Inhibition of Vesicular Stomatitis Virus Replication by Poly(2′-Fluoro-2′-Deoxyuridylic Acid)

Abstract

Poly(2'-fluoro-2'-deoxyuridylic acid) is known to be an effective inhibitor ofthe deoxyribonucleic acid polymerase found within the oncornaviruses. This synthetic polynucleotide was found to inhibit the replication of vesicular stomatitis virus in mouse L cells. The polymer was shown to be capable of inhibiting the viral ribonucleic acid (RNA)-dependent RNA polymerase, and it is proposed that this is the mechanism of antiviral activity. The following observations support this viewpoint: (i) the polymer is most active when added after virus adsorption; (ii) the antiviral activity is not species specific; and (iii) the polynucleotide is nontoxic to the host cell. Conventional methodologies designed to increase nucleic acid uptake by cultured cells do not show an increase in antiviral potency.The antiviral properties of synthetic polynucleotides have, in the past, been associated with either their ability to induce interferon (23) or to enhance the immune response against viral antigens (3). Recently, a more direct mechanism of antiviral activity has been attributed to this class of polymers by the demonstration that certain single-stranded polynucleotides can block the activity of virus-associated nucleic acid polymerases (8,16,17,22). The majority of these data was obtained in studies utilizing the ribonuleic acid (RNA)-dependent deoxyribonucleic acid (DNA) polymerase ofthe oncornaviruses and indicated that the inhibitory polynucleotides blocked the association of enzyme and active nucleic acid template (7). Although the extension of these enzyme analyses to cell culture (16,19,21) and in vivo virus inhibition studies (20) did demonstrate significant antiviral activity, the actual mechanism of inhibition remains unclear. The replication of the oncornaviruses is a complex process that is strongly dependent on host cell metabolism (18), and mechanistic studies involving these viruses may remain difficult and equivocal.Efforts to find a less complex virus-host cell system in which to study the direct inhibitory -activity of the single-stranded polymers demonstrated that the replication ofvesicular stomatitis (VS) virus in mouse L-cell culture was sensitive to poly(2'-fluoro-2'-deoxyuridylic acid)[(dUfl)J], a potent inhibitor of the avian myeloblastosis virus RNA-dependent DNA polymerase (8). This system appeared to be amenable to our studies since VS virus carries a viral-specific, RNA-dependent RNA polymerase, viral replication is relatively independent of host cell DNA and RNA synthesis, and (dUfl), was found to be nontoxic to the host cells. The present study demonstrates that the VS virus RNA polymerase is sensitive to (dUfl)!,, inhibition and the polynucleotide is active when administered postadsorption and presents data which suggest that the inhibition is not mediated by interferon.(A preliminary report on these investigations was presented at the Fourteenth Interscience

Inhibition of vesicular stomatitis virus protein synthesis and infection by sequence-specific oligodeoxyribonucleoside methylphosphonates

“…The effects of oligomers I-IV on VSV production were examined at two points during the infectious cycle, 6-and 24-h postinfection. Inhibition is greater at 6-h postinfection, a period of rapid virus production, than at 24-h postinfection, a period when the infectious cycle is complete and virus production has plateaued (Grosch & Erickson, 1975). These methylphosphonate oligomers exert sequence-specific inhibitory effects on VSV production at both time points (Table IV).…”