[Structural and functional specificity of the Dichelobacter nodosus pili. Synthesis of the protein pilin of D. nodosus in various bacterial recombinant strains].

ABSTRACT

The ovine foot rot is a severe infectious disease of sheep. Dichelobacter nodosus is an essential pathogen of this disease. An obligatory anaerobic gram-negative rod-shaped microorganism has slow rate of accumulating bacterial density and fastidious growth requirements. This causes obstacles to vaccine production and makes it difficult to diagnose the disease. The diagnosis in this case is more expensive. Fimbriae (or pili) are one of the major factors of virulence of D. nodosus. Their antigenic and immunogenic properties make them good vaccine components for elevated immunogenicity. Since the nucleotide sequence of the fimA gene encoding fimbrial subunit was determined, attempts to produce recombinant pili were undertaken. The production of the genetic-engineering fimbriae would allow the price of the vaccines to be reduced and their manufacture to be simplified. The vaccine immunogenicity is increased in this case. At first, E. coli was selected as an expression system, but morphogenetic expression of the pili was not achieved on its surface because of some differences in the biogenesis and structure of fimbriae from D. nodosus. Successful morphogenesis of the pili was achieved in Pseudomonas aeruoginosa, which had closest similarity in the structure of pili. The level of the immunity obtained after immunization of the sheep with recombinant pili was similar to the level of the immunity after native pili or whole cells of D. nodosus had been used. This review contains information regarding the recombinant strains of Pseudomonas aeruoginosa obtained using fimbriae of D. nodosus and expression of pilin genes in different bacterial systems.