Exploring E. coli-based expression of genetically inactivated tetanus toxin for vaccine development

Abstract

Tetanus toxin, a highly potent neurotoxin produced by Clostridium tetani, is the primary agent responsible for causing tetanus. This serious, potentially fatal disease can be effectively prevented through vaccination. Thanks to successful vaccination campaigns, tetanus has become exceedingly rare in both developed and most developing countries. However, the widespread presence of C. tetani spores in the environment means that tetanus cannot be completely eradicated, underscoring the ongoing need for vaccination. Traditionally, tetanus vaccines are produced by cultivating C. tetani, extracting a crude form of the tetanus toxin, and then chemically inactivating it for use in immunization. This method has proven clinically effective and is in widespread use. A challenge with this approach, however, is that the vaccine contains hundreds of various C. tetani proteins, with the active component making up only a variable and small fraction of the overall vaccine mass. To improve the current tetanus vaccine, there is potential in the recombinant production of a genetically inactivated tetanus vaccine. Prior studies have demonstrated the feasibility of engineering the full-length tetanus toxin in E. coli, and our current work builds on this foundation. We have successfully cloned the complete tetanus toxin open reading frame into the pMAL expression vector. This step was followed by the creation of a genetically inactivated protein, achieved through standard site-directed mutagenesis which altered 8 critical amino acid residues. These mutations have been confirmed via sequencing, ensuring that the toxin is genetically inactivated and thus does not require chemical inactivation for vaccine production. Our present focus is on optimizing the expression of this protein in E. coli. Following this, we intend to conduct thorough assessments of the biochemical and immunological properties of the recombinant tetanus toxin. This research represents a promising avenue towards enhancing the efficacy and specificity of tetanus vaccines, potentially improving global health outcomes.