Recombinant Vaccine Design Against Clostridium spp. Toxins Using Immunoinformatics Tools.

The emergence of recombinant DNA technology has led to the exploration of the use of the technology to develop novel vaccines. With a fundamental role in vaccines design, several immunoinformatics tools have been created to identify isolated epitopes that stimulate a specific immune response, contributing to effective vaccines development. In the past, vaccine development projects relied entirely on animal experimentation, a relatively expensive and time-consuming process. Currently, use of immunoinformatics tools play a vital role in the antigen analysis and refinement, allowing the identification of possible protective epitopes capable of stimulating convenient humoral or cellular immune responses, in addition to facilitating time and cost reduction of vaccine production. The vaccination aimed at bacterial species of Clostridium spp. has been considered a promising example of use of these approaches in recent years. Based on the literature search, it is possible to understand the best immunoinformatics software used by researchers that facilitate recombinant vaccine antigens design and development. This chapter presents an overview of how these tools are supporting the antigen engineering, aiming at increasing the efficiency of inducing protective immune response in animals.

Evaluation of the expression and immunogenicity of four versions of recombinant Clostridium perfringens beta toxin designed by bioinformatics tools.

Beta toxins (CPB) produced by Clostridium perfringens type B and C cause various diseases in animals, and the use of toxoids is an important prophylactic measure against such diseases. Promising recombinant toxoids have been developed recently. However, both soluble and insoluble proteins expressed in Escherichia coli can interfere with the production and immunogenicity of these antigens. In this context, bioinformatics tools have been used to design new versions of the beta toxin, and levels of expression and solubility were evaluated in different strains of E. coli. The immunogenicity in sheep was assessed using the molecule with the greatest potential that was selected on analyzing these results. In silico analyzes, greater mRNA stability (-169.70 kcal/mol), solubility (-0.755), and better tertiary structure (-0.12) were shown by rCPB-C. None of the strains of E. coli expressed rFH8-CPB, but a high level of expression and solubility was shown by rCPB-C. Higher levels of total and neutralizing anti-CPB antibodies were observed in sheep inoculated with bacterins containing rCPB-C. Thus, this study suggests that due to higher productivity of rCPB-C in E. coli and immunogenicity, it is considered as the most promising molecule for the production of a recombinant vaccine against diseases caused by the beta toxin produced by C. perfringens type B and C.

Inactivated recombinant Escherichia coli as a candidate vaccine against Clostridium perfringens alpha toxin in sheep.

Clostridium perfringens type A is the causative agent of gas gangrene and gastroenteric ("yellow lamb disease") disease in ruminants, with C. perfringens alpha toxin (CPA) being the main virulence factor in the pathogenesis of these illnesses. In the present study, we have developed recombinant Escherichia coli bacteria expressing rCPA and used it to vaccinate rabbits and sheep. Doses of up to 200 µg of rCPA used for inoculation, induced 13.82 IU.mL-1 of neutralizing antitoxin in rabbits, which is three times higher than that recommended by the USDA (4 IU.mL-1). In sheep, recombinant bacteria induced antitoxin titers of 4 IU.mL-1, 56 days after the first dose. rCPA which was expressed, mainly, in inclusion bodies, was not found to influence the immunogenicity of the vaccine. The recombinant Escherichia coli bacterin, produced simply and safely, is capable of affording protection against diseases caused by C. perfringens CPA. The current findings represent a novel production method for CPA vaccines potentially applicable to veterinary medicine.