Antiviral effect of an oligo(nucleoside methylphosphonate) complementary to the splice junction of herpes simplex virus type 1 immediate early pre-mRNAs 4 and 5

Selective inhibition of regulatory immediate early (IE) genes of herpes simplex virus type 1 (HSV-1) should inhibit virus growth. Treatment of HSV-1-infected cells with the oligo(nucleoside methylphosphonate) d(TpCCTCCTG) (deoxynucleoside methylphosphonate residues in italic), which is complementary to the acceptor splice junction of HSV-1 IE pre-mRNA 4 and 5, before (1-24 hr) or at the time of infection caused a dose-dependent inhibition in virus replication. Virus titers were decreased 50% and 90% in cells treated with 25 μM and 75 μM oligomer, respectively; at 300 μM, a 99% reduction in virus production was observed. Viral DNA synthesis was reduced 70-75% and there was a 90% reduction in synthesis of viral proteins, including other IE species and viral functional (130-kDa major DNA-binding) and structural (glycoprotein gB) proteins. In the same concentration range, d(TpCCTCCTG) caused a minimal reduction (0-30%) in protein synthesis and growth rates (< 40%) of uninfected cells. The data suggest that oligo(nucleoside methylphosphonate)s may be effective in antiviral chemotherapy.