ANTISENSE RNA INHIBITING BOVINE LEUKEMIA-VIRUS REPRODUCTION IN CELL-CULTURE EFFICIENTLY BINDS THE RNA TARGET IN-VITRO

To find the optimal targets for antisense RNAs (asRNAs) in retroviral genome, two series of antiviral asRNA genes were constructed: one unde r the human adenovirus type 5 VAI RNA promoter, and the other under th e bovine leukemia virus (BLV) promoter from the LTR U3 region. Various fragments of the 5'-terminal region of the BLV genome were chosen as targets for asRNA action. In CC81 cells, the asRNA genes under the VAI RNA promoter had low antiviral activity despite of efficient expressi on. By contrast, the asRNA genes under the BLV LTR U3 promoter efficie ntly inhibited viral reproduction, and the asRNAs directed against the viral DNA fragment in the R region covering a splice donor site for a ll subgenomic viral mRNAs had the highest antiviral effect (about 98%) . We studied the kinetics of in vitro interaction of the different asR NAs with their RNA targets and calculated the binding rate constants, which differed by an order of magnitude for the asRNA having a high an tiviral effect and for the one with no detectable antiviral effect but directed against the same viral target. The data obtained testify tha t the efficiency of the asRNA-target RNA interaction characterized by the binding rate constant seems to be the most essential factor for th e inhibition of viral reproduction by asRNAs.