Scorpion Tityus Serrulatus Research Articles

Investigation of the modulation of glutamate release by sodium channels using neurotoxins

The modulation of neurotransmitter release by calcium channels is well established, yet, sodium channels were regarded mainly as charge carriers. Many lines of evidence suggest a more fine-tuning role played by sodium channels. Using rat cerebrocortical isolated nerve endings (synaptosomes) and two toxins that have separate sites of action on sodium channels and provoke distinct changes in channel kinetics, we were able to show that depending on the rate of increase in channel conductance, the outcome in terms of neurotransmitter release and calcium channel types coupled to that event are different. Mainly, our study focused on veratridine, an alkaloid from lilaceous plants that binds to sodium channel toxin site 2, and tityustoxin, a toxin purified from the venom of the Brazilian yellow scorpion Tityus serrulatus that binds to site 3. Veratridine induces a slower increase in intrasynaptosomal sodium and calcium concentrations, slower depolarization, delayed exocytosis and a slower and predominantly calcium-independent glutamate release, when compared to tityustoxin. Thus, we have used these two toxins to investigate the events that start with sodium entry and culminate with the release of glutamate in isolated nerve endings (synaptosomes) from rat cerebral cortex. With that in mind we measured intrasynaptosomal free sodium concentration [Na +] i, intrasynaptosomal free calcium concentration [Ca 2+] i, membrane potential, exocytosis and glutamate release using fluorescent probes.

Myocardial necrosis after envenomation by the scorpion Tityus serrulatus

A 4 years old boy died a few hours after he had been stung by a scorpion ( Tityus serrulatus). At necropsy, there were multiple foci of coagulative myocytolysis in the myocardium and pulmonary oedema. Myocardial necrosis was probably associated with the sympathetic storm induced by scorpion envenomation, and may have contributed to cardiac failure and death.

Molecular basis for the cross-reactivity of antibodies elicited by a natural anatoxin with α- and β-toxins from the venom of Tityus serrulatus scorpion

A non-toxic protein (TsNTxP) isolated from the venom of the noxious scorpion Tityus serrulatus (Ts) induces polyclonal antibodies cross-reactive with several toxins from the venom, in sharp contrast to anti-toxin antibodies which are toxin specific. To try to uncover the molecular basis for these unusual properties, peptide scanning experiments were performed and indicated that the N- and C-terminal parts of TsNTxP enclose continuous epitopes (residues 1–15 and 47–61). Antibodies raised against peptides corresponding to these two regions were found to have neutralizing properties against a mixture of all toxic proteins from the T. serrulatus venom, indicating that residues 1–15 and 47–61 correspond to neutralizing epitopes. The identification of key antigenic residues within these two epitopes revealed that several of them are well conserved in the amino-acid sequences of the three main toxins (Ts II, Ts IV and Ts VII) from the venom: Glu 3, Tyr 5, Asp 8, Asp 50, Trp 55 and Lys 61. A single key-residue (Glu 58) is unique to TsNTxP. By using homology modeling, a model of the three-dimensional structure of TsNTxP was obtained. The antigenically important residues from TsNTxP were found to be surface exposed, with five of them clustered on the facet of the protein reported to enclose the active site of toxins. Residues equivalent to the seven key-residues of the anatoxin were also found to be exposed in the active toxins from T. serrulatus venom. These results show that antibodies elicited by the non-toxic protein TsNTxP recognized, within the N- and C-terminal parts of toxins of T. serrulatus, conserved and surface exposed residues which might also be involved in the toxic action of the proteins.

Estudo histopatológico do pâncreas de ratos intoxicados pelo veneno bruto do escorpião Tityus serrulatus.

<p><span class="texto">Modificações no teor de vários componentes da secreção pancreática e alterações histopatológicas desse órgão são verificadas após injeção de veneno do escorpião Tityus serrulatus em ratos. Entre essas alterações, podem ser citadas pancreatite aguda e crônica após uma única injeção de veneno. Os achados compatíveis com pancreatite aguda foram encontrados a partir de 10 minutos após a intoxicação e, 20 dias após, a maioria dos animais exibiu achados histológicos típicos de pancreatite crônica. O objetivo do presente trabalho foi determinar a cinética das alterações pancreáticas que ocorrem ao longo do tempo, após injeção endovenosa de veneno bruto de escorpião em ratos. Os animais, após jejum de 24-48 horas, receberam uma injeção venosa, pela veia peniana, de 0,2 ml de uma solução de cloreto de sódio (grupo controle) ou de 0,2 ml de uma solução contendo 300 mg/ml de veneno bruto do escorpião Tityus serrulatus (60 mg/animal). Os animais foram sacrificados em grupos de 5 a 10 cada, aos 10, 20 e 40 minutos e 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18 e 20 dias após a injeção. O pâncreas foi retirado e processado para estudo histológico. Pancreatite aguda (PA) foi observada nos grupos sacrificados após 10, 20 e 40 minutos, 24 e 48 horas após a injeção. Achados compatíveis com pancreatite crônica (PC) foram detectados nos animais sacrificados entre 4 a 20 dias após a injeção. No grupo de animais sacrificados 3 dias após, observaram-se, no mesmo animal e, às vezes, no mesmo corte histológico, alterações características de PA (degranulação, vacuolização acinar, infiltração difusa de linfócitos e lesões granulomatosas) e, surpreendentemente, de PC (dilatação ductal com rolhas protéicas, hiperplasia ductal e hiperplasia dos linfonodos peripancreáticos), caracterizando a fase de transição da pancreatite aguda para pancreatite crônica. Todos os grupos apresentaram mobilização e degranulação de mastócitos, sugerindo a participação dessas células na etiopatogênese dessas lesões. Em 50% dos animais dos grupos sacrificados aos 18 e 20 dias após o veneno foram também observados, ao lado das lesões inflamatórias, hiperplasia das ilhotas de Langerhans.</span></p>

Induction of neutralizing antibodies against Tityus serrulatus scorpion toxins by immunization with a mixture of defined synthetic epitopes

We have used the Spot method of multiple peptide synthesis to prepare sets of immobilized overlapping peptides of uniform size (15 mer), covering the complete amino acid sequences of TsNTxP a non-toxic and immunogenic protein and TsIV, an α-type toxin that is the major lethal component of the venom of scorpion Tityus serrulatus. Anti-TsNTxP antibodies binding to peptides, revealed three antigenic regions, one in the N-terminal, the second in the central part and the other in the C-terminal part of TsNTxP. One peptide epitope in the C-terminal part of TsIV was identified with anti-TsIV neutralizing rabbit antibodies. Anti-peptide antibodies were raised against these four peptides all together covalently coupled to keyhole limpet hemocyanin (KLH) and found to neutralize in vitro the toxic effects of the T. serrulatus venom. Quantities of venom equivalent to 13.5 LD 50 were effectively neutralized by 1 ml of the anti-peptide serum. The antigenic specificities of the anti-peptides were compared by an indirect enzyme-linked immunosorbent assay (ELISA) using synthetic peptides and crude venoms from T. serrulatus, T. bahiensis, T. cambridgei, T. stigmurus, Androctonus autralis Hector and Centruroides sculpturatus to coat the microtitration plates. The anti-peptide antibodies had a comparable high reactivity with the crude venom of T. serrulatus, moderate binding to T. bahiensis, T. cambridgei, T. stigmurus and Centruroides sculpturatus venoms but were unable to recognize the venom of Androctonus autralis Hector. These results show that by using peptides derived from the sequence of scorpion toxins, the generation of anti-peptide antibodies able to neutralize the cognate venom appears to be an alternative strategy for the easy preparation of antivenoms.

Moving pieces in a proteomic puzzle: mass fingerprinting of toxic fractions from the venom of Tityus serrulatus (Scorpiones, Buthidae).

Scorpion venoms are very complex mixtures of molecules, most of which are peptides that display different kinds of biological activity. These venoms have been studied in the light of their pharmacological targets and their constituents are able to bind specifically to a variety of ionic channels located in prey tissues, resulting in neurotoxic effects. Toxins that modulate Na(+), K(+), Ca(++) and Cl(-) currents have been described in scorpion venoms. Mass spectrometry was employed to analyze toxic fractions from the venom of the Brazilian scorpion Tityus serrulatus in order to shed light on the molecular composition of this venom and to facilitate the search for novel pharmacologically active compounds. T. serrulatus venom was first subjected to gel filtration to separate its constituents according to their molecular size. The resultant fractions II and III, which account for 90 and 10% respectively of the whole venom toxic effect, were further analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), on-line liquid chromatography/electrospray mass spectrometry (LC/ESMS) and off-line LC/MALDI-TOFMS in order to establish their mass fingerprints. The molecular masses in fraction II were predominantly between 6500 and 7500 Da. This corresponds to long-chain toxins that mainly act on voltage-gated Na(+) channels. Fraction III is more complex and predominantly contained molecules with masses between 2500 and 5000 Da. This corresponds to the short-chain toxin family, most of which act on K(+) channels, and other unknown peptides. Finally, we were able to measure the molecular masses of 380 different compounds present in the two fractions investigated. To our knowledge, this is the largest number of components ever detected in the venom of a single animal species. Some of the toxins described previously from T. serrulatus venom could be detected by virtue of their molecular masses. The interpretation of this large set of data has provided us with useful proteomic information on the venom, and the implications of these findings are discussed.

A hyaluronidase from Tityus serrulatus scorpion venom: isolation, characterization and inhibition by flavonoids

The purification procedure of a hyaluronidase from Tityus serrulatus scorpion venom is described. It involves basically an ion-exchange chromatography on CM-cellulose at pH 7.8 followed by a rechromatography of the active fraction on the same column at pH 4.7. The optima pH and temperature for maximum activity of the isolated enzyme was 6.0 and 40°C, respectively. Its K M was 69.7 μg/ml at 37°C and its specific activity was 19,900±1,730 turbidity reducing units (TRU)/mg against 845±88 TRU/mg for the whole desiccated venom, representing a 23- to 24-fold purification range. The hyaluronidase activity of the purified protein (51 kDa) was inhibited by some flavonoid compounds. This article also showed that T. serrulatus hyaluronidase affected on the activity of the venom's major toxin, tityustoxin-I (TsTX-I or Ts1), as reflected by alterations in the serum levels of creatine kinase (CK), lactate dehydrogenase (LD) and aspartate aminotransferase (AST) following injection of TsTX-I, in the presence or absence of hyaluronidase.

MODIFICATION OF BIOLOGICAL PROPERTIES OF PROTEIN TOXINS BY STEPWISE IODINATION

By gradual incorporation of stable iodine into toxins and whole venoms it is possible to abolish completely the physiological, lesion and lethal properties of the native components. The properties of iodinated antigens and from antibodies generated by these detoxified derivatives, are presented. The hapten is incorporated into tyrosyl and histidyl residues. The derivatives can be obtained in less than one hour. Within the same batch of protein, there is a determinable stoichiometric ratio hapten/protein to achieve the desired modified properties of the derivative. The iodinating solutions are easy to prepare, can be accurately standardized and have unlimited shelf lives. The cost of the whole procedure is very low. No side-effects, local or systemic were observed, even with prolonged use of the derivatives. The method was applied to toxic components and whole venom of the scorpion Tityus serrulatus, and the hypertensive, bradipneic, oliguric, lesional, lethal and cytotoxic effects were completely abolished. Polyclonal antibodies generated by these iodinated antigens neutralized the virulent effects of native components and reversed the α effects of the whole venom in frog sciatic nerves. They conferred active immunization in mice, rats, guinea pigs, goats, horses and pigeons. Crotoxin and whole venom of Crotalus durrissus terrificus lost the lesional and lethal activity, but conserving the immunogenic capacity. They produced antibodies against the native components, giving also vaccinal protection. While the virulent crotalic antigens had a cytotoxic activity, the iodinated antigens were highly mitogenic with human white cells. Five bothropic venoms were neutralized in the hemorrhagic, tissue lesion and lethal capacity, the derivatives were immunogenic. Repetitive sublethal doses of scorpionic, crotalic and bothropic venoms lead invariably to an amyloid-like deposit in tissues, whereas the iodinated samples were ineffective. Allergenic extracts of Schistosoma mansoni can be transformed into anallergic derivatives that retains antigenic properties. Violently allergenic extracts of Ascaris lumbricoides suum can be completely deactivated with iodination, but conserved immunological competence. Cholera, tetanus and botulinum toxins, as iodinated toxoids, had its lesional and lethal capacity completely avoided. Physiological proteins with strong biological activity can also be rendered innocuous. Iodinated insulin lost its capacity to lower blood glucose levels, but induced high avidity antibodies in guinea-pigs and rabbits. By iodination, kallikrein can be turned unable to contract rat uterus, and to liberate kinins from kinninogen. Modified tonin do not increase the blood pressure in rats. Aqueous extracts of Leptospira canis and L. icterohaemorrhagiae after iodination, were innocuous to hatched eggs, and immunogenic in mice and rabbits. A lectin from Macrotylema axillare, lost the hemaglutination capacity with only 75% of iodine saturation. The derivative was highly immunogenic in rabbits. Heavy iodination can transform self-antigens in non-self, generating antibodies in same species animals. All derivatives obtained were stable, did not show any reversion to toxicity, generated antibodies against the native antigens and gave active protection when injected in animals. The injections were also apparently painless. The time gap between the accident and the administration of antibodies is discussed for systemic and local effects. A new schedule for immunization, only feasible with toxoided venoms is presented. It is based on a clonal expansion induced by a small dose, followed by an exponential saturation dose of the same toxoid. The attainment of higher levels of protecting antibodies against the native antigen in the generated sera, is unmatched by other procedures. Data for practical use of iodination is presented.

Sandwich-ELISA detection of venom antigens in envenoming by Phoneutria nigriventer spider

Enzyme linked immunosorbent assays (ELISA) were developed to detect antigens from Phoneutria nigriventer spider venom. Horse anti- P. nigriventer immunoglobulins were prepared by immunoaffinity chromatography and used to set up a sandwich-type ELISA. The specificity of the assay was demonstrated by its capacity to correctly discriminate between the circulating antigens in mice that were experimentally inoculated with P. nigriventer venom from those in mice inoculated with Lycosa sp. and Loxosceles intermedia spider venoms, Tityus serrulatus scorpion venom and Apis mellifera bee venom. Measurable absorbance signals were obtained with 0.8 ng of venom per assay. The ELISA was used to follow the kinetic distribution of antigens in experimentally envenomed mice and to detect antigens in the sera of patients envenomed by P. nigriventer.

Evidence for a direct action of Tityus serrulatus scorpion venom on the cardiac muscle

The ability of toxins to activate the cardiovascular system plays an important role in the morbidity and lethality of the Tityus serrulatus scorpion envenoming. Most of the actions of the scorpion toxins are indirect and due to the release of adrenergic and cholinergic neurotransmitters. Accordingly, treatment following envenoming is targeted towards inhibition of adrenergic and cholinergic receptors. Here, we have sought evidence for a direct action of T. serrulatus venom on the isolated rat heart (Langendorff's method). We show that the bradycardia induced by T. serrulatus venom was completely blocked by atropine, a muscarinic receptor antagonist. Similarly, the increase in heart rate that follows the venom-induced bradycardia was totally inhibited by a β1-adrenoceptor antagonist or by chemical sympathetic denervation with 6-hydroxydopamine. In contrast to these findings, the venom-induced increase in contractile force was not modified by β1-adrenoceptor blockade or by chemical sympathetic denervation. The results clearly demonstrate that the chronotropic effects of T. serrulatus are dependent on neurotransmitter release, but the inotropic effects are not. The neurotransmitter-independent increase in contractility seems to be a direct action of the venom on cardiomyocytes. We suggest that this direct effect on cardiac fibers may play a role in the development of cardiac arrhythmias and contractility defects following envenoming with T. serrulatus scorpion.

Molecular cloning and sequence analysis of cDNAs encoding a β-toxin-like peptide and two MkTx I homologues from scorpion Buthus martensii Karsch

Three full-length cDNAs, one encoding the precursor of a β-toxin-like peptide (named BmKBT) and the other two encoding those of (MkTx I) homologues (named MkTx II and MkTx III, respectively), were isolated from a venom gland cDNA library of the Chinese scorpion Buthus martensii Karsch, by screening with a cDNA fragment generated by PCR. The encoded precursor of BmKBT contained 83 amino acid residues including a signal peptide of 19 residues, a mature peptide of 63 residues and an extra basic residue (Lys) which have to be removed in the processing step. The deduced amino acid sequence of BmKBT showed 52% homology to that of β-neurotoxin TsVII isolated from scorpion Tityus serrulatus. However, the positions of disulfide bridges have a little variation between the two peptides. The precursors of MkTx II and MkTx III both contained 85 amino acid residues including a signal peptide of 19 residues, a mature peptide of 64 residues and two extra residues (Gly–Arg) which have to be removed in the processing step, too. There was high sequence similarity (90%) between the two peptides. The sequences of mature MkTx II and MkTx III were highly homologous with MkTx I isolated from scorpion Buthus martensii Karsch, both showing 90% identities.

Inhibition of gastric emptying and intestinal transit in anesthetized rats by a Tityus serrulatus scorpion toxin.

The effects of a fraction (T1) of Tityus serrulatus scorpion venom prepared by gel filtration on gastric emptying and small intestinal transit were investigated in male Wistar rats. Fasted animals were anesthetized with urethane, submitted to tracheal intubation and right jugular vein cannulation. Scorpion toxin (250 microg/kg) or saline was injected iv and 1 h later a bolus of saline (1.0 ml/100 g) labeled with 99m technetium-phytate (10 MBq) was administered by gavage. After 15 min, animals were sacrificed and the radioactivity remaining in the stomach was determined. Intestinal transit was evaluated by instillation of a technetium-labeled saline bolus (1.0 ml) through a cannula previously implanted in the duodenum. After 60 min, the progression of the marker throughout 7 consecutive gut segments was estimated by the geometric center method. Gastric retention of the liquid test meal in rats injected with scorpion toxin (median: 88%; range: 52-95%) was significantly higher (P<0.02) than in controls (54%; 21-76%), an effect which was not modified by gastric secretion blockade with ranitidine. The progression of the isotope marker throughout the small intestine was significantly slower (P<0.05) in rats treated with toxin (1.2; 1.0-2.5) than in control animals (2.3; 1.0-3.2). Inhibition of both gastric emptying and intestinal transit in rats injected with scorpion toxin suggests an increased resistance to aboral flow, which might be caused by abnormal neurotransmitter release or by the local effects of venom on smooth muscle cells.

Scorpion venom-induced neutrophilia is inhibited by a PAF receptor antagonist in the rat.

A dramatic blood neutrophilia is an important feature of the severe envenoming caused by the Brazilian scorpion Tityus serrulatus and may contribute to the development of lung injury in children. We examined the effects of an intravenous injection of T. serrulatus scorpion venom (TsV) on the total number of leukocytes and neutrophils in the blood of anesthetized rats. Injection of TsV (250 microg/kg) induces a significant leukocytosis 2 and 3 h after its injection, explained by an increase in the number of neutrophils. The release of catecholamines and action on adrenoceptors is responsible for most of the systemic manifestations of TsV. However, pretreatment with the beta-adrenoceptor antagonists metoprolol and propranolol or the alpha1-adrenoceptor antagonist prazosin (0.25 mg/kg) did not prevent TsV-induced neutrophilia. Blood neutrophilia induced by TsV occurred simultaneously with a significant reduction of mature neutrophils in bone marrow. Pretreatment with the platelet-activating factor (PAF) receptor antagonists UK-74505 or WEB-2086 prevented TsV-induced increase in blood neutrophils and reduction in the number of neutrophils in the bone marrow. It is concluded that scorpion venom induces blood neutrophilia in rats, explained by a PAF receptor-dependent mobilization of neutrophils from the bone marrow.

Crystal structure of the neurotoxin ts-γ from a venom of scorpion Tityus serrulatus at 1.73Å resolution

Crystal structure of the neurotoxin ts-γ from a venom of scorpion Tityus serrulatus at 1.73Å resolution

Neurotoxic Effects of Three Fractions Isolated from Tityus serrulatus Scorpion Venom

Abstract:Scorpion venoms contain low molecular weight basic polypeptides, neurotoxins, that are the principal toxic agents. These toxins act on ion channels, promoting a derangement that may result in an abnormal release of neurotransmitters. In the present study we investigated some of the effects of the F, H and J fractions isolated from Tityus serrulatus scorpion venom on the central nervous system of rodents. The venom was partially purified by gel filtration chromatography. The neurotoxic effect of these fractions was studied on convulsive activity after intravenous injection, and on electrographic activity and neuronal integrity of rat hippocampus when injected directly into this brain area. The results showed that intravenous injection of the F and H fractions induced convulsions, and intrahippocampal injection caused electrographic seizures in rats and neuronal damage in specific hippocampal areas. Fraction J injected intravenously reduced the general activity of mice in the open field but induced no changes when injected into the brain. These results suggest that scorpion toxins are able to act directly on the central nervous system promoting behavioural, electrographic and histological modifications.

Neurotoxic effects of three fractions isolated from Tityus serrulatus scorpion venom.

Scorpion venoms contain low molecular weight basic polypeptides, neurotoxins, that are the principal toxic agents. These toxins act on ion channels, promoting a derangement that may result in an abnormal release of neurotransmitters. In the present study we investigated some of the effects of the F, H and J fractions isolated from Tityus serrulatus scorpion venom on the central nervous system of rodents. The venom was partially purified by gel filtration chromatography. The neurotoxic effect of these fractions was studied on convulsive activity after intravenous injection, and on electrographic activity and neuronal integrity of rat hippocampus when injected directly into this brain area. The results showed that intravenous injection of the F and H fractions induced convulsions, and intrahippocampal injection caused electrographic seizures in rats and neuronal damage in specific hippocampal areas. Fraction J injected intravenously reduced the general activity of mice in the open field but induced no changes when injected into the brain. These results suggest that scorpion toxins are able to act directly on the central nervous system promoting behavioural, electrographic and histological modifications.

Acid-base balance following Tityus serrulatus scorpion envenoming in anaesthetized rats

In the present work the pH and arterial blood gases were measured in fasted and fed male albino rats, weighing 297±13 g, anaesthetized with urethane (1.4 g/kg, i.p.) before and after injection of T1 fraction from Tityus serrulatus scorpion venom, during 60 min. Arterial blood samples were collected at 0, 5, 15, 30 and 60 min for pH, pCO 2, pO 2, bicarbonate and base-excess analysis. The data showed that the scorpion toxin induced a continuous drop in the blood pH along the time. Hypercapnia and hypoxemia peaking at 30 min and followed by a recovery towards normal values at 60 min were also observed. A pronounced decrease in the blood bicarbonate levels at 60 min and negative base-excess values along with time were evident at 60 min. The comparisons between fasted and fed animals have shown that in the last group the effects of scorpion toxin on the arterial blood gases were less pronounced. We conclude that T1 fraction of Tityus serrulatus scorpion venom induces in anaesthetized rats an acute respiratory acidosis followed by metabolic acidosis.

A study on convulsions in mice induced by venom from the scorpion Tityus serrulatus Lutz &amp; Mello, 1922

A study on convulsions in mice induced by venom from the scorpion Tityus serrulatus Lutz &amp; Mello, 1922

Convulsive effects of some isolated venom fractions of the Tityus serrulatus scorpion: behavioral, electroencephalographic, and neuropathological aspects

It has been previously shown that the crude venom of Tityus serrulatus can cause convulsions. This study was designed to investigate the neurotoxic effects of B, C, G, and K fractions isolated from this venom. Intravenous injection of these fractions in mice (0.6 - 6.0 mg/kg body weight) showed that the C fraction is a potent convulsant and G fraction decreased the threshold for tonic hand limb extension elicited by transauricular electroshock. Unilateral injection of B, C, and K fractions, but not G fraction, into the hippocampus of rats (0.6 - 6.0 µg) caused electroencephalographic alterations consisting of spikes and epileptic discharges that began in the hippocampus and evolved to the cortex. The following motor signs were observed: movements of facial muscles, wet dog shake, immobility, myoclonus, wild-running with clonus, and in some cases, loss of postural control. Intrahippocampal injection of B, C, and K fraction, but not G fraction, caused neuronal loss at the injection site as well as in other hippocampal areas. The effect of these fractions on epileptiform activity and on neuronal loss was dose-dependent. The severity of the epileptiform activity in the ipsilateral hippocampus correlated with the severity of the neuronal loss. The electrographic, behavioral, and histological changes induced by B, C, and K fractions were similar to those obtained with other drugs that are commonly used to induce convulsion. The convulsant effects of the crude venom may be caused by the fractions studied in this work.

Induction of neutralizing antibodies against Tityus serrulatus toxins by immunization with a recombinant nontoxic protein

An immunogenic nontoxic protein (TsNTxP) was purified from the venom of the scorpion Tityus serrulatus (Ts). This peptide is composed of 63 amino acid residues with a high degree of structural homology with the toxins isolated from Ts. The nucleotide sequence of the gene that encodes TsNTxP was obtained and also showed a high degree of similarity with genes encoding Tityus toxins [Guatimosim, S.C.F., Prado, V.F., Diniz, C.R., Chávez-Olórtegui, C., Kalapothakis, E., 1999. Molecular cloning and genomic analysis of TsNTxP; an immunogenic protein from Tityus serrulatus scorpion venom. Toxicon 37, 507–517]. In the present study the TsNTxP gene was expressed in E. coli BL21DE 3 cells as a fusion protein with maltose-binding protein. The recombinant protein (TsNTxPrec) was purified by affinity chromatography and used as an immunogen in rabbits. The antigenic specificity of anti-TsNTxPrec antibodies was compared by an enzyme-linked immunosorbent assay using TsNTxP, TstFG50 (the fraction of Ts venom that represents most of the toxicity of the crude venom) and the crude venom, to coat microtitration plates. Anti-TsNTxPrec antibodies had a comparable high cross-reactivity for all antigens tested. Concentrations of Ts venom equivalent to 20 LD 50 were effectively neutralized by 1 ml of the anti-TsNTxPrec serum. This result provides basic data for the use of such recombinant scorpion protein as an immunogen in the development of antivenoms for clinical use.