Optimization and scale-up of Clostridium perfringens type D culture and epsilon-toxin production: Effects of stirring, glucose and pH adjustment

Detoxification techniques for bacterial toxins: A pathway to effective toxoid vaccines

Bacterial toxins play a critical role in the virulence of many pathogens, leading to serious diseases such as tetanus, diphtheria, botulism, and entrotoxemia. As key virulence factors, these toxins cause significant tissue damage and disease manifestations in infected hosts. Vaccination against these toxins through toxoid vaccines, composed of inactivated forms of the toxins, represents a vital strategy for preventing toxin-mediated diseases. However, creating effective toxoid vaccines necessitates meticulous detoxification processes that ensure the loss of toxicity while retaining the immunogenic properties inherent in the native toxins. This review offers a comprehensive evaluation of the diverse methodologies employed for detoxifying bacterial toxins, highlighting their advantages, limitations, and implications for vaccine development. By detailing comparisons of efficacy, stability, residual toxicity, and clinical applicability, we demonstrate that while traditional methods utilizing chemical reagents (such as formaldehyde) remain widely used, emerging technologies like genetic inactivation and protein engineering present significant advantages. These innovations promise to advance the development of durable and irreversible toxoid vaccines that protect public health and contribute to future vaccine formulation improvements. Ultimately, this knowledge synthesis aims to guide future research efforts and facilitate the design of safer and more effective toxoid vaccines to combat the public health threats posed by toxin-producing bacteria.

Expression and characterization of recombinant epsilon toxin variants of Clostridium perfringens type D in Pichiapastoris

Epsilon toxin (ETX) is the most potent clostridial toxin after tetanus and botulinum neurotoxins. ETX belongs to the heptameric β-pore-forming proteins produced by Clostridium perfringens types B and D, which cause fatal enterotoxemia and significant economic losses in livestock. ETX is synthesized as a protoxin and activated by proteolytic enzymes. Due to limitations in diagnosis and treatment, prevention through vaccination and good management practices is essential. Several commercial vaccines exist for C. perfringens enterotoxemia prevention. However, industrial production is costly and elicits variable immune responses. This has led to the study of recombinant subunit vaccines of ETX with lower toxicity and improved efficacy. The purpose of this study was to produce two versions of the recombinant toxin: truncated epsilon (rETX) and mutated epsilon (rETXH106P). Both were cloned and expressed in a Pichia pastoris expression system, followed by small-scale cultivation and a cytotoxicity assay. The assays confirmed that both recombinant polypeptides were non-toxic. Large-scale cultivation conditions were subsequently adjusted to facilitate the evaluation of kinetic parameters and potential expression, focusing on rETXH106P. This work demonstrated that rETXH106P could potentially be used in a diagnostic kit or as a subunit vaccine candidate against enterotoxemia and other diseases caused by ETX.

Cu-doped Fe3O4 nanoparticles for efficient detoxification of epsilon toxin: Toward substituting magnetically recyclable detoxifying agent for formaldehyde

This research presents the synthesis and characterization of Cu-doped Fe3O4 (Cu-Fe3O4) nanoparticles as a magnetically recoverable and reusable detoxifying agent for the efficient and long-lasting neutralization of bacterial toxins. The nanoparticles were synthesized using the combustion synthesis method and characterized through SEM, XRD, BET, TGA, and VSM techniques. The detoxification potential of Cu-Fe3O4 was compared with traditional formaldehyde (FA) in detoxifying epsilon toxin (ETx) from Clostridium perfringens Type D, the causative agent of enterotoxemia in ruminants. In vivo residual toxicity tests revealed that Cu-Fe3O4 could detoxify ETx at a concentration of 2.0 mg mL-1 within 4 days at room temperature (RT) and 2 days at 37 °C, outperforming FA (12 and 6 days at RT and 37 °C, respectively). Characterization studies using dynamic light scattering (DLS) and circular dichroism (CD) highlighted lower conformational changes in Cu-Fe3O4-detoxified ETx compared to FA-detoxified ETx. Moreover, Cu-Fe3O4-detoxified ETx exhibited exceptional storage stability at 4 °C and RT for 6 months, maintaining an irreversible structure with no residual toxicity. The particles demonstrated remarkable reusability, with the ability to undergo five continuous detoxification batches. This study provides valuable insights into the development of an efficient and safe detoxifying agent, enabling the production of toxoids with a native-like structure. The magnetically recoverable and reusable nature of Cu-Fe3O4 nanoparticles offers practical advantages for easy recovery and reuse in detoxification reactions.