Charakterisierung funktioneller Domänen des vektoriell exprimierten Glykoproteins des Virus der Bornaschen Krankheit

In this thesis it was succeeded to establish an expression system for BDV-glycoprotein. This system yielded a BDV-glycoprotein, which correlates with the wild type glycoprotein in all characteristics. It is cloven at Amino acid position 246-249 by Furin. The transport to the cell surface and the therewith associated glycosylation conform to the natural glycoprotein. Therefore, it was possible to make the further analysis with the help of a vectorialy expressed glycoprotein, which complies with the glycoprotein of infected cells. As it is fact, that many proteins which are involved in cell fusion are dimmers or trimers, so this was investigated for the BDV-glycoprotein, too. Superior, oligomeric forms of the BDV glycoprotein could be demonstrated, in all probability, dimers and trimers of this protein. By means of this new expression system it was possible to show, that the BDV glycoprotein is able to arrange the cell-cell-fusion on its own after the subsidence of the pH-value. For this reaction it is essential that the BDV-glycoprotein has been cloven before. Compared to the amount in infected cells, the increased fusion activity of BDV-glycoprotein stable cell line could be explained by the higher expression level and the more efficient transport to the cell surface. An inhibition of the fusion of about 50% could be attained by the treatment of the cells with Heparin before lowering the pH-value. Through substitution in the amino acid region 296-305 in the c-terminal subunit of BDV-glycoprotein it could be shown that this region plays an important role during the fusion process. As a conclusion it can be stated, that the fusion peptide is located in this domain. In order to precisely characterise the fusion peptide, further investigations have to be carried out.