Metabolic pathways of N-methanocarbathymidine, a novel antiviral agent, in native and herpes simplex virus type 1 infected Vero cells.

Abstract

N-methanocarbathymidine ((N)-MCT), a thymidine analog incorporating a pseudosugar with a fixed Northern conformation, exhibits potent antiherpetic activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). This study contrasts the metabolic pathway of (N)-MCT and the well-known antiherpetic agent ganciclovir (GCV) in HSV-1-infected and uninfected Vero cells. Treatment of HSV-1 infected Vero cells immediately after viral infection with (N)-MCT profoundly inhibited the development of HSV-1 infection. Using standard plaque reduction assay to measure viral infection, (N)-MCT showed a potency greater than that of ganciclovir (GCV), the IC50s were 0.02 and 0.25 microM for (N)-MCT and GCV, respectively. (N)-MCT showed no cytotoxic effect on uninfected Vero cells (CC50>100 microM). Dose and time dependence studies showed high levels of (N)-MCT-triphosphate ((N)-MCT-TP), and GCV-triphosphate (GCV-TP) in HSV-1-infected cells incubated with (N)-MCT or GCV, respectively. In contrast, uninfected cells incubated with (N)-MCT showed elevated levels of (N)-MCT-monophosphate only, while low levels of mono, di- and triphosphates of GCV were found following incubation with GCV. Although the accumulation rate of (N)-MCT and GCV phosphates in HSV-1-infected cells were similar, the decay rate of (N)-MCT-TP was slower than that of GCV-TP. These results suggest that: (1) the antiviral activity of (N)-MCT against herpes viruses is mediated through its triphosphate metabolite; (2) in contrast to GCV, the diphosphorylation of (N)-MCT in HSV-1- infected cells is the rate limiting step; (3) (N)-MCT-TP accumulates rapidly and has a long half-life in HSV-1-infected cells; and (4) HSV-tk catalyzed the mono, and diphosphorylation of (N)-MCT while monophosphorylating GCV only. These results provide a biochemical rational for the highly selective and effective inhibition of HSV-1 by (N)-MCT.

• Authors: Livnat Zalah, Mahmoud Huleihel, Esther Manor, Alexander Konson, Harry Ford Jr, Victor E Marquez, David G Johns, Riad Agbaria
• Journal: Antiviral research (Antiviral Res) Vol. 55 Issue 1 Pg. 63-75 (Jul 2002) ISSN: 0166-3542 [Print] Netherlands
• PMID: 12076752 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Antiviral Agents
• Polyphosphates
• (north)-methanocarbathymidine
• triphosphoric acid
• Ganciclovir
• Thymidine

Topics

• Animals
• Antiviral Agents (metabolism, pharmacology)
• Chlorocebus aethiops
• Cytopathogenic Effect, Viral (drug effects)
• Ganciclovir (metabolism, pharmacology)
• Herpesvirus 1, Human (drug effects, physiology)
• Phosphorylation
• Polyphosphates (metabolism)
• Thymidine (analogs & derivatives, pharmacology)
• Vero Cells