Regulation of the Borna disease virus polymerase complex by the viral nucleoprotein p38 isoform. Brief Report

Borna disease virus (BDV) polymerase can be reconstituted by co-expression of the viral genes N, P and L. N codes for two proteins, p39 and p38, resulting from alternative translation initiation. Using a viral minireplicon system we observed that unlike p39, p38 was almost completely inactive when expressed with P and L alone. Since BDV polymerase requires a 10-20 fold excess of N protein over P for high activity, we determined whether p38 might serve as buffer that influences the viral N:P ratio. We demonstrate that p38 efficiently rescued BDV polymerase activity in cells expressing unfavorably high amounts of P.