NR AUQN
AU Flechsig,E.; Klein,M.A.
TI Immunotherapeutic approaches for intervention of prion diseases
QU TSE-Forum, 6. Kongress - Nationale TSE-Forschungsplattform, Greifswald 26.6.-28.6.2006, Vortrag V-06
PT Konferenz-Vortrag
AB
Because of systemic immune tolerance against the cellular prion protein (PrPc), immunotherapeutic strategies with active immunisation are limited to protection against prion diseases. To develop a novel prion vaccine, we first designed a DNA vaccine expressing mouse PrP and immune stimulatory helper T cell epitopes of the tetanus toxoid that has previously been reported to break tolerance to self antigens. This improved strategy evoked a strong PrP-specific humeral and cellular immune response in PrP null mice, but only low antibody titers were found in immunized wild-type mice. Furthermore, vaccination with a DNA vaccine prime and recombinant PrP boost failed to protect mice against prion disease. Improved vaccination studies with recombinant PrP containing these helper T cell epitopes are currently investigated.
In a second part, we have generated PrP-specific monoclonal antibodies to further elucidate the underlying mechanisms of PrPsc clearance and elimination of prion infectivity after passive immunisation. All antibodies analysed so far detect both PrPc and PrPsc in mouse brain homogenates by Western blotting and bind PrPc on the surface of murine N2a cells by FACS analysis. Their binding sites on PrPc were mapped by transient expression of PrPc deletions and their concentrations for 50% inhibition of PrPsc accumulation on RML-infected ScN2a cells were determined. Antibodies were further characterized in cell culture studies. So far, the inhibitory effect correlates with the ability of the antibodies to retain PrPc on cell surface, but other possible mechanisms are conceivable and will be discussed.
AD Eckhard Flechsig and Michael Klein, Prion Research Group, Institute of Virology and Immunobiology, Würzburg, Germany
SP englisch
PO Deutschland
OR Tagungsband