Inhibition of Borna disease virus multiplication by interferon: cell line differences in susceptibility

It has previously been reported that de novo infection of primary rabbit brain cells with Borna disease virus (BDV) can be blocked with interferon-alpha/beta (IFN), whereas this cytokine has no inhibitory effect on BDV in persistently infected rat lung cells [v. Rheinbaben et al., J. Gen. Virol. (1985) 66: 2,777-2,780]. It remained unclear, however, whether these results indicated that IFN exclusively targets early steps of the BDV replication cycle or whether they simply reflected cell line differences. We now show that BDV replication was effectively inhibited by IFN in both acutely and persistently infected monkey Vero cells. By contrast, IFN had no clear protective effect on either de novo or persistent BDV infections of rat C6 glioblastoma cells. IFN protected C6 cells from the cytopathic effects of vesicular stomatitis virus, excluding the possibility that these cells are devoid of a functional IFN system. In primary rat fibroblasts and in a human oligodendroglial cell line, IFN induced an efficient antiviral state against BDV. These results indicate that BDV is highly susceptible to the antiviral effect of IFN in some cell lines, while others seem to lack undefined components of the IFN system which mediate protection against BDV.