Divergence in toxin antigenicity and venom enzymes in Tityus melici, a medically important scorpion, despite transcriptomic and phylogenetic affinities with problematic Brazilian species.

The Brazilian scorpion Tityus melici, native to Minas Gerais and Bahia, is morphologically related to Tityus serrulatus, the most medically significant species in Brazil. Despite inhabiting scorpion-envenomation endemic regions, T. melici venom remains unexplored. This work evaluates T. melici venom composition and function using transcriptomics, enzymatic activities, and in vivo and in vitro immunological analyses. Next-Generation Sequencing unveiled 86 components putatively involved in venom toxicity: 39 toxins, 28 metalloproteases, seven disulfide isomerases, six hyaluronidases, three phospholipases and three amidating enzymes. T. serrulatus showed the highest number of toxin matches with 80-100 % sequence similarity. T. melici is of medical importance as it has a venom LD50 of 0.85 mg/kg in mice. We demonstrated venom phospholipase A2 activity, and elevated hyaluronidase and metalloprotease activities compared to T. serrulatus, paralleling our transcriptomic findings. Comparison of transcriptional levels for T. serrulatus and T. melici venom metalloenzymes suggests species-specific expression patterns in Tityus. Despite close phylogenetic association with T. serrulatus inferred from COI sequences and toxin similarities, partial neutralization of T. melici venom toxicity was achieved when using the anti-T. serrulatus antivenom, implying antigenic divergence among their toxins. We suggest that the Brazilian therapeutic scorpion antivenom could be improved to effectively neutralize T. melici venom.

Production of recombinant scorpion antivenoms in E. coli: current state and perspectives.

Scorpion envenomation is a serious health problem in tropical and subtropical zones. The access to scorpion antivenom is sometimes limited in availability and specificity. The classical production process is cumbersome, from the hyper-immunization of the horses to the IgG digestion and purification of the F(ab)'2 antibody fragments. The production of recombinant antibody fragments in Escherichia coli is a popular trend due to the ability of this microbial host to produce correctly folded proteins. Small recombinant antibody fragments, such as single-chain variable fragments (scFv) and nanobodies (VHH), have been constructed to recognize and neutralize the neurotoxins responsible for the envenomation symptoms in humans. They are the focus of interest of the most recent studies and are proposed as potentially new generation of pharmaceuticals for their use in immunotherapy against scorpion stings of the Buthidae family. This literature review comprises the current status on the scorpion antivenom market and the analyses of cross-reactivity of commercial scorpion anti-serum against non-specific scorpion venoms. Recent studies on the production of new recombinant scFv and nanobodies will be presented, with a focus on the Androctonus and Centruroides scorpion species. Protein engineering-based technology could be the key to obtaining the next generation of therapeutics capable of neutralizing and cross-reacting against several types of scorpion venoms. KEY POINTS: • Commercial antivenoms consist of predominantly purified equine F(ab)'2fragments. • Nanobody-based antivenom can neutralize Androctonus venoms and have a low immunogenicity. • Affinity maturation and directed evolution are used to obtain potent scFv families against Centruroides scorpions.

Neutralization Capacity of Tissue Alterations Caused by the Venoms of the Most Dangerous Scorpions in North Africa Using a Selective Antivenom.

In North Africa, scorpion stings pose an urgent public health problem, particularly for children with high morbidity and mortality rates. The main species implicated are the Androctonus mauretanicus (Am), Androctonus australis hector (Aah), and Buthus occitanus (Bo). Immunotherapy is the specific therapeutic approach aimed at directly neutralizing toxins, despite their severity and rapid diffusion. In the present study, we evaluate, histologically and immunohistologically, the neutralization potency of the selective antivenom produced against, among other species, the Am, Aah, and Bo at the level of the tissue alterations in Swiss mice, as experimental subjects. Firstly, the lethal doses 50 test was conducted to assess the venom's toxic activity, and then the median effective dose of the antivenom was determined against each venom. The histological and immunohistological analyses were performed by injecting the sublethal dose of venom, the complex venom and antivenom, or the antivenom 2 h following inoculation of venom. Our study revealed the highest toxicity of the Am, followed by the Aah and then the Bo venom. The neutralizing ability and effectiveness of the antivenom to completely or partially neutralize the tissular damages were demonstrated in all organs studied: brain, heart, lungs, liver, and kidneys. Our results highlighted the important cytoplasmic and membranous staining in the heart compared to the brain tissue for the three scorpion venoms. Therefore, the scorpionic antivenoms are able to reach their target even at the tissue level. Immunotherapy represents the specific and recommended treatment against the scorpionic stings in North Africa.

Antivenoms, hepatitis B vaccine and oral polio vaccine can be considered for storage and handling outside the cold chain following the innovative 'controlled temperature chain' approach.

Possible applicability of controlled temperature chain (CTC) for selected antisera and vaccines was evaluated. Bivalent oral polio vaccine (OPV), hepatitis B vaccine (HepB vaccine; monovalent and combined) and antisera (lyophilized and liquid scorpion-antivenom and liquid snake-antivenom) were tested. Samples were stored at accelerated (35 ± 5 °C) and freezing (-25 ± 5 °C) conditions for 24 h, one week and one month in addition to recommended storage condition (2-8 °C), except OPV samples that were tested at accelerated and refrigerated (2-8 °C) conditions compared to recommended storage conditions (-25 ± 5 °C). All samples were tested for potency. Protein content and composition were determined for antisera samples. All vaccine vial-monitors were evaluated. HepB vaccine was subjected to aluminum-content assay, shake test and microscopical examination. No significant change in antisera potency was detectable under accelerated condition for a week. OPV stored in refrigerator for a month and at accelerated condition for 48 h maintained acceptable potency. Monovalent and combined HepB vaccine maintained acceptable potency under accelerated condition for a month and a week, respectively. Freezing adversely affected HepB vaccine. In conclusion, reevaluation of storage conditions of tested products is urgently required; this can reduce storage costs and improves their availability. Other products should be tested for possible CTC applicability.

In vitro laboratory analyses of commercial anti-scorpion (Mesobuthus tamulus) antivenoms reveal their quality and safety but the prevalence of a low proportion of venom-specific antibodies.

Mesobuthus tamulus (Indian Red Scorpion) sting is a severe but neglected health issue in India. The accomplishment of in-patient scorpion sting management is highly dependent on the safety, efficacy, and homogeneity of scorpion antivenom preparation. Therefore, in this study, the above qualities of commercial anti-scorpion antivenoms manufactured in India were assessed by in vitro laboratory analyses. Biophysical characterization of venom by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, size exclusion chromatography, and proteomics analysis demonstrated that anti-scorpion antivenoms (ASAs) mostly contain F(ab')2 molecules with a trace amount of undigested immunoglobulin (Ig) G. The physicochemical characterization, electron microscopy, and dynamic light scattering studies revealed that ASAs were prepared according to the guidelines of World Health Organization (WHO), and were devoid of aggregate content and virus particles. ASAs did not show IgE contamination and bacterial endotoxin but demonstrated moderate complement activation properties, which may have adverse effects in treated patients. Spectrofluorometric and atomic force microscopy analyses showed poor binding of venom with commercial ASAs. The percent of antibodies raised against the venom toxins in commercial ASAs was determined at the range of 5.3-6.3%, which is a reason for their poor efficacy. This study advocates the importance of in vitro laboratory analyses for assessing commercial antivenom's quality and safety parameters before their pre-clinical research and clinical use to treat Indian red scorpion sting.

Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the world's most diverse rainfores.

Venom from Amazonian scorpions of the genus Tityus contains components capable of eliciting a distinct clinical, mostly neurological, syndrome. This contrasts with the mainly autonomic manifestations produced after envenomation by congeneric southern and northern South American species. Herein, we summarize Pan-Amazonian scorpionism by synthesizing available toxinological, clinical, and molecular data gathered from all affected areas in Amazonia, including Brazil, Ecuador, Colombia, Peru, Venezuela, and French Guiana. We searched multiple databases, as well as our own records, for reports of scorpion envenomations in Amazonia by confirmed Tityus spp., and compared the clinical manifestations. To help uncover clinical and venom relationships among problematic species, we explored phylogenetic relationships with a rate-calibrated analysis of mitochondrial COI data from available species. The possible existence of diversity gradients for venom toxic and immunogenic components despite the predicted strong phylogenetic association among species is underscored by discussed clinical and toxinological findings. A multicentric effort, involving all nations affected by this neglected disease, is urgently needed to offer alternatives for treating and understanding this pathology, including the preparation of neutralizing antibodies with a broad range of efficacy.

Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the worlds most diverse rainfores

Abstract Venom from Amazonian scorpions of the genus Tityus contains components capable of eliciting a distinct clinical, mostly neurological, syndrome. This contrasts with the mainly autonomic manifestations produced after envenomation by congeneric southern and northern South American species. Herein, we summarize Pan-Amazonian scorpionism by synthesizing available toxinological, clinical, and molecular data gathered from all affected areas in Amazonia, including Brazil, Ecuador, Colombia, Peru, Venezuela, and French Guiana. We searched multiple databases, as well as our own records, for reports of scorpion envenomations in Amazonia by confirmed Tityus spp., and compared the clinical manifestations. To help uncover clinical and venom relationships among problematic species, we explored phylogenetic relationships with a rate-calibrated analysis of mitochondrial COI data from available species. The possible existence of diversity gradients for venom toxic and immunogenic components despite the predicted strong phylogenetic association among species is underscored by discussed clinical and toxinological findings. A multicentric effort, involving all nations affected by this neglected disease, is urgently needed to offer alternatives for treating and understanding this pathology, including the preparation of neutralizing antibodies with a broad range of efficacy.

Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the world's most diverse rainfores

Venom from Amazonian scorpions of the genus Tityus contains components capable of eliciting a distinct clinical, mostly neurological, syndrome. This contrasts with the mainly autonomic manifestations produced after envenomation by congeneric southern and northern South American species. Herein, we summarize Pan-Amazonian scorpionism by synthesizing available toxinological, clinical, and molecular data gathered from all affected areas in Amazonia, including Brazil, Ecuador, Colombia, Peru, Venezuela, and French Guiana. We searched multiple databases, as well as our own records, for reports of scorpion envenomations in Amazonia by confirmed Tityus spp., and compared the clinical manifestations. To help uncover clinical and venom relationships among problematic species, we explored phylogenetic relationships with a rate-calibrated analysis of mitochondrial COI data from available species. The possible existence of diversity gradients for venom toxic and immunogenic components despite the predicted strong phylogenetic association among species is underscored by discussed clinical and toxinological findings. A multicentric effort, involving all nations affected by this neglected disease, is urgently needed to offer alternatives for treating and understanding this pathology, including the preparation of neutralizing antibodies with a broad range of efficacy.(AU)

Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the world’s most diverse rainfores

Venom from Amazonian scorpions of the genus Tityus contains components capable of eliciting a distinct clinical, mostly neurological, syndrome. This contrasts with the mainly autonomic manifestations produced after envenomation by congeneric southern and northern South American species. Herein, we summarize Pan-Amazonian scorpionism by synthesizing available toxinological, clinical, and molecular data gathered from all affected areas in Amazonia, including Brazil, Ecuador, Colombia, Peru, Venezuela, and French Guiana. We searched multiple databases, as well as our own records, for reports of scorpion envenomations in Amazonia by confirmed Tityus spp., and compared the clinical manifestations. To help uncover clinical and venom relationships among problematic species, we explored phylogenetic relationships with a rate-calibrated analysis of mitochondrial COI data from available species. The possible existence of diversity gradients for venom toxic and immunogenic components despite the predicted strong phylogenetic association among species is underscored by discussed clinical and toxinological findings. A multicentric effort, involving all nations affected by this neglected disease, is urgently needed to offer alternatives for treating and understanding this pathology, including the preparation of neutralizing antibodies with a broad range of efficacy.

A randomized comparative study between intravenous and intramuscular scorpion antivenom regimens in children.

BACKGROUND: Scorpion envenomation and its consequences represented a serious healthcare problem in Upper Egypt and considered to be an important cause of life-threatening emergency particularly in children. METHODS: One hundred patients presented to the emergency department of Assiut University Children Hospital with a history of scorpion sting aged less than 18 years were included in our randomized comparative trial during 2016. Two groups of patients were randomly categorized according to the route of administration of scorpion antivenom; intramuscular and intravenous with 50 patients in each group. Full history, clinical examination, and routine baseline investigations were performed. RESULTS: Myocarditis, encephalopathy, cardiogenic shock, ICU admission, need for mechanical ventilation, mean hospital stay and mortality were significantly lower in those received intravenous antivenom compared with those received intramuscular one. CONCLUSION: The results of the present study and other experimental and clinical trials confirmed that the administration of the scorpion antivenom by intravenous route has a lower incidence of systemic toxicity, a better outcome of fatal complication resulted from envenomation especially cardiogenic shock, decreased need for ICU facilities and mechanical ventilation, shorter hospital stay, and better overall outcome than the intramuscular route. TRIAL REGISTRATION NUMBER: UMIN-CTR Study Design: trial number: UMIN000022032.

Escorpionismo. Registro de consultas médicas en el Centro Nacional de Intoxicaciones: período 2000-2010 / Scorpionism. Registration of medical consultations at the National Poison Center: Period 2000-2010

El escorpionismo es un envenenamiento de etiología accidental producido por la inoculación del veneno de un alacrán o escorpión, que ocurre predominantemente en áreas urbanas, en el ámbito domiciliario o peridomiciliario. En nuestro país son tres las especies de escorpiones de interés médico-sanitario: Tityus trivittatus, T. confluens y T. bahiensis. El cuadro clínico se caracteriza por presentar dolor agudo con escaso compromiso cutáneo y manifestaciones sistémicas que pueden, ocasionalmente, causar la muerte, principalmente en niños. El objetivo de esta publicación es, dar a conocer el registro de consultas en el Centro Nacional de Intoxicaciones en el período comprendido entre Enero de 2000 a Diciembre de 2010.

The scorpionism is an accidental poisoning produced by the inoculation of the venom of a scorpion, which in Argentina occurs predominantly in urban areas, in the domestic environment or around the human habitat. In our country there are three species of scorpions of medical-health concern: Tityus trivittatus, T. confluens and T. bahiensis. The clinical picture is characterized by severe pain with limited cutaneous and systemic manifestations, can occasionally include death, especially in children. The aim of this publication is to present the consultation in the National Poison Center in the period from January 2000 to December 2010.

Is scorpion antivenom cost-effective as marketed in the United States?

PURPOSE: The purpose of this study was to analyze the cost-effectiveness of scorpion antivenom compared to no antivenom, in the United States, using a decision analysis framework. METHODS: A decision analytic model was created to assess patient course with and without antivenom. Costs were determined from the perspective of a health care payer. Cost data used in the model were extracted from Arizona Medicaid. The probability of clinical events occurring with and without antivenom was obtained from the published literature, medical claims obtained from Arizona Medicaid, and results of recent clinical trials. Patients that became so ill that mechanical ventilator support was necessary were considered treatment failures. A Monte Carlo simulation was run 1000 times and sampled simultaneously across all variable distributions in the model. RESULTS: The mean success rate was 99.87% (95% CI 99.64%-99.98%) with scorpion antivenom and 94.31% (95% CI 91.10%-96.61%) without scorpion antivenom. The mean cost using scorpion antivenom was $10,708 (95% CI $10,556 - $11,010) and the mean cost without scorpion antivenom was $3178 (95% CI $1627 - $5184). Since the 95% CIs do not overlap for either the success or cost, use of the scorpion antivenom was significantly more effective and significantly more expensive than no antivenom. Cost-effectiveness analysis found that the scorpion antivenom was not cost-effective at its current price as marketed in the United States. CONCLUSION: The scorpion antivenom marketed in the United States is extremely effective, but too costly to justify its use in most clinical situations. Formulary committees should restrict the use of this antivenom to only the most severe scorpion envenomations.

Escorpionismo: presentación de un posible caso grave ocurrido en la Ciudad Autónoma de Buenos Aires / Scorpionism: presentation of a possible serious case occurred in Ciudad Autónoma de Buenos Aires

El escorpionismo, en su aspecto clínico es un envenenamiento de causa accidental producido por la inoculación del veneno de un alacrán o escorpión, que en Argentina ocurre predominantemente en áreas urbanas, en el ámbito domiciliario o peridomiciliario. En nuestro país son tres las especies de escorpiones de interés médico-sanitario: Tityus (T.) trivittatus, T. confluens y T. bahiensis. El cuadro clínico se caracteriza por presentar dolor agudo con escaso compromiso cutáneo y manifestaciones sistémicas que, sin tratamiento pueden provocar la muerte, principalmente en niños. El objetivo de esta comunicación es dar a conocer el primer caso de escorpionismo grave, ocurrido en la Ciudad Autónoma de Buenos Aires, en una niña de 4 años de edad y describir el cuadro clínico característico y la necesidad del tratamiento precoz en los casos moderados y severos.

Scorpionism in its clinical aspect is an envenoming caused by accidental sting and inoculation of venom from a scorpion, which in Argentina occurs predominantly in urban areas, in the home environment or peridomiciliary. In our country there are three species of scorpions of medical-health concern: Tityus (T.) trivittatus, T. confluens and T. bahiensis. The clinical picture is characterized by severe pain with limited cutaneous and systemic manifestations, that without treatment can cause death, especially in children. The aim of this communication is to present the first case of severe scorpionism occurred in the City of Buenos Aires, in a 4 years old girl, and to describe the characteristic clinical picture and the need for early treatment in moderate and severe cases of scorpionism.