Investigation into the mode of action of R-91650, an arylpiperazinyl fluoroquinolone, on feline immunodeficiency virus replication inhibitory activity

The mode of action of R-91650, an arylpiperazinyl fluoroquinolone, on felin e immunodeficiency virus (FIV) replication inhibitory activity was investig ated. R-91650 inhibited replication of FIV at non-cytotoxic concentration l evels in both acutely infected peripheral blood mononuclear cells and chron ically infected P-CrFK cells. The compound reduced the intracellular p24 co ncentration levels in P-CrFK cells in a dose-dependent manner. Northern blo t analysis revealed that R-91650 selectively prevented the accumulation of FIV mRNA in P-CrFK cells. However, the compound did not inhibit FIV-long te rminal repeat (LTR) promoter activity in the reporter gene expression analy sis. These data suggest that R-91650 is a novel inhibitor of FIV replicatio n that inhibits a certain step or steps following transcription initiation of the FIV-LTR promoter.