CHARACTERIZATION OF THE REVERSE-TRANSCRIPTASE OF A HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 GROUP-O ISOLATE

The catalytic properties and sensitivity to different inhibitors have been determined for the reverse transcriptase (RT) of group O human im munodeficiency virus type 1 (HIV-l). The RT-coding region was cloned f rom a new HIV-1 group O isolate from Spain, expressed in Escherichia c oil, and purified by affinity chromatography. This new RT showed 79% a mino acid sequence identity with the corresponding enzyme of group M s ubtype B strain BH10. The two enzymes showed very similar kinetics of RNA-dependent DNA polymerization using homopolymeric template-primers and RNase H specific activity. Inhibitor sensitivity to ddTTP and 3'-a zido-2',3'-dideoxythymidine triphosphate (AmP) was also similar for bo th enzymes. However, the two enzymes differed dramatically in their se nsitivity to several inhibitors. While the RT of the BH10 isolate was sensitive to nevirapine and loviride (IC50 ranged from 0.16 to 8.2 mu M depending on the substrates used), the enzyme of the Spanish HIV-1 g roup O isolate showed high-level resistance to those compounds (IC50 > 200 mu M). The amino acid sequence of the RT of group O HIV-1 contain s three amino acids (Cys-181, Glu-179, and Gly-98), which are found in group M subtype B strains resistant to nonnucleoside RT inhibitors. T he recombinant group O HIV-1 RT should be useful for studies aimed at discovering and designing drugs directed toward group O isolates of HI V-1. (C) 1997 Academic Press.