Search Results (83)

Botulinum neurotoxins (BoNTs), produced by the anaerobic spore-forming bacterium Clostridium botulinum, are among the most potent known biological toxins. BoNTs cause lethal botulism via contaminated food, wound infections, or infant intestinal colonization, posing significant threats to public health. Although the mouse bioassay is still being considered as the gold standard for detecting BoNTs, its drawbacks, including the lengthy experimental duration, high costs, and ethical issues, highlight the urgent need to develop alternative methods to fulfill the detection requirements. In recent years, frequent botulism poisoning incidents haves put forward higher requirements for detection technology. On-site detection is expected to be rapid and immediate, while laboratory detection requires high sensitivity and serotype discrimination capabilities. This review comprehensively introduces current detection approaches, including mouse bioassay, cell-based assays, immunological methods, endopeptidase–mass spectrometry, biosensors, chromatography, and mass spectrometry techniques. Notably, cell-based assays have been used for the potency testing of commercialized botulinum toxin type A and are considered the most promising alternative to the mouse bioassay. Biosensors based on nanomaterials demonstrate advantages in real-time detection due to their rapid response and portability, while endopeptidase–mass spectrometry achieves high sensitivity and effective serotype identification by specifically recognizing toxin-cleaved substrates. Future works shall aim to completely replace MBA, developing a detection system suitable for multiple scenarios such as clinical diagnosis, food safety monitoring, and environmental monitoring. The detection methods should also have matrix compatibility and serotype discrimination capabilities. Full article

Paralytic shellfish poisoning toxins (PSPTs) are a class of neurotoxins most known for causing illness from consuming contaminated shellfish. These toxins are also present in freshwater systems with the concern that they contaminate drinking and recreational waters. This review provides (1) a complete list of the 84+ known PSPTs and important chemical features; (2) a complete list of all environmental freshwater PSPT detections; (3) an outline of the certified PSPT methods and their inherent weaknesses; and (4) a discussion of PSPT toxicology, the weaknesses in existing data, and existing freshwater regulatory limits. We show ample evidence of production of freshwater PSPTs by cyanobacteria worldwide, but data and method uncertainties limit a proper risk assessment. One impediment is the poor understanding of freshwater PSPT profiles and lack of commercially available standards needed to identify and quantify freshwater PSPTs. Further constraints are the limitations of toxicological data derived from human and animal model exposures. Unassessed mouse toxicity data from 1978 allowed us to calculate and propose toxicity equivalency factors (TEF) for 11-hydroxysaxitoxin (11-OH STX; M2) and 11-OH dcSTX (dcM2). TEFs for the 11-OH STX epimers were calculated to be 0.4 and 0.6 for 11α-OH STX (M2α) and 11β-OH STX (M2β), while we estimate that TEFs for 11α-OH dcSTX (dcM2α) and 11β-OH dcSTX (dcM2β) congeners would be 0.16 and 0.23, respectively. Future needs for freshwater PSPTs include increasing the number of reference materials for environmental detection and toxicity evaluation, developing a better understanding of PSPT profiles and important environmental drivers, incorporating safety factors into exposure guidelines, and evaluating the accuracy of the established no-observed-adverse-effect level. Full article

Tetrodotoxin (TTX), earlier known as a tropical paralytic neurotoxin from pufferfish poisoning, has increasingly been occurring in edible marine species, including filter-feeding bivalves, from relatively cold marine waters of some European countries. The defined conditions that promote the production of TTX, its origin or the processes of its accumulation in seafood are still not clarified. Recent studies in temperate waters show, however, that the accumulation of quantifiable levels of TTX in bivalves appears to be influenced by seawater temperature (>15 °C), which indicates a seasonal occurrence at these latitudes. Uncertainties still remain regarding how seawater temperature interacts with other climate and environmental factors or organisms in the marine ecosystem to result in detectable levels of TTX in shellfish. Knowledge of the occurrence and distribution of TTX in the marine environment where the edible bivalves grow is important for maintaining seafood safety, as the toxin is heat-stable and remains potent even after cooking. Therefore, in this study, 264 bivalve samples collected in 2019 and 2021 from 17 sites along the Swedish west coast were analyzed with LC-MS/MS to search for TTX. The study explores the hypothesis of TTX presence in Swedish marine waters, outlines the sample screening strategy and objectives, and reports no evidence of TTX presence in Swedish bivalve shellfish (≥7.8 µg/kg) based on the analyzed samples and the time periods in which the studied samples were collected. Full article

The marine diatoms Pseudo-nitzschia spp. are globally distributed primary producers, with certain species capable of producing neurotoxin domoic acid (DA), causing amnesic shellfish poisoning (ASP). This study investigates the toxicity and growth rates of Pseudo-nitzschia species isolated from aquaculture areas in the Central Adriatic Sea. A total of 54 strains from eight species were analysed, with strains originating from four different study sites. Growth rates and toxin production were examined across different growth phases in other species and strains. Most species, including P. allochrona, P. calliantha, P. delicatissima, P. fraudulenta, P. galaxiae, P. mannii, and P. multistriata, did not produce DA at any growth phase. The only species that showed toxin production, at 18 °C was P. pseudodelicatissima (0.0007–0.0250 pg cell⁻¹). Notably, the majority of P. pseudodelicatissima strains were toxic in the decay phase and some strains showed continuous toxin production throughout all growth phases. The highest growth rates for the analysed species were recorded in strains of P. delicatissima, which also exhibited the highest cell abundance (8.19 × 10⁵ cell mL⁻¹), followed by the species P. allochrona, P. mannii and P. pseudodelicatissima. Full article

Butter clams (Saxidomus gigantea) are a staple in the subsistence diets of Alaskan Native communities and are also harvested recreationally. This filter–feeding species can accumulate saxitoxins (STXs), potent neurotoxins produced by late spring and summer blooms of the microalga Alexandrium catenella. The consumption of tainted clams can cause paralytic shellfish poisoning (PSP). Traditional beliefs and early reports on the efficacy of removing clam siphons have created the impression that cleaning butter clams by removing certain tissues makes them safe to eat. However, the toxin distribution within clams can vary over time, making the practice of cleaning butter clams unreliable. This study tested the effectiveness of the cleaning methods practiced by harvesters on Kodiak Island, Alaska. Specifically, butter clams were cleaned by removing different tissues to produce samples of “edible” tissues that were tested for STX content. The results were compared to historical data from a study conducted in Southeast Alaska from 1948 to 1949. Using these data, the risk for an average–sized man and woman consuming 200 g of edible tissue was calculated. The results showed that for clams containing >200 µg STX–equivalents 100 g edible tissue⁻¹, no cleaning method reduced the concentration of STXs in the remaining tissue below the regulatory limit. Meals containing >900 µg STX–equivalents 100 g edible tissue⁻¹ posed a substantial risk of moderate or severe symptoms. No cleaning method assured that untested butter clams are safe to eat. Full article

Tetrodotoxin (TTX) is a potent marine neurotoxin found in pufferfish, causing severe poisoning or death if consumed improperly. Studies have indicated that intestinal symbiotic microbiota are associated with the production and accumulation of TTX in pufferfish. However, the specific symbiotic microorganisms involved in these processes and their respective functions remain unclear. This study explored differences in intestinal microbiota related to the TTX content between toxic and non-toxic tiger puffer Takifugu rubripes. We found that the dominant phyla exhibiting significant abundance differences between the two groups were Proteobacteria and Bacteroidota, with the core bacterial genera being Rikenella, Vibrio, Photobacterium, and Bacteroides. Moreover, the genera Marinimicrobium, Idomarina, Galbibacter, and Brumimicrobium were reported for the first time to be potentially associated with TTX bioaccumulation in T. rubripes. In addition, an integrated analysis with our previous study indicated that the “ABC transporters” pathway may play significant roles in the production and transport of TTX in both symbiotic microorganisms and T. rubripes. This study preliminarily investigated the intestinal symbiotic bacteria associated with the accumulation and metabolism of TTX in T. rubripes, as well as screening potential microbial biomarkers for assessing the safety of pufferfish. Full article

Background: Three aconitine poisoning events occurred in two Canadian provinces in 2022: one in British Columbia (BC) and two in Ontario (ON). Aconitine is a potent alkaloid found in several species of the plant Aconitum, containing cardiotoxins and neurotoxins. It is used in traditional Chinese medicine (TCM) for pain management, and in powdered form, Aconitum is similar in appearance to sand ginger (Kaempferia galanga), which can lead to poisonings from misidentification and mislabeling. Methods: Aconitine poisoning is rare in Canada; here, we compare communications, collaborations, laboratory testing options and actions during investigations. Results: Fourteen cases occurred from the consumption of sand ginger: in BC (n = 2), purchased at an Asian health food store; in ON (n = 11), Kaempferia galanga powder (KGP) spices were used to prepare meals at a restaurant, and in one ON case, KGP was purchased. Traceback found product imported from China contained aconitine levels ranging from 1304 to 5500 ppm. Later investigations revealed mislabeling of Aconitum as KGP from the same imported lot (January 2020). Plant DNA testing found no KGP in any spice packets, including lots not linked to illness, suggestive of adulteration. Conclusion: Method development for aconitine in BC led to an improved response time for testing in ON. BC and ON updated outbreak response protocols and communications. Full article

Botulinum neurotoxins are synthetized by anaerobic, spore-forming bacteria that inhibit acetylcholine release at the level of the neuromuscular and autonomic cholinergic junctions, thus inducing a series of symptoms, the most relevant of which is flaccid paralysis. At least seven serotypes and over 40 subtypes are known, and they are among the most poisonous natural substances. There are different forms of botulism according to the route of contamination, but the clinical manifestation of descending symmetric flaccid paralysis is consistent, regardless of the route of contamination. It is very severe and potentially lethal. The induced paralysis lasts as long as the toxin is active, with variable length, according to the serotype of the toxin. This transient activity, as well as the precise mechanism of action, are the basis for the rationale behind use of the toxin in therapy for several clinical conditions, particularly, spastic conditions, as well as chronic migraine and axillary hyperhidrosis. The toxin has also been approved for the reduction in facial wrinkles; all these clinical applications, coupled with the toxin’s risks, have earned botulinum the title of a two-faced Janus protein. No approved vaccines are currently available, andthe only approved antidotes are the human specific intravenous immunoglobulins for infant botulism and the heptavalent equine immunoglobulins/(F(ab’)² for adults. Nanobodies, which show great promise, may penetrate neuronal cells to inactivate the toxin within the cytoplasm, and Ebselen, a non-toxic, economic, small-molecule inhibitor, has the characteristic of inhibiting the toxin irrespective of the serotype. Full article

Tetrodotoxin (TTX) is a neurotoxin that binds to sodium channels and blocks sodium conduction. Importantly, TTX has been increasingly detected in edible aquatic organisms. Because of this and the lack of specific antidotes, TTX poisoning is now a major threat to public health. However, it is of note that ultra-low dose TTX is an excellent analgesic with great medicinal value. These contradictory effects highlight the need for further research to elucidate the impacts and functional mechanisms of TTX. This review summarizes the latest research progress in relation to TTX sources, analogs, mechanisms of action, detection methods, poisoning symptoms, therapeutic options, biosynthesis pathways, and mechanisms of transport and accumulation in pufferfish. This review also provides a theoretical basis for reducing the poisoning risks associated with TTX and for establishing an effective system for its use and management to ensure the safety of fisheries and human health. Full article

Paraquat (1,1′-dimethyl-4,4′-bipyridilium dichloride), a widely used bipyridinium herbicide, is known for inducing oxidative stress, leading to extensive cellular toxicity, particularly in the lungs, liver, kidneys, and central nervous system (CNS), and is implicated in fatal poisonings. Due to its biochemical similarities with the neurotoxin 1-methyl-4-phenylpyridinium (MPP+), paraquat has been used as a Parkinson’s disease model, although its broader neurotoxic effects suggest the participation of multiple mechanisms. Demyelinating diseases are conditions characterized by damage to the myelin sheath of neurons. They affect the CNS and peripheral nervous system (PNS), resulting in diverse clinical manifestations. In recent years, growing concerns have emerged about the impact of chronic, low-level exposure to herbicides on human health, particularly due to agricultural runoff contaminating drinking water sources and their presence in food. Studies indicate that paraquat may significantly impact myelinating cells, myelin-related gene expression, myelin structure, and cause neuroinflammation, potentially contributing to demyelination. Therefore, demyelination may represent another mechanism of neurotoxicity associated with paraquat, which requires further investigation. This manuscript reviews the potential association between paraquat and demyelination. Understanding this link is crucial for enhancing strategies to minimize exposure and preserve public health. Full article

Brevetoxins (PbTxs) are very potent marine neurotoxins that can cause an illness clinically described as neurologic shellfish poisoning (NSP). These toxins are cyclic polyether in chemistry and have increased their geographical distribution in the past 2 decades. However, the ethical problems as well as technical difficulties associated with currently employed analysis methods for marine toxins have spurred the quest for suitable alternatives to be applied in a regulatory monitoring regime. In this work, we reported the first instance of concurrent aptamer selection of Brevetoxin-1 (PbTx-1) and Brevetoxin-2 (PbTx-2) and constructed a biolayer interferometry (BLI) biosensor utilizing PbTx-1 aptamer as a specific recognition element. Through an in vitro selection process, we have, for the first time, successfully selected DNA aptamers with high affinity and specificity to PbTx-1 and PbTx-2 from a vast pool of random sequences. Among the selected aptamers, aptamer A5 exhibited the strongest binding affinity to PbTx-1, with an equilibrium dissociation constant (K_D) of 2.56 μM. Subsequently, we optimized aptamer A5 by truncation to obtain the core sequence (A5-S3). Further refinement was achieved through mutations based on the predictions of a QGRS mapper, resulting in aptamer A5-S3G, which showed a significant increase in the K_D value by approximately 100-fold. Utilizing aptamer A5-S3G, we fabricated a label-free, real-time optical BLI aptasensor for the detection of PbTx-1. This aptasensor displayed a broad detection range from 100 nM to 4000 nM PbTx-1, with a linear range between 100 nM and 2000 nM, and a limit of detection (LOD) as low as 4.5 nM. Importantly, the aptasensor showed no cross-reactivity to PbTx-2 or other marine toxins, indicating a high level of specificity for PbTx-1. Moreover, the aptasensor exhibited excellent reproducibility and stability when applied for the detection of PbTx-1 in spiked shellfish samples. We strongly believe that this innovative aptasensor offers a promising alternative to traditional immunological methods for the specific and reliable detection of PbTx-1. Full article

Paralytic shellfish toxins (PSTs) are potent neurotoxins produced by certain microalgae, particularly dinoflagellates, and they can accumulate in shellfish in coastal seawater and thus pose significant health risks to humans. To explore the relationship between toxicity and PST profiles in seawater and mussels, the spatiotemporal variations in PST concentrations and profiles were investigated along the southern coast of Korea under peak PST levels during spring. Seawater and mussel samples were collected biweekly from multiple stations, and the toxin concentrations in the samples were measured. Moreover, the dinoflagellate community composition was analyzed using next-generation sequencing to identify potential PST-producing species. The PST concentrations and toxin profiles showed substantial spatiotemporal variability, with GTX1 and GTX4 representing the dominant toxins in both samples, and C1/2 tending to be higher in seawater. Alexandrium species were identified as the primary sources of PSTs. Environmental factors such as water temperature and salinity influenced PST production. This study demonstrates that variability in the amount and composition of PSTs is due to intricate ecological interactions. To mitigate shellfish poisoning, continuous monitoring must be conducted to gain a deeper understanding of these interactions. Full article

Botulism is one of the most serious food intoxications, manifesting as prolonged paralytic conditions. This disease is usually the result of the consumption of poor quality canned or smoked foods, so the inhabitants of many countries of the world are exposed to the risk of this kind of poisoning every year. In view of the severity of poisonings caused by botulinum neurotoxins, monoclonal antibodies (mAbs) show great promise because of their targeting action, lack of allergic reactions and serum sickness. The use of a cocktail of mAbs increases the “functional specificity” of their mixture, allowing them to bind to the active domains of different toxin chains and block their action. In this work, we obtained 14 murine mAbs to the catalytic and receptor-binding domain of botulinum toxin type A. The Sp2/0-Ag14 murine myeloma cell line and splenocytes from immunized mice of the BALB/c line were used as fusion partners. We have shown that the selected cocktail of three antibodies neutralizes native toxin more effectively than antibodies separately—complete neutralization is achieved at a toxin dose of 3LD50 and partial neutralization at 5LD50. We presume that this cocktail may be promising as a prototype for the creation of a therapeutic drug capable of neutralizing the toxin in the blood of patients. Full article

Kodo millet, a staple food in North India, is frequently consumed, but its consumption can lead to intoxication and poisoning. Kodo millet is a rich source of nutrition, with anti-oxidant and medicinal properties, and is typically cultivated in dry and semi-arid regions. It is often infected by fungal species rather than bacterial and virus pathogens, causing economic crop loss and adversely affecting grain and fodder yield. Ergot, a parasitic fungal endophyte found in Kodo millet ear heads, can cause poisoning when consumed. Moreover, Kodo millet grains are frequently infested with Aspergillus tamarii Kita, which produces a significant amount of the mycotoxin cyclopiazonic acid (CPA). Cyclopiazonic acid (CPA) is a neurotoxin produced by certain A. flavus and Aspergillus oryzae strains, which produce aflatoxins. Mycotoxicosis outbreaks in humans are not well characterized, and the direct correlation between mycotoxin consumption and toxic effects In Vivo is not well established. CPA, a specific inhibitor of sarcoplasmic reticulum Ca²⁺-ATPase, can adversely affect broiler chicken health, as demonstrated by toxicological evaluation of aflatoxins and CPA alone or in combination. Most toxins have reported acute and chronic effects in prokaryotic and eukaryotic systems, including humans, despite thefact that their specific modes of action are unclear. This review explores fungal pathogens, the toxicity of CPA to animals and humans, both by itself and in combination with other mycotoxins, as well as biocontrol strategies and storage methods for better utilization of Kodo grains post harvest. Full article

Ciguatoxins (CTXs) are neurotoxins responsible for ciguatera poisoning (CP), which affects more than 50,000 people worldwide annually. The development of analytical methods to prevent CP is a pressing global issue, and the N2a assay is one of the most promising methods for detecting CTXs. CTXs are highly toxic, and an action level of 0.01 μg CTX1B equivalent (eq)/kg in fish has been proposed. It is desirable to further increase the detection sensitivity of CTXs in the N2a assay to detect such low concentrations reliably. The opening of voltage-gated sodium channels (Na_V channels) and blocking of voltage-gated potassium channels (K_V channels) are thought to be involved in the toxicity of CTXs. Therefore, in this study, we developed an assay that could detect CTXs with higher sensitivity than conventional N2a assays, using K_V channel inhibitors as sensitizing reagents for N2a cells. The addition of the K_V channel inhibitors 4-aminopyridine and tetraethylammonium chloride to N2a cells, in addition to the traditional sensitizing reagents ouabain and veratridine, increased the sensitivity of N2a cells to CTXs by up to approximately 4-fold. This is also the first study to demonstrate the influence of K_V channels on the toxicity of CTXs in a cell-based assay. Full article