The nucleoside phosphonates cidofovir (CDV) and (S)-9-[3-hydroxy-(2-phosphonomethoxy)propyl]adenine [(S)-HPMPA] are analogs of dCMP and dAMP, respectively. Collectively these drugs are effective inhibitors of a wide range of DNA viruses, RNA viruses, and retroviruses. Because they are nucleotide analogs, the drugs are thought to target viral polymerases and inhibit viral genome replication. However, the precise mechanism by which these drugs block viral growth remains unclear. We have studied the mechanism of action of these antivirals against three viral polymerases, vaccinia virus DNA polymerase and the reverse transcriptases from human immunodeficiency virus type 1 (HIV-1) and Moloney murine leukemia virus (MMLV). In vitro experiments using the active intracellular metabolites of CDV and (S)-HPMPA, CDV diphosphate (CDVpp) and (S)-HPMPA diphosphate [(S)-HPMPApp], respectively, showed that the drugs are substrates for each enzyme and can be incorporated into DNA without causing chain termination, although the rate of DNA elongation catalyzed by the vaccinia virus and MMLV polymerases is slowed. We have also found that incorporation of CDV or (S)-HPMPA blocked the 3′-to-5′ proofreading exonuclease activity of the vaccinia virus DNA polymerase. In addition, we determined that when these drugs are incorporated into a template DNA strand, they inhibited replication across the drug lesion. These results indicate that although CDV and (S)-HPMPA can inhibit some enzymes when incorporated into the primer strand, the main effects of drug action occur when they are incorporated into the template strand. Our findings point to a new avenue of targeted drug design, one in which nucleoside or nucleotide analogues are efficient substrates for the viral nucleic acid polymerase, do not inhibit primer strand elongation, but exert their effects in subsequent rounds of nucleic acid synthesis. / Virology
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/534 |
| Date | 11 1900 |
| Creators | Magee, Wendy C |
| Contributors | Evans, David H (Medical Microbiology and Immunology), Tyrrell, D Lorne J (Medical Microbiology and Immunology), Hobman, T (Cell Biology), Humar, A (Medicine), Götte, M (Microbiology and Immunology, McGill University) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 7054874 bytes, application/pdf |
| Relation | Mechanism of inhibition of vaccinia virus DNA polymerase by cidofovir diphosphate. Magee WC, Hostetler KY, Evans DH. Antimicrob Agents Chemother. 2005 Aug;49(8):3153-62., Cidofovir and (S)-9-[3-hydroxy-(2-phosphonomethoxy)propyl]adenine are highly effective inhibitors of vaccinia virus DNA polymerase when incorporated into the template strand. Magee WC, Aldern KA, Hostetler KY, Evans DH. Antimicrob Agents Chemother. 2008 Feb;52(2):586-97., Production and characterization of antibodies against vaccinia virus DNA polymerase. Magee WC, Shahhosseini S, Lin YC, Suresh MR, Evans DH. J Virol Methods. 2009 Oct;161(1):44-51. |
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