Pathogenicity and virulence of Clostridium botulinum

Development and characterization of a novel neutralizing scFv vectored immunoprophylaxis against botulinum toxin type A

Botulinum toxin is a protein toxin secreted by Clostridium botulinum that is strongly neurotoxic. Due to its characteristics of being super toxic, quick acting, and difficult to prevent, the currently reported antiviral studies focusing on monoclonal antibodies have limited effectiveness. Therefore, for the sake of effectively prevention and treatment of botulism and to maintain country biosecurity as well as the health of the population, in this study, we intend to establish a single chain antibody (scFv) targeting the carboxyl terminal binding functional domain of the botulinum neurotoxin heavy chain (BONT/AHc) of botulinum neurotoxin type A, and explore the value of a new passive immune method in antiviral research which based on adeno-associated virus (AAV) mediated vector immunoprophylaxis (VIP) strategy. The scFv small-molecular single-chain antibody sequenced, designed, constructed, expressed and purified by hybridoma has high neutralising activity and affinity level, which can lay a good foundation for the modification and development of antibody engineering drugs. In vivo experiments, AAV-mediated scFv engineering drug has good anti-BONT/A toxin neutralisation ability, has advantages of simple operation, stable expression and good efficacy, and may be one of the effective treatment strategies for long-term prevention and protection of BONT/A botulinum neurotoxin.

Tirbanibulin (KX2-391) analog KX2-361 inhibits botulinum neurotoxin serotype A mediated SNAP-25 cleavage in pre- and post-intoxication models in cells

Botulinum neurotoxins (BoNT) inhibit neuroexocytosis, leading to the potentially lethal disease botulism. BoNT serotype A is responsible for most human botulism cases, and there are no approved therapeutics to treat already intoxicated patients. A growing body of research has demonstrated that BoNT/A can escape into the central nervous system, and therefore, identification of BoNT/A inhibitors that can penetrate BBB and neutralize the toxin within intoxicated neurons would be important. We previously identified an FDA-approved, orally bioavailable compound, KX2-391 (Tirbanibulin) that inhibits BoNT/A in motor neuron assays. Recently, a structural analog of KX2-391, KX2-361, has been shown to exhibit good oral bioavailability and cross BBB with high efficiency in mouse experiments. Therefore, in this work, we evaluated the inhibitory effects of KX2-361 against BoNT/A. Toward this goal, we first evaluated the compound for its effects on cell viability in PC12 cells, via MTT assay, and in mouse embryonic stem cell (mESC)-derived motor neurons, with imaging-based assays. Following, we tested KX2-361 in mESC-derived motor neurons intoxicated with BoNT/A holotoxin, and the compound exhibited activity against the toxin in both pre- and post-intoxication conditions. Excitingly, KX2-361 also inhibited BoNT/A enzymatic component (light chain; LC) in PC12 cells transfected with BoNT/A LC. Furthermore, our molecular docking analyses suggested that KX2-361 can directly bind to BoNT/A LC. Medicinal chemistry approaches to develop structural analogs of KX2-361 to increase its efficacy against BoNT/A may provide a critical lead compound with BBB penetration capacity for drug development efforts against BoNT/A intoxication.

Comprehensive analysis of predominant pathogenic bacteria and viruses in seafood products

Given the growing global demand for seafood, it is imperative to conduct a comprehensive study on the prevalence and persistence patterns of pathogenic bacteria and viruses associated with specific seafood varieties. This assessment thoroughly examines the safety of seafood products, considering the diverse processing methods employed in the industry. The importance of understanding the behavior of foodborne pathogens, such as Salmonella typhimurium, Vibrio parahaemolyticus, Clostridium botulinum, Listeria monocytogenes, human norovirus, and hepatitis A virus, is emphasized by recent cases of gastroenteritis outbreaks linked to contaminated seafood. This analysis examines outbreaks linked to seafood in the United States and globally, with a particular emphasis on the health concerns posed by pathogenic bacteria and viruses to consumers. Ensuring the safety of seafood is crucial since it directly relates to consumer preferences on sustainability, food safety, provenance, and availability. The review focuses on assessing the frequency, growth, and durability of infections that arise during the processing of seafood. It utilizes next-generation sequencing to identify the bacteria responsible for these illnesses. Additionally, it analyzes methods for preventing and intervening of infections while also considering the forthcoming challenges in ensuring the microbiological safety of seafood products. This evaluation emphasizes the significance of the seafood processing industry in promptly responding to evolving consumer preferences by offering current information on seafood hazards and future consumption patterns. To ensure the continuous safety and sustainable future of seafood products, it is crucial to identify and address possible threats.

The First Reported Foodborne Botulism Outbreak in Riyadh, Saudi Arabia: Lessons Learned

BACKGROUND

Botulism has not been previously reported in the Kingdom of Saudi Arabia. This rare and sometimes fatal foodborne illness is caused by neurotoxins and primarily results from consuming home-canned fruits, vegetables, dairy, and seafood products & it can lead to paralysis.

OBJECTIVE

The purpose of this study was to evaluate the clinical features of patients who developed botulism in Riyadh in 2024 after consuming mayonnaise from a well-known local chain of restaurants in Riyadh, Saudi Arabia.

METHODS

We conducted a retrospective analysis of medical records and interviewed patients or their attendants for all hospitalized cases of foodborne botulism at Riyadh First Health Cluster. For each patient, a standard case report form was completed, containing information on demographics, clinical aspects, botulinum test results, and type of exposure. Descriptive statistics were applied to assess the data. During the outbreak, nineteen patients with foodborne diseases were admitted to Riyadh First Health Cluster Hospitals. Following thorough physical examinations, botulism was suspected in each case.

RESULTS

Eight of the 19 suspected foodborne illness patients fully satisfied the botulism case definition requirements set forth by the Saudi Arabian Public Health Authority (Weqaya). Among these eight patients, 2 (25%) were male and 6 (75%) were female, with a mean age of 23.25 ± 9.29 years (range: 12-38 years). The incubation period for our patients was 36.25 ± 26.26 h. Notable symptoms included dysphagia in all eight patients (100%), dysarthria, generalized weakness, nausea and vomiting in seven patients (88%), diplopia in four patients (50%), and stomach discomfort in three patients (38%). Of the eight cases, six required intubation, one mimicked brain death, and two were stable. The presence of Clostridium botulinum spores as the cause of the outbreak was confirmed by detecting botulinum spores in contaminated food.

CONCLUSION

Diplopia and dysarthria were the most common early sign of botulism. Early manifestations may include respiratory symptoms without any musculoskeletal symptoms. or nausea, vomiting and disorientation.

The Potential of Chicken-Herb Essence to Improve Milk Production and Infant Health in the Sprague Dawley Animal Model

Breast milk serves as the primary source of nourishment for newborns. In cases of low milk production, one approach to address this challenge involves the consumption of lactagogues. Chicken-herb essence, a beverage rich in protein, amino acids, and minerals, presents itself as a viable option to supplement a lactating mother's diet, particularly in terms of protein intake. This study aimed to evaluate the effects of chicken-herb essence on prolactin and lactoferrin in lactating rats. Furthermore, the study also assessed the lactagogue effect on IgA in offspring. The experimental research method used a completely randomized design. The animal models in this study were female Sprague Dawley rats. The result showed that there was an increase in milk production, as seen from the results of the lactagogue effect. The highest increase in prolactin and lactoferrin was obtained in treatment group II (TG II). The increases in prolactin and lactoferrin of TG II were 214.18 ± 71.99 and 904.02 ± 435.35 pg/mL, respectively. The lactagogue test showed that TG II haspotency as a milk-booster. Testing the blood serum of offspring showed that the highest concentration of IgA was also found in TG II at 398.34 ± 214.85 pg/mL.

Well-Established and Traditional Use of Vegetal Extracts as an Approach to the "Deep Roots" of Cough

Cough is a common presenting symptom for patients in a primary care setting and significantly impacts a patient's quality of life. Cough involves a complex reflex arc beginning with the stimulation of sensory nerves that function as cough receptors that stimulate the cough center in the brain. This "cough center" functions to receive these impulses and produce a cough by activating efferent nervous pathways to the diaphragm and laryngeal, thoracic, and abdominal musculature. Drugs that suppress the neural activity of cough are non-specific as those treatments are not directed toward pathogenic causes such as inflammation and oxidative stress. Moreover, they block a reflex called the watchdog of the lung and have a defense mechanism. Acute respiratory infections of the upper and lower airways most commonly cause acute cough. In contrast, the most common causes of chronic cough are upper airway cough syndrome, asthma, and gastroesophageal reflux disease, all associated with an inflammatory reaction at the level of the cough receptors. The use of natural compounds or herbal drugs such as carob syrup, dry blackcurrant extract, dry extract of caraway fruit, dry extract of ginger rhizome, dry extract of marshmallow root, and dry extract of ivy leaves, to name a few, not only have anti-inflammatory and antioxidant activity, but also act as antimicrobials, bronchial muscle relaxants, and increase gastric motility and empty. For these reasons, these natural substances are widely used to control cough at its deep roots (i.e., contrasting its causes and not inhibiting the arch reflex). With this approach, the lung watchdog is not put to sleep, as with peripheral or central inhibition of the cough reflex, and by contrasting the causes, we may control cough that viruses use at self-advantage to increase transmission.

Botulism Cases in Romania-An Overview of 14-Year National Surveillance Data

Botulism is a priority disease worldwide because it has a very severe course of evolution that can lead to death. This paper aims to describe the main epidemiological characteristics of botulism cases confirmed in Romania over 14 years (2007-2020). We performed a retrospective study using the publicly available national surveillance data and reported to the National Institute of Public Health. A total of 325 cases of foodborne botulism were reported in Romania, with no infant or wound botulism. Most of the cases (125, 38.5%) were reported among young adults (25-44 years old), over half (205, 63%) of them living in rural areas. The incriminated food item was identified in 161 cases; in most cases (145, 90%) the food item was prepared in the household. The main food category was represented by meat and meat-based products (94, 68.6%). In almost all cases the identified type was BoNT/B (230/231, 99.5%). Fifteen deaths were recorded, and the case fatality rate was 4.6%. Botulism cases were reported annually in Romania. Surveillance data are essential for implementing control measures and adapting educational campaigns according to existing needs.

Complexing Protein-Free Botulinum Neurotoxin A Formulations: Implications of Excipients for Immunogenicity

The formation of neutralizing antibodies is a growing concern in the use of botulinum neurotoxin A (BoNT/A) as it may result in secondary treatment failure. Differences in the immunogenicity of BoNT/A formulations have been attributed to the presence of pharmacologically unnecessary bacterial components. Reportedly, the rate of antibody-mediated secondary non-response is lowest in complexing protein-free (CF) IncobotulinumtoxinA (INCO). Here, the published data and literature on the composition and properties of the three commercially available CF-BoNT/A formulations, namely, INCO, Coretox® (CORE), and DaxibotulinumtoxinA (DAXI), are reviewed to elucidate the implications for their potential immunogenicity. While all three BoNT/A formulations are free of complexing proteins and contain the core BoNT/A molecule as the active pharmaceutical ingredient, they differ in their production protocols and excipients, which may affect their immunogenicity. INCO contains only two immunologically inconspicuous excipients, namely, human serum albumin and sucrose, and has demonstrated low immunogenicity in daily practice and clinical studies for more than ten years. DAXI contains four excipients, namely, L-histidine, trehalosedihydrate, polysorbate 20, and the highly charged RTP004 peptide, of which the latter two may increase the immunogenicity of BoNT/A by introducing neo-epitopes. In early clinical studies with DAXI, antibodies against BoNT/A and RTP004 were found at low frequencies; however, the follow-up period was critically short, with a maximum of three injections. CORE contains four excipients: L-methionine, sucrose, NaCl, and polysorbate 20. Presently, no data are available on the immunogenicity of CORE in human beings. It remains to be seen whether all three CF BoNT/A formulations demonstrate the same low immunogenicity in patients over a long period of time.

Design and characterization of a multi-epitope vaccine against Clostridium botulinum A3 Loch Maree intoxication in humans

Clostridium botulinum Loch Maree expresses an extremely potent botulinum neurotoxin subtype, A3 causing botulism and several gastrointestinal disorders in mammals. Several recombinant vaccines have been developed for human botulism and no vaccine is currently available for the treatment of diseases caused by other virulence factors. Hence, we designed, constructed, and characterized a multi-epitope vaccine from new virulence proteins identified from this organism using an immunoinformatics approach. The vaccine construct used in this study was designed from 6B cell linear epitopes, 12 cytotoxic T cell lymphocyte epitopes, and 15 helper T cell lymphocyte epitopes, with a defensin adjuvant and adjusting linker sequences. A molecular modeling approach was used to model, refine, and validate the 3D structure of the vaccine construct. Molecular docking studies were performed to determine the stability of the molecular interactions between the vaccine construct and human toll-like receptor 7. The in silico molecular cloning was used to clone a codon-optimized synthetic vaccine gene in pCYB1 vector and expressed in Escherichia coli. The results of this study identified six new virulence proteins: peptidoglycan hydrolase, SCP-like extracellular protein, N-acetylmuramoyl-l-alanine amidase, putative membrane protein, drug/metabolite exporter, and bacillolysin. The top B-cell, cytotoxic T-cell lymphocyte, and helper T-lymphocyte epitopes were predicted from these virulence proteins with greater accuracy and reliability. HLA-A*02:01 and HLA-A*03:01 were identified as HLA-A-binding alleles for cytotoxic T-cell lymphocyte epitopes. DRB1*0110 and DRB1*0115 are the dominant alleles that bind to helper T-cell lymphocyte epitopes. The synthetic gene construct was highly expressed in a heterologous host and produced considerable amounts of antigenic protein. The multi-epitope vaccine is more conservative in the sequence-structure-function link, immunogenic with less allergenicity, and possibly provokes cellular and humoral immunity. The present study suggests that the designed multi-epitope vaccine is a promising prophylactic candidate for the virulence and intoxication caused by subtype A3 strains.

The Latent Threat in Wild Birds: Clostridium botulinum

Avian botulism caused by Clostridium botulinum emerged in 1910, affecting birds across North America, leading to severe outbreaks exacerbated by climate change, decreasing water levels, and inadequate wastewater management. While deadly for birds, its epidemiological impact on humans and other animals remains limited. Despite its significance, understanding and controlling the disease remain challenging. This review delves into the pathogen's epidemiology in wild bird populations, exploring the transmission, pathogenicity, clinical symptoms, diagnosis and treatment. The disease's growing concern in wild birds relates to the bacterium's adaptability and expansive spread, evident through genetic similarities among strains across countries. Outbreaks are influenced by environmental factors such as temperature and soil characteristics. Wild birds inadvertently transmit the bacterium, perpetuating the cycle through carcasses and flies. Some species suffer severely, while others, like scavengers, show resistance. Understanding disease mechanisms, involving potential toxin ingestion or internal production, remains ongoing. Clinical signs vary, affecting diverse bird orders. Diagnostic methods evolve, with treatment success varying among affected populations. Prevention and surveillance take precedence due to treatment challenges, emphasising population-based strategies and preventive measures to manage the widespread presence of C. botulinum.

Comparative pathogenomic analysis reveals a highly tetanus toxin-producing clade of Clostridium tetani isolates in Japan

IMPORTANCE

C. tetani is a spore-forming, anaerobic bacterium that produces a toxin causing muscle stiffness and paralysis. Tetanus is preventable with the toxoid vaccine, but it remains a significant public health threat in regions with low vaccine coverage. However, there are relatively few isolates and limited genomic information available worldwide. In Japan, about 100 cases are reported each year, but there have been no nationwide surveys of isolates, and no genomic information from Japanese isolates has been published. In our study, we analyzed the genomes of 151 strains from a limited survey of soil in Kumamoto, Japan. Our findings revealed a high degree of genetic diversity, and we also identified a subset of strains that produced significantly more toxin, which provides new insights into the pathogenesis of tetanus. Our findings lay the foundation for future studies to investigate the distribution and evolution of C. tetani in Japan and neighboring countries.

Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain

To determine whether the neurotoxin BoNT/B2 causing botulism in Spain is clonal, the genetic diversity and phylogenetic relationships of Clostridium botulinum from food-borne episodes and infant cases of the condition were explored. The botulinum toxin gene (bont) subtype, the variable region of the flagellin gene (flaVR), and a seven-gene multi-locus sequence type were examined by sequencing 37 BoNT-positive cultures obtained over the period 2010 to 2022. Out of 37 botulism events, 16 food-borne episodes and 16 infant cases were associated with bont/b2. Eight bont/b2 alleles were detected [nucleotide distance range 0.0259-0.415%, Hunter and Gaston discrimination index (HGDI) 0.71]. The most common bont/b2 allele corresponded to that of strain Prevot 25 NCASE and its single and double locus variations (87.5%). Four known flaVR types were identified (HGDI 0.79), along with one previously unknown (flaVR-15). Sixteen sequence types (STs) (HGDI 0.89) were recorded including seven new STs (ST164-ST170; 10 new alleles) and five new STs (ST171-ST175; with new allele combinations) were also noted. Correlations among some STs and flaVR types were seen. Overall, the present results show that the combined analysis of bont/b2-flaVR-ST at the nucleotide level could be used to track botulism events in Spain. The neurotoxin BoNT/B2 has largely been responsible for human botulism in Spain. The polymorphism analysis of bont/b2, flaVR typing, and sequence type determinations, revealed a wide variety of clones to be responsible for human botulism, ruling out a common source of acquisition. IMPORTANCE Botulism, a potentially fatal disease, is classically characterized by a symmetrical descending flaccid paralysis, which if left untreated can lead to respiratory failure and death. Botulinum neurotoxin (BoNT), produced by certain species of Clostridium, is the most potent biological toxin known, and the direct cause of botulism. This study characterizes the acquisition in Spain of two forms of botulism, i.e., food-borne and infant botulism, which are largely caused by the main neurotoxin BoNT/B2. Polymorphism analysis of the bont/b2 gene, typing of the flagellin variable region sequence (flaVR), and multilocus sequence typing, were used to explore the genetic background of Clostridium botulinum group I. To our knowledge, this is the first phylogenetic and typing study of botulism undertaken in Spain.