RESUMO

In this study, we report the innovative application of whole-cell patch-clamp electrophysiology in assessing broad-spectrum neutralisation by three different antivenoms, of venoms from the medically significant scorpion genus Centruroides. Envenomations by as many as 21 species from the Centruroides genus result in up to 300,000 envenomations per year in Mexico, which poses significant and potentially life-threatening pathophysiology. We first evaluated the in vitro manifestation of envenomation against two human voltage-gated sodium (hNaV) channel subtypes: hNaV1.4 and hNaV1.5, which are primarily expressed in skeletal muscles and cardiomyocytes, respectively. The neutralisation of venom activity was then characterised for three different antivenoms using a direct competition model against the more potent target, hNaV1.4. While broad-spectrum neutralisation was identified, variation in neutralisation arose for Centruroides elegans, C. limpidus, C. noxius and C. suffusus venoms, despite the presence of a number of these venoms within the immunising mixture. This raises questions regarding the truly "broad" neutralisation capacity of the antivenoms. This study not only extends previous validation of the in vitro investigation of antivenom efficacy utilising the whole-cell patch-clamp technique but also underscores the potential of this animal-free model in exploring cross-reactivity, experimental scalability, and most importantly, informing clinical management practices regarding the administration of antivenom in Mexico.

Assuntos

Antivenenos , Venenos de Escorpião , Escorpiões , Animais , Venenos de Escorpião/toxicidade , Antivenenos/farmacologia , Humanos , Picadas de Escorpião/tratamento farmacológico , Técnicas de Patch-Clamp , Especificidade da Espécie , México , Animais Peçonhentos

RESUMO

Alternative recombinant sources of antivenoms have been successfully generated. The application of such strategies requires the characterization of the venoms for the development of specific neutralizing molecules against the toxic components. Five toxic peptides to mammals from the Mexican scorpion Centruroides villegasi were isolated by chromatographic procedures by means of gel filtration on Sephadex G-50, followed by ion-exchange columns on carboxy-methyl-cellulose (CMC) resins and finally purified by high-performance chromatography (HPLC) columns. Their primary structures were determined by Edman degradation. They contain 66 amino acids and are maintained well packed by four disulfide bridges, with molecular mass from 7511.3 to 7750.1 Da. They are all relatively toxic and deadly to mice and show high sequence identity with known peptides that are specific modifiers of the gating mechanisms of Na+ ion channels of type beta-toxin (ß-ScTx). They were named Cv1 to Cv5 and used to test their recognition by single-chain variable fragments (scFv) of antibodies, using surface plasmon resonance. Three different scFvs generated in our laboratory (10FG2, HV, LR) were tested for recognizing the various new peptides described here, paving the way for the development of a novel type of scorpion antivenom.

Assuntos

Peptídeos , Venenos de Escorpião , Escorpiões , Anticorpos de Cadeia Única , Animais , Venenos de Escorpião/química , Venenos de Escorpião/toxicidade , Venenos de Escorpião/imunologia , Peptídeos/química , Anticorpos de Cadeia Única/química , Humanos , Camundongos , Sequência de Aminoácidos , Antivenenos/imunologia , Antivenenos/química , Antivenenos/farmacologia , Animais Peçonhentos

RESUMO

This study analyzed a total of 260 confirmed scorpion stings reported in the city of Manaus, in the Brazilian Amazon, from 1990 to 2020. Cases were mapped according to the GPS location of their occurrence and plotted on a satellite image of the city. The stings generally occurred close to green areas, and the hotspots of stings moved north as city grew into that direction over time. Spatial analysis shows that scorpion stings mostly occur in poor, recently urbanized areas. The rapid and unplanned urbanization of originally forested areas, without offering adequate infrastructure and services, creates favorable conditions for infestation by scorpions and increases the risk of scorpion stings.

Assuntos

Picadas de Escorpião , Escorpiões , Urbanização , Brasil/epidemiologia , Picadas de Escorpião/epidemiologia , Humanos , Animais , Cidades , Masculino , Adulto , Feminino , Criança , Adolescente , Pessoa de Meia-Idade , Adulto Jovem , Pré-Escolar

RESUMO

The Tityus trinitatis, a black scorpion species endemic to the fauna of Trinidad, has been implicated in envenomation with devastating clinical sequelae such as acute pancreatitis and major adverse cardiovascular events. We present the first in-Caribbean case of a 59-year-old Caribbean South Asian male with human immunodeficiency virus who presented with a non-ST-segment-elevation acute coronary syndrome after being stung, which was managed with comprehensive, guideline-directed medical therapy. The clinician should be cognizant of scorpion-induced acute coronary syndrome (ACS) as a potential sequela of envenomation and its clinical management.

Assuntos

Síndrome Coronariana Aguda , Picadas de Escorpião , Humanos , Masculino , Síndrome Coronariana Aguda/induzido quimicamente , Síndrome Coronariana Aguda/etiologia , Pessoa de Meia-Idade , Picadas de Escorpião/complicações , Picadas de Escorpião/tratamento farmacológico , Animais , Eletrocardiografia , Escorpiões , Trinidad e Tobago

RESUMO

Studies on the interaction sites of peptide toxins and ion channels typically involve site-directed mutations in toxins. However, natural mutant toxins exist among them, offering insights into how the evolutionary process has conserved crucial sequences for activities and molecular target selection. In this study, we present a comparative investigation using electrophysiological approaches and computational analysis between two alpha toxins from evolutionarily close scorpion species of the genus Tityus, namely, Tst3 and Ts3 from T. stigmurus and T. serrulatus, respectively. These toxins exhibit three natural substitutions near the C-terminal region, which is directly involved in the interaction between alpha toxins and Nav channels. Additionally, we characterized the activity of the Tst3 toxin on Nav1.1-Nav1.7 channels. The three natural changes between the toxins did not alter sensitivity to Nav1.4, maintaining similar intensities regarding their ability to alter opening probabilities, delay fast inactivation, and induce persistent currents. Computational analysis demonstrated a preference for the down conformation of VSD4 and a shift in the conformational equilibrium towards this state. This illustrates that the sequence of these toxins retained the necessary information, even with alterations in the interaction site region. Through electrophysiological and computational analyses, screening of the Tst3 toxin on sodium isoform revealed its classification as a classic α-NaTx with a broad spectrum of activity. It effectively delays fast inactivation across all tested isoforms. Structural analysis of molecular energetics at the interface of the VSD4-Tst3 complex further confirmed this effect.

Assuntos

Venenos de Escorpião , Escorpiões , Venenos de Escorpião/química , Venenos de Escorpião/genética , Animais , Brasil , Humanos , Xenopus laevis , Ativação do Canal Iônico/efeitos dos fármacos , Sequência de Aminoácidos , Animais Peçonhentos

RESUMO

The impact of Covid-19 on envenomations by venomous animals in countries heavily affected by both conditions has not been quantified yet. Brazil shows high incidence of envenomations by scorpions, spiders and snakes and was heavily affected by waves of Covid-19. To determine how the pandemic impacted the epidemiology of envenomations by those three groups of venomous animals, we used online databases from two surveillance sources on number of cases and mortality. During the years before and during the pandemic, scorpion stings typically occurred in adults of both sexes in urban zones in the Southeast and Northeast regions. Spider bites occurred mainly in the South region, in adults of both sexes in urban zone. Snakebites affected mainly rural adult men in the Amazon. Between 2007 and 2021, overall incidence of cases by scorpions, spiders and snakes decreased after the beginning of the pandemic, snakebites did not show changes after the pandemic started in Brazil, but cases by scorpions and spiders decreased. No changes in the incidence of deaths were observed. On national level, Covid-19 affected some demographic, clinical and epidemiological aspects in cases by scorpions, spiders and snakes.

Assuntos

COVID-19 , Picadas de Escorpião , Mordeduras de Serpentes , Brasil/epidemiologia , COVID-19/epidemiologia , Humanos , Mordeduras de Serpentes/epidemiologia , Animais , Masculino , Feminino , Adulto , Incidência , Picadas de Escorpião/epidemiologia , Picada de Aranha/epidemiologia , Pessoa de Meia-Idade , Adolescente , Adulto Jovem , Criança , SARS-CoV-2 , Escorpiões , Serpentes , Pandemias , Idoso

RESUMO

INTRODUCTION: Scorpionism is a public health problem, especially in tropical regions. In Brazil, the prevalence of envenomation by scorpions is high, and the average national lethality is around 0.16 percent. The Tityus serrulatus scorpion is the primary species of medical importance. However, objective tools to predict and define the severity of these envenomations are lacking. MATERIALS AND METHODS: This was an observational study conducted among patients aged 0-19 years with scorpionism. Patients were admitted to a reference hospital between December 2020 and May 2022. Point-of-care ultrasound was performed within 24 hours of the scorpion sting. RESULTS: Forty-nine patients were included, with a median age of 3.6 (interquartile range 2.3-5.3) years and a predominance of females (51 percent). Fifteen patients (30.6 percent) presented major life-threatening signs, 32 (65.3 percent) minor systemic manifestations, and two (4.1 percent) only local manifestations. Left ventricular dysfunction was identified in 13 patients (26.5 percent). Ten patients (20.4 percent) presented pattern B (visualization of three or more B lines in the evaluated quadrant) in at least one lung window. The sensitivity and specificity of cardiac and pulmonary ultrasound to identify the most severely ill patients were 86 percent and 94 percent, respectively. DISCUSSION: The changes found on point-of-care ultrasound were associated with life-threatening signs. All patients with class III envenomation were referred to the intensive care unit, showing the importance of early identification of this subgroup. The main limitations were the small sample size and the fact that admission to intensive care was not based on systematic criteria. CONCLUSIONS: Point-of-care ultrasound is able to identify early signs of pulmonary congestion and heart failure in scorpionism. It can be useful for the objective selection of patients who are at a higher risk of complications and death and who require intensive support; it may also be valuable for periodic reassessments. Point-of-care ultrasound is a valuable tool for identifying and monitoring severe cases of scorpionism.

Assuntos

Sistemas Automatizados de Assistência Junto ao Leito , Picadas de Escorpião , Índice de Gravidade de Doença , Ultrassonografia , Humanos , Feminino , Masculino , Pré-Escolar , Criança , Lactente , Adolescente , Brasil/epidemiologia , Adulto Jovem , Escorpiões , Hospitalização , Animais

RESUMO

This study comprehensively analyzed cases of scorpion envenomation in Brazil, exploring the temporal trends and geographic patterns of such incidents between January 1, 2012, and December 31, 2022. Simultaneously, we assessed the correlation between scorpion envenomation and social determinants of health and social vulnerability. We conducted a population-based ecological study, gathering information on the number of scorpion envenomation cases in Brazil, as well as socioeconomic data and social vulnerability indicators across the 5,570 Brazilian municipalities. The season-trend model, based on the classical additive decomposition method, informed estimations of scorpion envenomation variations over time. The spatial correlation of scorpion envenomation with socioeconomic and vulnerability indicators was assessed using the Bivariate Moran's I. A total of 1,343,224 cases of scorpion envenomation were recorded in Brazil from Jan 2012 to Dec 2022. A single increasing time trend was observed for the entire country for this period (APC 8.94, P < 0.001). The seasonal analysis was significant for Brazil as a whole and all regions (p < 0.001), with peaks evident between October and November. The spatial distribution of cases was heterogeneous, with spatial clusters concentrated in the high-risk Southeast and Northeast regions. There was a high incidence of scorpion envenomation in municipalities facing social vulnerability, and, paradoxically, in those with better sanitation and waste collection. Our study revealed a heterogeneous geographical distribution of scorpion accidents in Brazil. Municipalities with higher social vulnerability exhibited a high incidence of scorpion envenomation.

Assuntos

Picadas de Escorpião , Determinantes Sociais da Saúde , Humanos , Brasil/epidemiologia , Picadas de Escorpião/epidemiologia , Cidades , Condições Sociais

RESUMO

Five peptides were isolated from the venom of the Mexican scorpion Centruroides bonito by chromatographic procedures (molecular weight sieving, ion exchange columns, and HPLC) and were denoted Cbo1 to Cbo5. The first four peptides contain 66 amino acid residues and the last one contains 65 amino acids, stabilized by four disulfide bonds, with a molecular weight spanning from about 7.5 to 7.8 kDa. Four of them are toxic to mice, and their function on human Na+ channels expressed in HEK and CHO cells was verified. One of them (Cbo5) did not show any physiological effects. The ones toxic to mice showed that they are modifiers of the gating mechanism of the channels and belong to the beta type scorpion toxin (ß-ScTx), affecting mainly the Nav1.6 channels. A phylogenetic tree analysis of their sequences confirmed the high degree of amino acid similarities with other known bona fide ß-ScTx. The envenomation caused by this venom in mice is treated by using commercially horse antivenom available in Mexico. The potential neutralization of the toxic components was evaluated by means of surface plasmon resonance using four antibody fragments (10FG2, HV, LR, and 11F) which have been developed by our group. These antitoxins are antibody fragments of single-chain antibody type, expressed in E. coli and capable of recognizing Cbo1 to Cbo4 toxins to various degrees.

Assuntos

Animais Peçonhentos , Perciformes , Peçonhas , Humanos , Cricetinae , Animais , Cavalos , Camundongos , Escorpiões , Cricetulus , Escherichia coli , Filogenia , Antivenenos , Aminoácidos , Fragmentos de Imunoglobulinas , Peptídeos

RESUMO

Background: In Colombia, several species of Buthidae scorpions belonging to the genera Centruroides and Tityus coexist, and their stings are considered life-threatening to humans because of their venom neurotoxins. Despite previous studies focusing on neurotoxins from these scorpion genera, little is known about the enzymes present in their venoms and their relationship with whole venom toxicity. Methods: Here, using proteomic and biochemical protocols the enzymatic activities of the venoms of three Colombian scorpion species, C. margaritatus, T. pachyurus, and T. n. sp. aff. metuendus, were compared to establish the presence and absence of enzymes such as phospholipases, hyaluronidases, and proteases that could be related to venom toxicity. Results: C. margaritatus was positive for hyaluronidases, T. n. sp. aff. metuendus for proteases, and T. pachyurus exhibited activity for all three mentioned enzymes. Conclusion: This information provides valuable insights into the specific enzyme diversity of each species' venom and their potential role in venom toxicity, which could contribute to the development of better treatments and prevention strategies for scorpion envenomation.