Utilisation de Yersina comme vecteur d'expression de protéines ou d'antigènes vaccinaux à usage vétérinaire
(1993)
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- Authors
- Supervisors
- Cornélis, Guy R.
- Abstract
- Bacteria of the genus Yersinia are causative agents of a variety of diseases in humans and in animals ranging from gastroenteritis to plague. <BR> Yersiniae are pathogens because of the presence of a virulence plasmid of +/-70kb called pYV. At 37°C and in media deprived in calcium, pYV+ Yersiniae restrict their growth and secrete several proteins of first importance in the virulence of the bacteria. Those proteins, called Yop, are produced in the course of infection and are very immunogenic. In vitro, they are exported without any signal peptide in the culture supernatant by an original system involving chaperone proteins. <BR> The benign character of Y. enterocolitica infections, the marked tropism of this bacteria for the lymphoid tissue and the present knowledge of the virulence functions and their regulation have prompted G. Cornelis and coll. to convert Y. enterocolitica into a live oral carrier to deliver foreign antigens to the gut associated lymphoid tissue. The originality of the system lay on the insertion of a foreign gene downstream from a yop promoter to bring about his expression in the host, presumably when the bacteria interact with the immune system. The oral inoculation to mice of Y. enterocolitica expressing the cholera B-subunit (CT-b) under the control of a yop promoter induces an humoral immune response directed to CT-B. <BR> In collaboration with the mucosal immunology group headed by professor J.-P. Vaerman, we have studied the immune response of mice inoculated with recombinant Y. enterocolitica expressing, without secretion, the cholera toxin B sub-unit. We showed that mice generated anti-cholera plasma IgG, intestinal sIgA and bronco-alveolar sIgA. Above all, vaccinated mice showed a protection against a lethal gut cholera toxin challenge. <BR> Those results prompted us to construct and study recombinant Y. enterocolitica secreting eukaryotic antigens fused to the amino-terminus of a Yop protein. <BR> We constructed several expression vectors for Yersinia, which permit the cloning of foreign gene in the three reading frames into a yop gene. By using those vectors, we produced into Y. enterocolitica fragments of the hemagglutinin if an Influenza A virus, the glycoprotein gp50 of Pseudorabies virus and the major surface antigen (P30) to Toxoplasma gondii. We showed that the produced chimeric proteins were recognized by sera from animals immunized with the infectious agents from which cloned antigen. <BR> The sub-cutaneous inoculation (with complete Freund adjuvant) of the purified recombinant hybrid proteins led to a high humoral immune response directed against the foreign antigen. However, repeated intragastric or intraperitoneal inoculations of recombinant bacteria secreting the same hybrid proteins failed to generate a humoral or mucosal immune response against the antigens. The recombinant bacteria generated an immune response against the foreign antigens if the hybrid proteins were not secreted. <BR> We have thus shown that the secretion system of Y. enterocolitica is a wonderfull tool for the production and the secretion of recombinant eukaryotic proteins into the culture medium. This system failed however to induce an immune response in mice inoculated with recombinant live bacteria. We have demonstrated that Y. enterocolitica could however serve as a live oral carrier to deliver non secreted antigens to the immune system
- Affiliations
Citations
Biot, T. (1993). Utilisation de Yersina comme vecteur d’expression de protéines ou d’antigènes vaccinaux à usage vétérinaire. https://hdl.handle.net/2078.5/110926