%0 Journal Article
%T The effects of maribavir on the autophosphorylation of ganciclovir resistant mutants of the cytomegalovirus UL97 protein
%A Claire D Shannon-Lowe
%A Vincent C Emery
%J Herpesviridae
%D 2010
%I BioMed Central
%R 10.1186/2042-4280-1-4
%X Wild type and site directed mutant forms of the human cytomegalovirus UL97 gene product were expressed using recombinant baculoviruses and the purified products used to assess the effects of maribavir on the ganciclovir (GCV) kinase and protein kinase (PK) activities.Maribavir was a potent inhibitor of the autophosporylation of the wild type and all the major GCV resistant UL97 mutants analysed (M460I, H520Q, A594V and L595F) with a mean IC50 of 35 nM. The M460I mutation resulted in hypersensitivity to maribavir with an IC50 of 4.8 nM. A maribavir resistant mutant of UL97 (L397R) was functionally compromised as both a GCV kinase and a protein kinase (~ 10% of wild type levels). Enzyme kinetic experiments demonstrated that maribavir was a competitive inhibitor of ATP with a Ki of 10 nM.Maribavir is a potent competitive inhibitor of the UL97 protein kinase function and shows increased activity against the M460I GCV-resistant mutant which may impact on the management of GCV drug resistance in patients.The UL97 gene of human cytomegalovirus encodes a 690 amino acid nuclear serine/threonine protein kinase that is present in the virion and is critical for efficient viral replication [1-8]. The precise function of UL97 in the replication cycle has not been fully elucidated but UL97 has been implicated in replication, viral DNA packaging, nuclear egress, virion morphogenesis and cell cycle manipulation [9-15]. The full range of targets for UL97 kinase action are also undefined although the viral UL44 protein is one viral substrate [16] and pUL97 complexes with the tegument phosphoprotein pp65 (ppUL83)[17]. UL97 also phosphorylates the antiviral nucleosides ganciclovir (GCV) and acyclovir [18-21], the former being the major drug currently used to control HCMV replication in vivo [22,23]. In the era preceding the deployment of highly active antiretroviral therapy for HIV infection, long term GCV therapy for cytomegalovirus retinitis led to the development of GCV resistance in
%U http://www.herpesviridae.org/content/1/1/4