Effect of incorporation of cidofovir into DNA by human cytomegalovirus DNA polymerase on DNA elongation

Abstract

Cidofovir (CDV) (HPMPC) has potent in vitro and in vivo activity against human cytomegalovirus (HCMV), CDV diphosphate (CDVpp), the putative antiviral metabolite of CDV, is an inhibitor and an alternate substrate of HCMV DNA polymerase. CDV is incorporated with the correct complementation to dGMP in the template, and the incorporated CDV at the primer end is not excised by the 3'-to-5' exonuclease activity of HCMV DNA polymerase. The incorporation of a CDV molecule causes a decrease in the rate of DNA elongation for the addition of the second natural nucleotide from the singly incorporated CDV molecule. The reduction in the rate of DNA (36-mer) synthesis from an 18-mer by one incorporated CDV is 31% that of the control. However, the fidelity of HCMV DNA polymerase is maintained for the addition of the nucleotides following a single incorporated CDV molecule. The rate of DNA synthesis by HCMV DNA polymerase is drastically decreased after the incorporation of two consecutive CDV molecules; the incorporation of a third consecutive CDV molecule is not detectable. Incorporation of two CDV molecules separated by either one or two deoxynucleoside monophosphates (dAMP, dGMP, or dTMP) also drastically decreases the rate of DNA chain elongation by HCMV DNA polymerase. The rate of DNA synthesis decreases by 90% when a template which contains one internally incorporated CDV molecule is used. The inhibition by CDVpp of DNA synthesis by HCMV DNA polymerase and the inability of HCMV DNA polymerase to excise incorporated CDV from DNA may account for the potent and long-lasting anti-CMV activity of CDV.

Insights into the mechanism of action of cidofovir and other acyclic nucleoside phosphonates against polyoma- and papillomaviruses and non-viral induced neoplasia

“…dCTP and dATP). Incorporation of one molecule of PMEApp or PMPApp into the growing DNA strand results inevitably in DNA chain termination whereas CDVpp requires two consecutive incorporations to efficiently terminate DNA synthesis, as has been shown for HCMV (Xiong et al, 1996(Xiong et al, , 1997. The selective antiviral activity of ANPs results from the higher affinity of the ANPpp for viral DNA polymerases [that is herpesvirus and poxvirus DNA polymerases and HIV or HBV reverse transcriptases] than for cellular DNA polymerases a, d, and e. Fig.…”

Cidofovir and brincidofovir reduce the pathology caused by systemic infection with human type 5 adenovirus in immunosuppressed Syrian hamsters, while ribavirin is largely ineffective in this model

“…This may lead immediately to DNA chain termination and/or there may be other effects on DNA replication. For example, with the HCMV DNA polymerase, incorporation of CDV causes a $30% decrease in the rate of chain elongation (Xiong et al, 1997). When two successive CDVs are incorporated, chain termination occurs and the 3 0 -to-5 0 exonuclease activity is blocked.…”

Scientific and clinical aspects of the use of cidofovir in recurrent respiratory papillomatosis

“…CMV (unlike HPV) encodes its own viral DNA polymerase which appears to incorporate cidofovir into DNA more readily [14] hence it is effective in delaying CMV retinitis in patients with AIDS [15]. Indeed, cidofovir was approved by the Food and Drug Agency (FDA) for this use in 1996.…”