Effect of the snake venom component crotamine on lymphatic endothelial cell responses and lymph transport.

OBJECTIVE: The pathology of snake envenomation is closely tied to the severity of edema in the tissue surrounding the area of the bite. Elucidating the mechanisms that promote the development of such severe edema is critical to a better understanding of how to treat this life-threatening injury. We focused on one of the most abundant venom components in North American viper venom, crotamine, and the effects it has on the cells and function of the lymphatic system. METHODS: We used RT-PCR to identify the location and relative abundance of crotamine's cellular targets (Kvα channels) within the tissues and cells of the lymphatic system. We used calcium flux, nitrate production, and cell morphometry to determine the effects of crotamine on lymphatic endothelial cells. We used tracer transport, node morphometry, and node deposition to determine the effects of crotamine on lymph transport in vivo. RESULTS: We found that genes that encode targets of crotamine are highly present in lymphatic tissues and cells and that there is a differential distribution of those genes that correlates with phasic contractile activity. We found that crotamine potentiates calcium flux in human dermal lymphatic endothelial cells in response to stimulation with histamine and sheer stress (but not alone) and that it alters the production of nitric oxide in response to shear as well as changes the level of F-actin polymerization of those same cells. Crotamine alters lymphatic transport of large molecular weight tracers to local lymph nodes and is deposited within the node mostly in the immediate subcapsular region. CONCLUSION: This evidence suggests that snake venom components may have an impact on the function of the lymphatic system. This needs to be studied in greater detail as there are numerous venom components that may have effects on aspects of the lymphatic system. This would not only provide basic information on the pathobiology of snakebite but also provide targets for improved therapeutics to treat snakebite.

Immunity to LuloHya and Lundep, the salivary spreading factors from Lutzomyia longipalpis, protects against Leishmania major infection.

Salivary components from disease vectors help arthropods to acquire blood and have been shown to enhance pathogen transmission in different model systems. Here we show that two salivary enzymes from Lutzomyia longipalpis have a synergist effect that facilitates a more efficient blood meal intake and diffusion of other sialome components. We have previously shown that Lundep, a highly active endonuclease, enhances parasite infection and prevent blood clotting by inhibiting the intrinsic pathway of coagulation. To investigate the physiological role of a salivary hyaluronidase in blood feeding we cloned and expressed a recombinant hyaluronidase from Lu. longipalpis. Recombinant hyaluronidase (LuloHya) was expressed in mammalian cells and biochemically characterized in vitro. Our study showed that expression of neutrophil CXC chemokines and colony stimulating factors were upregulated in HMVEC cells after incubation with LuloHya and Lundep. These results were confirmed by the acute hemorrhage, edema and inflammation in a dermal necrosis (dermonecrotic) assay involving a massive infiltration of leukocytes, especially neutrophils, in mice co-injected with hemorrhagic factor and these two salivary proteins. Moreover, flow cytometry results showed that LuloHya and Lundep promote neutrophil recruitment to the bite site that may serve as a vehicle for establishment of Leishmania infection. A vaccination experiment demonstrated that LuloHya and Lundep confer protective immunity against cutaneous leishmaniasis using the Lu. longipalpis-Leishmania major combination as a model. Animals (C57BL/6) immunized with LuloHya or Lundep showed minimal skin damage while lesions in control animals remained ulcerated. This protective immunity was abrogated when B-cell-deficient mice were used indicating that antibodies against both proteins play a significant role for disease protection. Rabbit-raised anti-LuloHya antibodies completely abrogated hyaluronidase activity in vitro. Moreover, in vivo experiments demonstrated that blocking LuloHya with specific antibodies interferes with sand fly blood feeding. This work highlights the relevance of vector salivary components in blood feeding and parasite transmission and further suggests the inclusion of these salivary proteins as components for an anti-Leishmania vaccine.

CatroxMP-II: a heme-modulated fibrinogenolytic metalloproteinase isolated from Crotalus atrox venom.

It has been recently demonstrated that the hemotoxic venom activity of several species of snakes can be inhibited by carbon monoxide (CO) or a metheme forming agent. These and other data suggest that the biometal, heme, may be attached to venom enzymes and may be modulated by CO. A novel fibrinogenolytic metalloproteinase, named CatroxMP-II, was isolated and purified from the venom of a Crotalus atrox viper, and subjected to proteolysis and mass spectroscopy. An ion similar to the predicted singly charged m/z of heme at 617.18 was identified. Lastly, CORM-2 (tricarbonyldichlororuthenium (II) dimer, a CO releasing molecule) inhibited the fibrinogenolytic effects of CatroxMP-II on coagulation kinetics in human plasma. In conclusion, we present the first example of a snake venom metalloproteinase that is heme-bound and CO-inhibited.

Crotamine-like from Southern Pacific rattlesnake (Crotalus oreganus helleri) Venom acts on human leukemia (K-562) cell lines and produces ultrastructural changes on mice adrenal gland.

Crotamine is a cationic, non-enzymatic, protein integrating a minor family of myotoxins, composed of 42 amino acid residues, described in Viperidae and Crotalidae snake's families that has been used in neuroscience research, drug progressing and molecular diversity reports. Crotamine-like protein (CLP) from C.o.helleri venom was isolated in fraction 5 from 7 peaks obtained by sulfopropyl waters protein pak cationic exchange column. In tricine-SDS-PAGE under non-reduced conditions this CLP showed a single band of ~8 kDa molecular weight. CLP induced toxicity of K-562 cells with a CC50 of 11.09 µM. In mice adrenal gland after 24 h of CLP injection, cortical cells exhibited swollen mitochondria with scarce tubular cristae, some elements of smooth and rough endoplasmic reticula, widened nuclear envelope, slightly osmiophilic lipid droplets, and autophagic vacuoles. In some areas cortical cells plasma membrane and endothelial walls disappeared, which indicated a necrosis process. In other areas, endothelial cell cytoplasm did not present the normal caveolae and pinocytotic vesicles. To our knowledge, this is the first report on mice adrenal gland damages, caused by the injection of CLP from rattlesnakes. Our results propose that adrenal cortex lesions may be significant in the envenoming etiopathogenesis by CLP.

Gene expression profiling of the venom gland from the Venezuelan mapanare (Bothrops colombiensis) using expressed sequence tags (ESTs).

BACKGROUND: Bothrops colombiensis is a highly dangerous pit viper and responsible for over 70% of snakebites in Venezuela. Although the composition in B. colombiensis venom has been identified using a proteome analysis, the venom gland transcriptome is currently lacking. RESULTS: We constructed a cDNA library from the venom gland of B. colombiensis, and a set of 729 high quality expressed sequence tags (ESTs) was identified. A total number of 344 ESTs (47.2% of total ESTs) was related to toxins. The most abundant toxin transcripts were metalloproteinases (37.5%), phospholipases A2s (PLA2, 29.7%), and serine proteinases (11.9%). Minor toxin transcripts were linked to waprins (5.5%), C-type lectins (4.1%), ATPases (2.9%), cysteine-rich secretory proteins (CRISP, 2.3%), snake venom vascular endothelium growth factors (svVEGF, 2.3%), L-amino acid oxidases (2%), and other putative toxins (1.7%). While 160 ESTs (22% of total ESTs) coded for translation proteins, regulatory proteins, ribosomal proteins, elongation factors, release factors, metabolic proteins, and immune response proteins. Other proteins detected in the transcriptome (87 ESTs, 11.9% of total ESTs) were undescribed proteins with unknown functions. The remaining 138 (18.9%) cDNAs had no match with known GenBank accessions. CONCLUSION: This study represents the analysis of transcript expressions and provides a physical resource of unique genes for further study of gene function and the development of novel molecules for medical applications.

The characterization of trans-pecos copperhead (Agkistrodon contortrix pictigaster) venom and isolation of two new dimeric disintegrins.

The vast amounts of toxins within the venom of snakes, while known to cause medical emergencies, display various biological functions. Trans-pecos copperhead (Agkistrodon contortrix pictigaster) crude venom separated by cation-exchange chromatography showed several fractions with fibrinolytic, hemorrhagic, gelatinase and platelet activities. Venom fractions 1, 2, 4, 5, and 12-17 contained fibrinolytic activity. Venom fractions 1, 2, 5 and 12-14 had hemorrhagic activity. Fractions 1, 2, 12, 13 and 17 contained gelatinase activity. Reverse-Phase C18 High Performance Liquid Chromatography was also used to purify and isolated disintegrins from this venom. Anti-platelet aggregation activity of the C18 fractions collected and performed on whole human blood showed that they inhibited platelet aggregation in presence of several agonists. Results from both SDS-PAGE and N-terminal sequencing determined that pictistatin 1 obtained from the Trans-Pecos copperhead venom was a dimeric disintegrin, and pictistatin 2 was a heterodimeric disintegrin. The molecules with anti-platelet activity could be considered in the development of more effective drugs, for numerous blood-related diseases such as stroke, heart attacks, thrombosis, and other medical conditions. In this study, we are presenting the first report of the purification, isolation, and partial characterization of two new dimeric disintegrins isolated from the venom of trans-pecos copperhead.

Morulustatin, A Disintegrin that Inhibits ADP-Induced Platelet Aggregation, Isolated from the Mexican Tamaulipan Rock Rattlesnake (Crotalus lepidus morulus).

The Tamaulipan rock rattlesnake (Crotalus lepidus morulus) is a montane snake that occurs in the humid pine-oak forest and the upper cloud forest of the Sierra Madre Oriental in southwestern Tamaulipas, central Nuevo Leon, and southeastern Coahuila in Mexico. Venom from this rattlesnake was fractionated by High-Performance Liquid Chromatography for the purpose of discovering disintegrin molecules. Disintegrins are non-enzymatic, small molecular weight peptides that interfere with cell-cell and cell-matrix interactions by binding to various cell receptors. Eleven fractions were collected by anion exchange chromatography and pooled into six groups (I, II, III, IV, V, and VI). Proteins of the six groups were analyzed by SDS-PAGE and western blot using antibodies raised against a disintegrin. The antibodies recognized different protein bands in five (II, III, IV, V, and VI) of six groups in a molecular mass range of 7 to 105 kDa. Western blot analysis revealed fewer protein bands in the higher molecular mass range and two bands in the disintegrin weight range in group II compared with the other four groups. Proteins in group II were further separated into nine fractions using reverse phase C18 chromatography. Fraction 4 inhibited platelet aggregation and was named morulustatin, which exhibited a single band with a molecular mass of approximately 7 kDa. Mass spectrometry analysis of fraction 4 revealed the identification of disintegrin peptides LRPGAQCADGLCCDQCR (MH+ 2035.84) and AGEECDCGSPANCCDAATCK (MH+ 2328.82). Morulustatin inhibited ADP-induced platelet aggregation in human whole blood and was concentration-dependent with an IC50 of 89.5 nM ± 12.

Snake venom cysteine-rich secretory protein from Mojave rattlesnake venom (Css-CRiSP) induces acute inflammatory responses on different experimental models.

Snake venoms contain various molecules known for activating innate immunity and causing local effects associated with increased vascular permeability, such as vascular leakage and edema, common symptoms seen in snakebite envenomings. We have demonstrated that snake venom cysteine-rich secretory proteins (svCRiSPs) from North American pit vipers increase vascular permeability. This study aimed to explore the functional role of CRiSP isolated from Mojave rattlesnake (Crotalus scutulatus scutulatus) venom (Css-CRiSP) on the activation of inflammatory responses in different models. We measured the release of inflammatory mediators in cultured human dermal blood endothelial cells (HDBEC), lymphatic endothelial cells (HDLEC) and monocyte-derived macrophages (MDM) at 0.5, 1, 3, 6, and 24 h after treatment with Css-CRiSP (1 µM). We also determined the acute inflammatory response in BALB/c mice 30 min after intraperitoneal injection of the toxin (2 µg/mouse). Css-CRiSP induced the production of IL-8 and IL-6, but not TNF-α, in HDBEC and HDLEC in a time-dependent manner. In addition, Css-CRiSP significantly enhanced the production of IL-6, TNF-α, IL-8, and IL-1ß in MDM. Moreover, it caused a remarkable increase of chemotactic mediators in the exudates of experimental mice. Our results reveal that Css-CRiSPs can promote a sustained release of inflammatory mediators on cell lines and an acute activation of innate immunity in a murine model. These findings contribute to the growing body of evidence supporting the involvement of svCRiSPs in the augmentation of envenomation effects, specifically, the role of svCRiSPs in inducing vascular dysfunction, initiating early inflammatory responses, and facilitating the activation of leukocytes and releasing mediators. These findings will lead to a better understanding of the pathophysiology of envenoming by Mojave rattlesnakes, allowing the development of more efficient therapeutic strategies.

Proteomic Profiling of Extracellular Vesicles Isolated from Plasma and Peritoneal Exudate in Mice Induced by Crotalus scutulatus scutulatus Crude Venom and Its Purified Cysteine-Rich Secretory Protein (Css-CRiSP).

Increased vascular permeability is a frequent outcome of viperid snakebite envenomation, leading to local and systemic complications. We reported that snake venom cysteine-rich secretory proteins (svCRiSPs) from North American pit vipers increase vascular permeability both in vitro and in vivo. They also induce acute activation of several adhesion and signaling molecules that may play a critical role in the pathophysiology of snakebites. Extracellular vesicles (EVs) have gained interest for their diverse functions in intercellular communication, regulating cellular processes, blood-endothelium interactions, vascular permeability, and immune modulation. They also hold potential as valuable biomarkers for diagnosing, predicting, and monitoring therapeutic responses in different diseases. This study aimed to identify proteins in peritoneal exudate and plasma EVs isolated from BALB/c mice following a 30 min post-injection of Crotalus scutulatus scutulatus venom and its purified CRiSP (Css-CRiSP). EVs were isolated from these biofluids using the EVtrap method. Proteomic analysis of exudate- and plasma-derived EVs was performed using LC-MS/MS. We observed significant upregulation or downregulation of proteins involved in cell adhesion, cytoskeleton rearrangement, signal transduction, immune responses, and vesicle-mediated transports. These findings suggest that svCRiSPs play a crucial role in the acute effects of venom and contribute to the local and systemic toxicity of snakebites.

Negative inotropic mechanisms of ß-cardiotoxin in cardiomyocytes by depression of myofilament ATPase activity without activation of the classical ß-adrenergic pathway.

Beta-cardiotoxin (ß-CTX) from the king cobra venom (Ophiophagus hannah) was previously proposed as a novel ß-adrenergic blocker. However, the involvement of ß-adrenergic signaling by this compound has never been elucidated. The objectives of this study were to investigate the underlying mechanisms of ß-CTX as a ß-blocker and its association with the ß-adrenergic pathway. The effects of ß-CTX on isolated cardiac myocyte functions, calcium homeostasis, the phosphorylation level of targeted proteins, and the myofibrillar ATPase activity were studied. Healthy Sprague Dawley rats were used for cardiomyocytes isolation. Like propranolol, ß-CTX attenuated the cardiomyocyte inotropy and calcium transient alterations as induced by isoproterenol stimulation. In contrast, these effects were not observed in forskolin-treated cells. Interestingly, cardiomyocytes treated with ß-CTX showed no changes in phosphorylation level at any PKA-targeted sites in the myofilaments as demonstrated in Western blot analysis. The skinned fibers study revealed no change in myofilament kinetics by ß-CTX. However, this protein exhibited the direct inhibition of myofibrillar ATPase activity with calcium de-sensitization of the enzyme. In summary, the negative inotropic mechanism of ß-CTX was discovered. ß-CTX exhibits an atypical ß-blocker mechanism. These properties of ß-CTX may benefit in developing a novel agent aid to treat hypertrophic cardiomyopathy.

Evaluation of Signaling Pathways Profiling in Human Dermal Endothelial Cells Treated by Snake Venom Cysteine-Rich Secretory Proteins (svCRiSPs) from North American Snakes Using Reverse Phase Protein Array (RPPA).

Cysteine-Rich Secretory Proteins (CRiSPs) are typically found in many snake venoms; however, the role that these toxins play in the pathophysiology of snakebites is still unclear. Herein, we compared the effects of snake venom CRiSPs (svCRiSPs) from the most medically important species of North American snakes on endothelial cell permeability and vascular permeability. We used reverse phase protein array (RPPA) to identify key signaling molecules on human dermal lymphatic (HDLECs) and blood (HDBECs) endothelial cells treated with svCRiSPs. The results showed that Css-CRiSP isolated from Crotalus scutulatus scutulatus and App-CRiSP from Agkistrodon piscivorus piscivorus are the most potent causes of increase vascular and endothelial permeability in comparison with other svCRiSPs used in this study. We examined the protein expression levels and their activated phosphorylation states in HDLECs and HDBECs induced by App-CRiSP and Css-CRiSP using RPPA. Interestingly, both App-CRiSP and Css-CRiSP induced caveolin-1 expression in HDBECs. We also found that stimulating HDBECs with Css-CRiSP and App-CRiSP significantly induced the phosphorylation of mTOR and Src, respectively. In HDLECs, Css-CRiSP significantly downregulated the expression of N-Cadherin and phospholipase C-gamma, while App-CRiSP significantly enhanced Akt and JNK phosphorylation. These results suggest that the increased endothelial permeability in HDLECs and HDBECs by Css-CRiSP and App-CRiSP may occur through different pathways.

Examination of the Efficacy and Cross-Reactivity of a Novel Polyclonal Antibody Targeting the Disintegrin Domain in SVMPs to Neutralize Snake Venom.

Snake envenomation can result in hemorrhage, local necrosis, swelling, and if not treated properly can lead to adverse systemic effects such as coagulopathy, nephrotoxicity, neurotoxicity, and cardiotoxicity, which can result in death. As such, snake venom metalloproteinases (SVMPs) and disintegrins are two toxic components that contribute to hemorrhage and interfere with the hemostatic system. Administration of a commercial antivenom is the common antidote to treat snake envenomation, but the high-cost, lack of efficacy, side effects, and limited availability, necessitates the development of new strategies and approaches for therapeutic treatments. Herein, we describe the neutralization ability of anti-disintegrin polyclonal antibody on the activities of isolated disintegrins, P-II/P-III SVMPs, and crude venoms. Our results show disintegrin activity on platelet aggregation in whole blood and the migration of the SK-Mel-28 cells that can be neutralized with anti-disintegrin polyclonal antibody. We characterized a SVMP and found that anti-disintegrin was also able to inhibit its activity in an in vitro proteolytic assay. Moreover, we found that anti-disintegrin could neutralize the proteolytic and hemorrhagic activities from crude Crotalus atrox venom. Our results suggest that anti-disintegrin polyclonal antibodies have the potential for a targeted approach to neutralize SVMPs in the treatment of snakebite envenomations.

Proteomic Identification and Quantification of Snake Venom Biomarkers in Venom and Plasma Extracellular Vesicles.

The global exploration of snakebites requires the use of quantitative omics approaches to characterize snake venom as it enters into the systemic circulation. These omics approaches give insights into the venom proteome, but a further exploration is warranted to analyze the venom-reactome for the identification of snake venom biomarkers. The recent discovery of extracellular vesicles (EVs), and their critical cellular functions, has presented them as intriguing sources for biomarker discovery and disease diagnosis. Herein, we purified EV's from the snake venom (svEVs) of Crotalus atrox and C. oreganus helleri, and from plasma of BALB/c mice injected with venom from each snake using EVtrap in conjunction with quantitative mass spectrometry for the proteomic identification and quantification of svEVs and plasma biomarkers. Snake venom EVs from C. atrox and C. o. helleri were highly enriched in 5' nucleosidase, L-amino acid oxidase, and metalloproteinases. In mouse plasma EVs, a bioinformatic analysis for revealed upregulated responses involved with cytochrome P450, lipid metabolism, acute phase inflammation immune, and heat shock responses, while downregulated proteins were associated with mitochondrial electron transport, NADH, TCA, cortical cytoskeleton, reticulum stress, and oxidative reduction. Altogether, this analysis will provide direct evidence for svEVs composition and observation of the physiological changes of an envenomated organism.

Suppression of cardiomyocyte functions by ß-CTX isolated from the Thai king cobra (Ophiophagus hannah) venom via an alternative method.

BACKGROUND: Beta-cardiotoxin (ß-CTX), the three-finger toxin isolated from king cobra (Ophiophagus hannah) venom, possesses ß-blocker activity as indicated by its negative chronotropy and its binding property to both ß-1 and ß-2 adrenergic receptors and has been proposed as a novel ß-blocker candidate. Previously, ß-CTX was isolated and purified by FPLC. Here, we present an alternative method to purify this toxin. In addition, we tested its cytotoxicity against different mammalian muscle cell types and determined the impact on cardiac function in isolated cardiac myocyte so as to provide insights into the pharmacological action of this protein. METHODS: ß-CTX was isolated from the crude venom of the Thai king cobra using reverse-phased and cation exchange HPLC. In vitro cellular viability MTT assays were performed on mouse myoblast (C2C12), rat smooth muscle (A7r5), and rat cardiac myoblast (H9c2) cells. Cell shortening and calcium transient dynamics were recorded on isolated rat cardiac myocytes over a range of ß-CTX concentration. RESULTS: Purified ß-CTX was recovered from crude venom (0.53% w/w). MTT assays revealed 50% cytotoxicity on A7r5 cells at 9.41 ± 1.14 µM (n = 3), but no cytotoxicity on C2C12 and H9c2 cells up to 114.09 µM. ß-CTX suppressed the extend of rat cardiac cell shortening in a dose-dependent manner; the half-maximal inhibition concentration was 95.97 ± 50.10 nM (n = 3). In addition, the rates of cell shortening and re-lengthening were decreased in ß-CTX treated myocytes concomitant with a prolongation of the intracellular calcium transient decay, indicating depression of cardiac contractility secondary to altered cardiac calcium homeostasis. CONCLUSION: We present an alternative purification method for ß-CTX from king cobra venom. We reveal cytotoxicity towards smooth muscle and depression of cardiac contractility by this protein. These data are useful to aid future development of pharmacological agents derived from ß-CTX.

Biological activities of a new crotamine-like peptide from Crotalus oreganus helleri on C2C12 and CHO cell lines, and ultrastructural changes on motor endplate and striated muscle.

Crotamine and crotamine-like peptides are non-enzymatic polypeptides, belonging to the family of myotoxins, which are found in high concentration in the venom of the Crotalus genus. Helleramine was isolated and purified from the venom of the Southern Pacific rattlesnake, Crotalus oreganus helleri. This peptide had a similar, but unique, identity to crotamine and crotamine-like proteins isolated from other rattlesnakes species. The variability of crotamine-like protein amino acid sequences may allow different toxic effects on biological targets or optimize the action against the same target of different prey. Helleramine was capable of increasing intracellular Ca2+ in Chinese Hamster Ovary (CHO) cell line. It inhibited cell migration as well as cell viability (IC50 = 11.44 µM) of C2C12, immortalized skeletal myoblasts, in a concentration dependent manner, and promoted early apoptosis and cell death under our experimental conditions. Skeletal muscle harvested from mice 24 h after helleramine injection showed contracted myofibrils and profound vacuolization that enlarged the subsarcolemmal space, along with loss of plasmatic and basal membrane integrity. The effects of helleramine provide further insights and evidence of myotoxic activities of crotamine-like peptides and their possible role in crotalid envenomings.

The neutralization efficacy of expired polyvalent antivenoms: An alternative option.

The expense of production and distribution of snakebite antivenom, as well as its relatively infrequent use, has caused antivenom to be increasingly difficult to obtain and ultimately producing an alarming global shortage. Unused, expired antivenom may represent a significant, untapped resource to ameliorate this crisis. This study examines the efficacy of expired antivenom over time using in vitro, whole blood clotting, and platelet function statistics. Representatives from three years for four different global brands of polyvalent antivenom were chosen and tested against their corresponding venoms as well as other venoms that could display cross-reactivity. These antivenoms include Wyeth Polyvalent (U.S.; exp. 1997, 2001, 2003), Antivipmyn® (Mexico; exp. 2005, 2013, 2017), Biotecfars Polyvalent (Venezuela; exp. 2010, 2014, 2016), and SAIMR (South Africa; exp. 1997, 2005, 2017). Venoms of species tested were Crotalus atrox against Wyeth; C. atrox and Crotalus vegrandis against Antivipmyn®; C. atrox, C. vegrandis and Bothrops colombiensis against Biotecfar; and Bitis gabonica and Echis carinatus against South African Institute for Medical Research (SAIMR). Parameters recorded were activated clotting time (ACT), clotting rate (CR), and platelet function (PF). Preliminary results are encouraging as the antivenoms maintained significant efficacy even 20 y after their expiration date. We anticipate these results will motivate further studies and provide hope in the cases of snakebite emergencies when preferable treatments are unavailable.

The isolation and characterization of a new snake venom cysteine-rich secretory protein (svCRiSP) from the venom of the Southern Pacific rattlesnake and its effect on vascular permeability.

A novel snake venom cysteine-rich secretory protein (svCRiSP), Hellerin, was purified from C. o. helleri venom using sequential reverse phase and cation-exchange chromatography. Gel electrophoresis, N-terminal sequencing, and LC-MS/MS sequencing identified a single protein with a molecular mass of approximately 24.8 kDa and confirmed its identity as a svCRiSP. Hellerin had cytotoxic effects on human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner but not in human dermal lymphatic endothelial cells (HDLECs) and human dermal blood endothelial cells (HDBECs). Hellerin produced a dramatic increase in both blood vascular permeability in vivo, and in the trans-epithelial permeability of cultured HDLEC and HDBEC cells. This is the first study that describes the effect of a svCRiSP on vascular, blood and lymphatic permeability.

Mutacytin-1, a New C-Type Lectin-Like Protein from the Venezuelan Cuaima (Lachesis muta muta Linnaeus, 1766) (Serpentes: Viperidae) Snake Venom Inducing Cardiotoxicity in Developing Zebrafish (Danio rerio) Embryos.

Envenomation by the Venezuelan bushmaster snake (Lachesis muta muta) (Serpentes: Viperidae) is characterized by local and cardiac alterations. This study investigates the in vivo cardiac dysfunction, tissue destruction, and cellular processes triggered by Lachesis muta muta snake crude venom and a C-type lectin (CTL)-like toxin named Mutacytin-1 (MC-1). The 28 kDa MC-1 was obtained by molecular exclusion, ion exchange, and C-18 (checking pureness) reverse-phase chromatographies. N-terminal sequencing of the first eight amino acids (NNCPQ LLM) revealed 100% identity with Mutina (CTL-like) isolated from Lachesis stenophrys, which is a Ca2+-dependent-type galactoside-binding lectin from Bothrops jararaca and CTL BpLec from Bothrops pauloensis. The cardiotoxicity in zebrafish of MC-1 was evaluated by means of specific phenotypic expressions and larvae behavior at 5, 15, 30, 40 and 60 min post-treatment. The L. muta muta venom and MC-1 also produced heart rate/rhythm alterations, circulation modifications, and the presence of thrombus and apoptotic phenomenon with pericardial damages. Acridine orange (100 µg/mL) was used to visualize apoptosis cellular process in control and treated whole embryos. The cardiotoxic alterations happened in more than 90% of all larvae under the action of L. muta muta venom and MC-1. The findings have demonstrated the potential cardiotoxicity by L. muta muta venom, suggesting the possibility of cardiovascular damages to patients after bushmaster envenoming.

Opossum peptide that can neutralize rattlesnake venom is expressed in Escherichia coli.

An eleven amino acid ribosomal peptide was shown to completely neutralize Western Diamondback Rattlesnake (Crotalus atrox) venom in mice when a lethal dose of the venom was pre-incubated with the peptide prior to intravenous injection. We have expressed the peptide as a concatenated chain of peptides and cleaved them apart from an immobilized metal affinity column using a protease. After ultrafiltration steps, the mixture was shown to partially neutralize rattlesnake venom in mice. Preliminary experiments are described here that suggest a potential life-saving therapy could be developed. To date, no recombinant therapies targeting cytotoxic envenomation have been reported. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:81-86, 2017.