Use of the bovine leukaemia virus LTR U3 promoter for expressing antisense antiviral RNAs and competitive inhibition of viral infection in cell culture.

Abstract

Use of viral inducible promoters which can be activated by virus-specific transactivator proteins to drive expression of antisense (as)RNA genes appears to be an attractive approach to inhibit virus infections in vivo. To this end, we have constructed an asRNA gene expressed from the bovine leukaemia virus (BLV) U3 promoter that is complementary to the R-U5 region of the BLV genome. This is the region that is most susceptible to inhibition by asRNA. With plasmid pLU, which expresses the asRNA gene under the control of the BLV U3 promoter, 75 % inhibition of virus replication was attained in CC81 cells (the molar ratio of pLU DNA over BLV proviral DNA in the transfection mixture was 5 : 1). Plasmid pLT, which contains only the BLV U3 promoter without any asRNA-coding region,