Expression of Recombinant Stonustoxin Alpha Subunit and Preparation of polyclonal antiserum for Stonustoxin Neutralization Studies

Stonustoxin (SNTX) is a lethal protein found in stonefish venom, responsible for many of the symptoms associated with stonefish envenomation. To counter stonefish venom challenges, antivenom is a well-established and effective solution. In this study, we aimed to produce the recombinant alpha subunit protein of Stonustoxin from Synanceia horrida and prepare antibodies against it The SNTXα gene sequence was optimized for E. coli BL21 (DE3) expression and cloned into the pET17b vector. Following purification, the recombinant protein was subcutaneously injected into rabbits, and antibodies were extracted from rabbit´s serum using a G protein column As a result of codon optimization, the codon adaptation index for the SNTXα cassette increased to 0.94. SDS-PAGE analysis validated the expression of SNTXα, with a band observed at 73.5 kDa with a yield of 60 mg/l. ELISA results demonstrated rabbits antibody titers were detectable up to a 1:256,000 dilution. The isolated antibody from rabbit´s serum exhibited a concentration of 1.5 mg/ml, and its sensitivity allowed the detection of a minimum protein concentration of 9.7 ng. In the neutralization assay the purified antibody against SNTXα protected mice challenged with 2 LD50. In conclusion, our study successfully expressed the alpha subunit of Stonustoxin in a prokaryotic host, enabling the production of antibodies for potential use in developing stonefish antivenom.

Suspected stonefish envenomation in Queensland over eight years: a retrospective series

INTRODUCTION

Stonefish envenomation results in localized severe pain and swelling and systemic features, including vomiting, arrhythmia, pulmonary oedema, and possibly death. There are limited data regarding the effectiveness of the available antivenom. The aim of this series is to characterize presentations of patients with suspected stonefish envenomation and investigate treatment, including antivenom.

METHODS

This is a retrospective observational series of suspected stonefish envenomation as reported to the Queensland Poisons Information Centre or Princess Alexandra Hospital Clinical Toxicology Unit from July 2015 to January 2023. Patients were identified through the databases held by both the Centre and Unit, and data on clinical features and investigations were collected from the patient's electronic medical record.

RESULTS

There were 87 suspected stonefish envenomations from July 2015 to January 2023. The median age was 26 (range: 5-69) years, and 69 (79 per cent) patients were male. Pain was reported in 85 (98 per cent) with a median peak pain score of 10 (range 4-12; three rated their pain greater than 10/10). A clear wound was documented in 64 (74 per cent), with local swelling in 63 (72 per cent). A foreign body was retained in eight (9 per cent) presentations. Systemic symptoms were rare, with vomiting in four (5 per cent) and dizziness in two (2 per cent) presentations. There were no instances of hypotension, arrhythmia, or pulmonary oedema. Hot water was administered in 72 (83 per cent) presentations. Oral analgesia was given in 55 (63 per cent). Parenteral analgesia was given in 53 (61 per cent), most commonly opioids. Local anaesthetic block was performed in 19 presentations (22 per cent), with effectiveness documented in 16/19 (84 per cent). Five patients received antivenom for intractable pain, and all received subsequent parenteral analgesia or local anaesthetic block.

CONCLUSIONS

Stonefish envenomation is characterized by severe pain. Systemic symptoms were rare and not severe in this series. Local anaesthetic block appeared to be the most effective intervention for severe pain when performed. Antivenom appeared to be ineffective in managing pain.

Fish Cytolysins in All Their Complexity

The majority of the effects observed upon envenomation by scorpaenoid fish species can be reproduced by the cytolysins present in their venoms. Fish cytolysins are multifunctional proteins that elicit lethal, cytolytic, cardiovascular, inflammatory, nociceptive, and neuromuscular activities, representing a novel class of protein toxins. These large proteins (MW 150–320 kDa) are composed by two different subunits, termed α and β, with about 700 amino acid residues each, being usually active in oligomeric form. There is a high degree of similarity between the primary sequences of cytolysins from different fish species. This suggests these molecules share similar mechanisms of action, which, at least regarding the cytolytic activity, has been proved to involve pore formation. Although the remaining components of fish venoms have interesting biological activities, fish cytolysins stand out because of their multifunctional nature and their ability to reproduce the main events of envenomation on their own. Considerable knowledge about fish cytolysins has been accumulated over the years, although there remains much to be unveiled. In this review, we compiled and compared the current information on the biochemical aspects and pharmacological activities of fish cytolysins, going over their structures, activities, mechanisms of action, and perspectives for the future.

Clinical characteristics of stonefish "Oni-daruma-okoze" envenomation in Japan

Aim

Stonefish, known in Japan as "Oni-daruma-okoze" (Synanceia verrucosa Block et Schneider), inhabit the waters surrounding the Okinawa/Amami districts. By far, habubites have been limited to these areas mainly due to climatic conditions. Due to changes promoted by global warming and increasing tourism, concerns regarding the potential for stonefish envenomation as well as jellyfish stings on the main island of Japan are increasing. However, few studies of stonefish envenomation have been reported in Japan. The current study aimed to comprehensively examine for the first time the clinical characteristics of stonefish envenomation in Japan.

Methods

We administered retrospective questionnaire surveys between January 2013 and December 2017 to determine patient characteristics, treatment, and clinical outcomes of stonefish envenomation. We compared patient characteristics between tourists and non-tourists.

Results

Over the 5-year study period, 15 patients were identified from four hospitals. More than 70% of stonefish envenomation cases occurred in the northern part of Okinawa Main Island. All patients recovered well, including four patients with severe stonefish envenomation. In two severe cases, the length of hospitalization was more than 1 week (8-9 days). Antivenom was not given. There were no significant differences between tourists and non-tourists with regard to baseline characteristics.

Conclusions

During a 5-year period, 15 cases of stonefish envenomation occurred in Japan. The patients recovered well without treatment with antivenom.

The venoms of the lesser (Echiichthys vipera) and greater (Trachinus draco) weever fish- A review

In comparison with other animal venoms, fish venoms remain relatively understudied. This is especially true for that of the lesser Echiichthys vipera and greater weever fish Trachinus draco which, apart from the isolation of their unique venom cytolysins, trachinine and dracotoxin, respectively, remain relatively uncharacterised. Envenomation reports mainly include mild symptoms consisting of nociception and inflammation. However, like most fish venoms, if the venom becomes systemic it causes cardiorespiratory and blood pressure changes. Although T. draco venom has not been studied since the 1990's, recent studies on E. vipera venom have discovered novel cytotoxic components on human cancer cells, but due to the scarcity of research on the molecular make-up of the venom, the molecule(s) causing this cytotoxicity remains unknown. This review analyses past studies on E. vipera and T. draco venom, the methods used in the , the venom constituents characterised, the reported symptoms of envenomation and compares these findings with those from other venomous Scorpaeniformes.

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Research on the weever fish venoms Echiichthys vipera and Trachinus draco has

been scarce.

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E. vipera and T. draco venoms elicit cardiorespiratory symptoms in victims.

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E. vipera and T. draco contain unique cytolysins – Trachinine and Dracotoxin.

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Dracotoxin is haemolytic and contains membrane depolarising activities.

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E. vipera venom triggers apoptosis in human colon carcinoma cells.

The Cardiovascular and Neurotoxic Effects of the Venoms of Six Bony and Cartilaginous Fish Species

Fish venoms are often poorly studied, in part due to the difficulty in obtaining, extracting, and storing them. In this study, we characterize the cardiovascular and neurotoxic effects of the venoms from the following six species of fish: the cartilaginous stingrays Neotrygon kuhlii and Himantura toshi, and the bony fish Platycephalus fucus, Girella tricuspidata, Mugil cephalus, and Dentex tumifrons. All venoms (10–100 µg/kg, i.v.), except G. tricuspidata and P. fuscus, induced a biphasic response on mean arterial pressure (MAP) in the anesthetised rat. P. fucus venom exhibited a hypotensive response, while venom from G. tricuspidata displayed a single depressor response. All venoms induced cardiovascular collapse at 200 µg/kg, i.v. The in vitro neurotoxic effects of venom were examined using the chick biventer cervicis nerve-muscle (CBCNM) preparation. N. kuhlii, H. toshi, and P. fucus venoms caused concentration-dependent inhibition of indirect twitches in the CBCNM preparation. These three venoms also inhibited responses to exogenous acetylcholine (ACh) and carbachol (CCh), but not potassium chloride (KCl), indicating a post-synaptic mode of action. Venom from G. tricuspidata, M. cephalus, and D. tumifrons had no significant effect on indirect twitches or agonist responses in the CBCNM. Our results demonstrate that envenoming by these species of fish may result in moderate cardiovascular and/or neurotoxic effects. Future studies aimed at identifying the molecules responsible for these effects could uncover potentially novel lead compounds for future pharmaceuticals, in addition to generating new knowledge about the evolutionary relationships between venomous animals.

A review on the Scorpaena plumieri fish venom and its bioactive compounds

The most poisonous fish species found along the Brazilian coast is the spotted scorpionfish Scorpaena plumieri. Though hardly ever life-threatening to humans, envenomation by S. plumieri can be quite hazardous, provoking extreme pain and imposing significant socioeconomic costs, as the victims may require days to weeks to recover from their injuries. In this review we will walk the reader through the biological features that distinguish this species as well as the current epidemiological knowledge related to the envenomation and its consequences. But above all, we will discuss the challenges involved in the biochemical characterization of the S. plumieri venom and its compounds, focusing then on the successful isolation and pharmacological analysis of some of the bioactive molecules responsible for the effects observed upon envenomation as well as on experimental models. Despite the achievement of considerable progress, much remains to be done, particularly in relation to the non-proteinaceous components of the venom. Therefore, further studies are necessary in order to provide a more complete picture of the venom’s chemical composition and physiological effects. Given that fish venoms remain considerably less studied when compared to terrestrial venoms, the exploration of their full potential opens a myriad of possibilities for the development of new drug leads and tools for elucidating the complex physiological processes.