INHIBITION OF HERPES-SIMPLEX VIRUS-REPLICATION BY ANTISENSE OLIGO-2'-O-METHYLRIBONUCLEOSIDE METHYLPHOSPHONATES

Antisense oligonucleoside methylphosphonates complementary to the 12 n ucleotides found at the intron/exon junction of the splice acceptor si te of herpes simplex virus type 1 (HSV-1) immediate early mRNAs 4 and 5 were synthesized. The methylphosphonate oligomers contained either 2 '-deoxyribose nucleosides, d-OMPs, or 2'-O-methylribose nucleosides, m r-OMPs. At 37 degrees C, the affinity of the mr-OMP for a complementar y 12-mer RNA target was approximately four times higher than that of t he corresponding d-OMP as measured by a constant activity gel electrop horesis mobility shift assay. An mr-OMP whose sequence contained two m ismatched bases did not bind to the RNA target under these conditions. The mr-OMP also showed improved ability to inhibit HSV-1 replication in HSV 1 infected Vero cells in culture. Thus the IC50 of the mr-OMP w as five times less than that of the d-OMP: No inhibition was observed by the mismatched mr-OMP, and no inhibition of herpes simplex virus ty pe 2 (HSV-2) replication was observed with any of the oligomers. These results demonstrate a direct correlation between oligomer binding aff inity and antisense activity in cell culture and suggest that oligo-2' -O-methylribonucleoside methylphosphonates are promising candidates fo r development of effective antisense reagents.