Zebrafish as Versatile Model for Assessing Animal Venoms and Toxins: Current Applications and Future Prospects

Animal venoms and toxins hold promise as sources of novel drug candidates, therapeutic agents, and biomolecules. To fully harness their potential, it is crucial to develop reliable testing methods that provide a comprehensive understanding of their effects and mechanisms of action. However, traditional rodent assays encounter difficulties in mimicking venom-induced effects in human due to the impractical venom dosage levels. The search for reliable testing methods has led to the emergence of zebrafish (Danio rerio) as a versatile model organism for evaluating animal venoms and toxins. Zebrafish possess genetic similarities to humans, rapid development, transparency, and amenability to high-throughput assays, making it ideal for assessing the effects of animal venoms and toxins. This review highlights unique attributes of zebrafish and explores their applications in studying venom- and toxin-induced effects from various species, including snakes, jellyfish, cuttlefish, anemones, spiders, and cone snails. Through zebrafish-based research, intricate physiological responses, developmental alterations, and potential therapeutic interventions induced by venoms are revealed. Novel techniques such as CRISPR/Cas9 gene editing, optogenetics, and high-throughput screening hold great promise for advancing venom research. As zebrafish-based insights converge with findings from other models, the comprehensive understanding of venom-induced effects continues to expand, guiding the development of targeted interventions and promoting both scientific knowledge and practical applications.

STRETCH: Stinging tree exposures to Cairns Hospital

OBJECTIVES

To evaluate the burden of disease, investigate the treatment and response to treatment caused by exposure to stinging tree plants presenting to Cairns Hospital over a 3-year period. Our secondary aim was to examine the benefit from treating such exposures with topical dilute hydrochloric acid (HCl).

METHODS

A retrospective chart review of all patients presenting to Cairns ED over a 3-year period because of stinging tree exposure. Symptoms, signs, treatment and outcomes were recorded.

RESULTS

There were 48 presentations, all having immediate pain after contact with the stinging tree, with 87% describing the pain as moderate or severe. Nearly all were stung on limbs (96%). There were 13 different treatments prior to presentation. In hospital, 60% needed opioid analgesia and a median oral morphine dose equivalent of 15 mg. Of the 29 receiving HCl nine patients reported good relief or complete relief.

CONCLUSIONS

Stinging tree exposure results in significant presentations to the Cairns ED each year. Pain is immediate and severe and there are no clear first aid or definitive treatment recommendations. Further work is needed to ascertain the best first aid and definitive treatment including a formal trial of dilute HCl.

On the Biological Diversity of Ant Alkaloids

Ants have outstanding capacity to mediate inter- and intraspecific interactions by producing structurally diverse metabolites from numerous secretory glands. Since Murray Blum's pioneering studies dating from the 1950s, there has been a growing interest in arthropod toxins as natural products. Over a dozen different alkaloid classes have been reported from approximately 40 ant genera in five subfamilies, with peak diversity within the Myrmicinae tribe Solenopsidini. Most ant alkaloids function as venom, but some derive from other glands with alternative functions. They are used in defense (e.g., alarm, repellants) or offense (e.g., toxins) but also serve as antimicrobials and pheromones. We provide an overview of ant alkaloid diversity and function with an evolutionary perspective. We conclude that more directed integrative research is needed. We suggest that comparative phylogenetics will illuminate compound diversification, while molecular approaches will elucidate genetic origins. Biological context, informed by natural history, remains critical not only for research about focal species, but also to guide applied research.

Molecular Characterization and Functional Analysis of the Nattectin-like Toxin from the Venomous Fish Thalassophryne maculosa

TmC4-47.2 is a toxin with myotoxic activity found in the venom of Thalassophryne maculosa, a venomous fish commonly found in Latin America whose envenomation produces an injury characterized by delayed neutrophil migration, production of major pro-inflammatory cytokines, and necrosis at the wound site, as well as a specific systemic immune response. However, there are few studies on the protein structure and functions associated with it. Here, the toxin was identified from the crude venom by chromatography and protein purification systems. TmC4-47.2 shows high homology with the Nattectin from Thalassophryne nattereri venom, with 6 cysteines and QPD domain for binding to galactose. We confirm its hemagglutinating and microbicide abilities independent of carbohydrate binding, supporting its classification as a nattectin-like lectin. After performing the characterization of TmC4-47.2, we verified its ability to induce an increase in the rolling and adherence of leukocytes in cremaster post-capillary venules dependent on the α5β1 integrin. Finally, we could observe the inflammatory activity of TmC4-47.2 through the production of IL-6 and eotaxin in the peritoneal cavity with sustained recruitment of eosinophils and neutrophils up to 24 h. Together, our study characterized a nattectin-like protein from T. maculosa, pointing to its role as a molecule involved in the carbohydrate-independent agglutination response and modulation of eosinophilic and neutrophilic inflammation.

Unusual Sting by a Nonindigenous Caterpillar in Europe

On the French island of Corsica, a 57-y-old woman without significant medical history was stung on the left thumb while she was taking care of an ornamental Ficus benjamina plant. Immediately, she felt intense pain in her hand. She saw a strange caterpillar, later identified by the local poison center as Acharia stimulea. The pain in her hand was evaluated as 8 of 10 using the numerical pain rating scale; only a slight erythema was visible on her skin. Symptoms disappeared within 2 h with use of local anti-inflammatory ointment and oral painkillers. Three other caterpillars emerged out of the soil of the potted plant during the following week. This sting by a saddleback caterpillar is exceptional in Corsica. French garden store owners and healthcare professionals should be informed that caterpillars can be imported across the oceans to Europe on different plants.

KAMBÔ: an Amazonian enigma

The secretions of the Giant Monkey Frog Phyllomedusa bicolor are used by populations in the Amazon regions (mainly the indigenous Katukinas and Kaxinawás). The so-called "toad vaccine" or "kambô" is applied as a medication for infections and to prevent diseases, and also as physical and mental invigorator, and analgesic. Since the 1980s, researchers and companies have been interested in the composition of these secretions. Phyllomedusin, phyllokinin, caerulein and sauvagine are the polypeptides in these secretions that can cause intense effects on smooth muscles, vessels provoking, nausea and vomiting, arterial hypotension, flushing, palpitations, nausea, vomiting, bile secretion and angioedema. These actions are similar to bradykinin. However, the feeling of well-being and improvement of motor skills described by the users seems to be associated with dermorphine, caerulein or deltorphin - peptides with analgesic properties - and their affinity for the opiate receptor systems. Caerulein is a peptide that increases digestive secretions. Phyllomedusin and Phyllokinin lead to blood pressure and digestive effects. Sauvagine release corticotropin and mimics the physiological reactions of exposure to stress. Deltorphins and dermorphins have high affinity for the opiate receptor system and can lead to analgesia. The fame acquired by the therapy motivated the use by individuals from urban areas worldwide, without safety considerations. While in indigenous communities, there is an entire cultural tradition that provides relative safety to the application, however, the extension of use to individuals from urban areas worldwide is a problem, with reports of severe adverse effects and deaths. Undoubtedly, the skin secretions of the Phyllomedusa genus contain substances of intense pharmacological action and that can lead to research for therapeutic uses, but control over their application in rituals outside the forest is needed due the risks presented.

Cottonmouth snake bites reported to the ToxIC North American snakebite registry 2013-2017

Introduction: The majority of venomous snake exposures in the United States are due to snakes from the subfamily Crotalinae (pit vipers). There are three types of US pit vipers: rattlesnakes (Crotalus and Sisturus spp.) copperheads (Agkistrodon contortrix), and cottonmouths (Agkistrodon piscivorus) also known as water moccasins. Cottonmouth bites are reported less frequently than other pit viper envenomations, and data on cottonmouth envenomation are limited. Our objective was to describe the epidemiology, clinical manifestations, and management of cottonmouth envenomations using prospective data reported to the Toxicology Investigators Consortium's (ToxIC) North American Snakebite Registry (NASBR)Methods: Cottonmouth envenomation cases reported to NASBR for the period from January 1, 2013, through December 31, 2017 were reviewed. Variables collected included patient demographics, bite location, clinical manifestations, and management.Results: Thirty-one cottonmouth envenomations were reported. Most bites occurred in children aged 7-12 (39%). Most bites involved the lower extremity (72%). Intentional interaction with the snake occurred in three cases (10%). Swelling was the most reported clinical effect and occurred in all patients. Gastrointestinal symptoms were reported in 19% of patients, and 19% developed coagulopathy. Antivenom treatment was used in 84% of patients. Nineteen patients (61%) required hospital stays of >24 hours.Discussion: Our study represents the first systematic prospective data collection on cottonmouth bites. Our data demonstrate that cottonmouth envenomations cause primarily local effects and, occasionally, systemic toxicity. Our study also demonstrates that antivenom is often indicated for these envenomations per published guidelines and recommendations.Conclusions: Cottonmouth envenomations are relatively infrequent. However, they can cause significant local and systemic toxicity. Most cottonmouth envenomations in this series were treated with antivenom and were hospitalized beyond 24 hours.

Friends or Foes? Emerging Impacts of Biological Toxins

Toxins are substances produced from biological sources (e.g., animal, plants, microorganisms) that have deleterious effects on a living organism. Despite the obvious health concerns of being exposed to toxins, they are having substantial positive impacts in a number of industrial sectors. Several toxin-derived products are approved for clinical, veterinary, or agrochemical uses. This review sets out the case for toxins as 'friends' that are providing the basis of novel medicines, insecticides, and even nucleic acid sequencing technologies. We also discuss emerging toxins ('foes') that are becoming increasingly prevalent in a range of contexts through climate change and the globalisation of food supply chains and that ultimately pose a risk to health.

Basics of Antibody Phage Display Technology

Antibody discovery has become increasingly important in almost all areas of modern medicine. Different antibody discovery approaches exist, but one that has gained increasing interest in the field of toxinology and antivenom research is phage display technology. In this review, the lifecycle of the M13 phage and the basics of phage display technology are presented together with important factors influencing the success rates of phage display experiments. Moreover, the pros and cons of different antigen display methods and the use of naïve versus immunized phage display antibody libraries is discussed, and selected examples from the field of antivenom research are highlighted. This review thus provides in-depth knowledge on the principles and use of phage display technology with a special focus on discovery of antibodies that target animal toxins.

Clinical and epidemiological profile of patients with severe H1N1/09 pandemic influenza in Australia and New Zealand: an observational cohort study

Background Pandemic influenza H1N1/09 emerged in April 2009 and spread widely in Australia and New Zealand. Although an unprecedented number of cases required intensive care, comparative community-based studies with seasonal influenza strains have not shown any significant differences in clinical symptoms or severity. Methods The authors performed active surveillance on confirmed influenza-related admissions and compared the clinical profile of patients with pandemic H1N1/09 influenza and patients with seasonal influenza at eight hospitals in Australia and one hospital in New Zealand. Results During the 1 July and 30 November 2009, 560 patients with confirmed influenza were admitted, of which 478 had H1N1/09, and 82 had other seasonal strains. Patients with H1N1/09 influenza were younger, were more likely to have fever and were more likely to be pregnant but less likely to have chronic obstructive pulmonary disease and ischaemic heart disease than patients with seasonal strains. Other clinical features and comorbidities were reported in similar proportions. Admission to intensive care was required in 22% of patients with H1N1/09 influenza and 12% in patients with other strains. Hospital mortality was 5% in patients with H1N1 influenza. Conclusions The clinical features of H1N1/09 influenza and seasonal strains were similar in hospitalised patients. A higher proportion of patients had comorbidities than had been reported in community-based studies. Although the overall mortality was similar, the authors found evidence that H1N1/09 caused severe disease in a higher proportion of hospitalised patients.