INHIBITION OF HUMAN CYTOMEGALOVIRUS DNA-REPLICATION WITH A PHOSPHOROTHIOATE CHOLESTERYL-MODIFIED OLIGONUCLEOTIDE IS MEDIATED BR BY RAPID CELLULAR-ASSOCIATION AND VIRUS-FACILITATED NUCLEAR-LOCALIZATION

We have previously shown that an antisense phosphorothioate (PS) oligo deoxynucleotide has potent anti-human cytomegalovirus (HCMV) activity (GS Pari, AK Field & JA Smith, Antimicrobial Agents and Chemotherapy 1 995, 39: 1157-1161). We have now used a modified PS oligonucleotide ha ving three 2'-O-methyl nucleotides at the 3' end and four 2'-O-methyl nucleotides at the 5' end, containing a cholesteryl moiety linked to t he 3' end by a novel thiono-triester linkage. This compound, UL36ANTI- M, is superior to the PS (UL36ANTI) version with respect to antiviral potency, melting temperature and nuclease resistance. Also, we show th at cellular association for this oligonucleotide is rapid, occurring w ithin 15 min after treatment and is about 12-fold higher when compared to UL36ANTI. This increased rate of cellular association also correla tes with antiviral properties in that a 15 min incubation with UL36ANT I-M was sufficient to achieve 75% inhibition of viral DNA replication and complete inhibition was achieved after only a 1 h pretreatment. In addition confocal microscopic examination showed a change in subcellu lar distribution from perinuclear to nuclear for oligonucleotides in H CMV-infected human fibroblasts. However, the total amount of cell-asso ciated oligonucleotide was unchanged in infected cells.