Open Access
Vet. Res.
Volume 40, Number 5, September-October 2009
Number of page(s) 13
Published online 18 June 2009
How to cite this article Vet. Res. (2009) 40:51
How to cite this article: Vet. Res. (2009) 40:51
DOI: 10.1051/vetres/2009034

Anchoring tick salivary anti-complement proteins IRAC I and IRAC II to membrane increases their immunogenicity

Laurent Gillet1, Hélène Schroeder1, Jan Mast2, Muriel Thirion1, Jean-Christophe Renauld3, Benjamin Dewals1 and Alain Vanderplasschen1

1  Immunology-Vaccinology (B43b), Department of Infectious and Parasitic Diseases (B43b), Faculty of Veterinary Medicine, University of Liège, B-4000 Liège, Belgium
2  Department Biocontrole, Research Unit Electron Microscopy, Veterinary and Agrochemical Research Centre, VAR-CODA-CERVA, Groeselenberg 99, B-1180 Ukkel, Belgium
3  Ludwig Institute for Cancer Research, Brussels Branch, and Experimental Medicine Unit, Université de Louvain, Brussels, Belgium

Received 25 November 2008; accepted 16 June 2009; published online 18 June 2009

Abstract - Tick salivary proteins are promising targets for the development of anti-tick vaccines. Recently, we described two paralogous anti-complement proteins, called Ixodes ricinus anti-complement (IRAC) proteins I and II, that are co-expressed in tick I. ricinus salivary glands. However, our previous attempts to immunize rabbits against IRAC via infection with recombinant Bovine herpesvirus 4 (BoHV-4) vectors invariably failed although both recombinants expressed high levels of functional IRAC proteins in vitro. As IRAC are soluble monovalent antigens, one of the possible explanations is that monovalent ligation of the B-cell receptor induces receptor activation but fails to promote antigen presentation, a phenomenon that is thought to induce a state of B-cell tolerance. In the present study, we tried to increase IRAC immunogenicity by expressing them as oligovalent antigens. To this end, IRAC were fused to membrane anchors and BoHV-4 vectors expressing these recombinant forms were produced. The immunization potentials of recombinant viruses expressing either secreted or transmembrane IRAC proteins were then compared. While the former did not induce a detectable immune response against IRAC, the latter led to high titres of anti-IRAC antibodies that only marginally affected tick blood feeding. All together, the data presented in this study demonstrate that the immunogenicity of a soluble antigen can be greatly improved by anchoring it in membrane.

Key words: BoHV-4 / IRAC / tick salivary antigen / antigen valency

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© INRA, EDP Sciences 2009