cDNA coding for BJcuL from a venom gland has been cloned and sequenced. The mature protein-coding region was amplified by PCR with specific oligonucleotides, and subcloned into the pET-15b vector to express the recombinant BJcuL in Escherichia coli BL21 (DE3). The deduced amino acid sequence exhibits a high degree of sequence identity with c-type lectins (CTLs) and c-type lectin-like domains (CTLDs). An insoluble and inactive 18.5-kDa protein was overexpressed after 1.0mM IPTG induction. The recombinant BJcuL was recovered and denatured in a buffer with 6M urea and purified on a nickel-affinity column. Protein refolding was carried out on this column, during procedure purification, followed by dialysis against CTBS and then by gel filtration for separation of the active dimmer. The refolding process of rBJcuL and the analysis of its structure were confirmed by biological assay, circular dichroism, and MALDI-TOF.

Development of venom toxin-specific antibodies by DNA immunisation: rationale and strategies to improve therapy of viper envenoming

DNA vaccination induces potent cellular immune responses against infectious and parasitic intracellular pathogens. This paper illustrates that DNA immunisation protocols can be adapted to induce high titre antibody responses with potential to improve the treatment of systemic snake envenoming that kills 20000 people annually in Africa. Envenoming by the saw-scaled vipers and puff adders are responsible for the majority of these deaths. DNA sequences encoding haemorrhagic, pro- and anti-coagulant and other haemostasis-disruptive venom toxins from these vipers showed extensive cross-specific and cross-generic sequence and structural similarities. The predicted antigenic profiles of these toxin sequences are utilised to design DNA immunisation constructs to generate toxin-specific antibodies with potential to polyspecifically neutralise venoms from the most medically-important African vipers.

Cloning of a prothrombin activator-like metalloproteinase from the West African saw-scaled viper, Echis ocellatus

Systemic envenoming by the saw-scaled viper, Echis ocellatus, is responsible for more deaths than any other snake in West Africa. Despite its medical importance, there have been few investigations into the toxin composition of the venom of this viper. Here we describe the isolation of E. ocellatus venom gland cDNAs encoding a protein of 514 amino acids that showed 91% sequence similarity to Ecarin, a prothrombin-activating metalloproteinase from the venom of the East African viper, E. pyramidum leakeyi, that induces severe consumption coagulopathy. Structural similarities between the E. ocellatus metalloproteinase and analogues in venoms of related vipers suggest that antibodies raised to phylogenetically conserved E. ocellatus metalloproteinase domains may have potential for cross-specific and cross-generic neutralisation of analogous venom toxins.