Structural and functional specificity of Dichelobacter nodosus Pili: Synthesis of pilin protein D. nodosus in various recombinant bacterial strains

Sheep hoof rot is a serious infectious disease specific to this type of animal; its pathogenic agent is anaerobic gram-negative bacillus Dichelobacter nodosus. Very strict requirements for cultivation conditions and slow rate of accumulation of bacterial mass make the vaccine and diagnistcs production laborious and expensive. Fimbriae (pili) are one of the main factors of D. nodosus virulence, since they have both antigenic and immunogenic properties that allow them to be added to vaccines to intensify immunogenicity. After it was determined that the fimA gene, which encodes the fimbrial subunit, attempts were made to obtain recombinant pili. The production of genetically engineered fimbriae serves to simplify and lower the cost of the process of vaccine production, as well as to improve immune-protective qualities of the obtained preparations. The first system of bacterial expression was selected for E. coli, however, the assembly of D. nodosus pili on its surface failed due to significant differences in the biogenesis and fimbria structure of these microorganisms. The morphogenesis of D. nodosus pili succeeded in Pseudomonas aeruginosa, which is characterized by the most similar structure of pilin subunits. Sheep’s immunity after injection of recombinant fimbria, native fimbria, and whole cells of D. nodosus was almost analogous in intensity. The article presents a review of data from publications on the production of recombinant cultures of P. aeruginosa with D. nodosus pili and expression of pilin genes in various bacterial systems.