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Current Treatment Options in Infectious... 2014In treating cytomegalovirus (CMV) infection, it is crucial to decide whether one is treating pre-emptively or if one is treating established disease. Disease may be... (Review)
Review
In treating cytomegalovirus (CMV) infection, it is crucial to decide whether one is treating pre-emptively or if one is treating established disease. Disease may be further divided into viral syndrome and tissue-invasive disease. Generally, mild disease in immunosuppressed patients may be treated with oral valganciclovir. Treatment may also be started with valganciclovir for CMV retinitis in AIDS patients. In other tissue-invasive syndromes, starting with intravenous ganciclovir or foscarnet at full doses (adjusted for renal function) is preferred. Treatment at full doses should be continued until symptom resolution and until blood antigenemia (or DNAemia) is cleared. Patients receiving treatment must be closely monitored for side effects to the drugs, as well as for response. Drug-resistant CMV is a therapeutic challenge; combination therapy with both ganciclovir and foscarnet may be tried. In extreme cases, resorting to unconventional agents like leflunomide or maribavir may be necessary. Immune reconstitution, through reduction in immunosuppression, or the introduction of anti-retroviral therapy, should be attempted. CMX001 is a novel agent active against double-stranded viruses; thus far, resistance to CMX001 does not confer resistance to ganciclovir or foscarnet. Hence, prophylaxis or pre-emptive treatment with CMX001 may allow the use of ganciclovir or foscarnet for treatment.
PubMed: 25999800
DOI: 10.1007/s40506-014-0021-5 -
Antimicrobial Agents and Chemotherapy 2014Methylenecyclopropane nucleoside (MCPN) analogs are being investigated for treatment of human cytomegalovirus (HCMV) infection because of favorable preclinical data and...
Methylenecyclopropane nucleoside (MCPN) analogs are being investigated for treatment of human cytomegalovirus (HCMV) infection because of favorable preclinical data and limited ganciclovir cross-resistance. Monohydroxymethyl MCPNs bearing ether and thioether functionalities at the purine 6 position have antiviral activity against herpes simplex virus (HSV) and varicella-zoster virus (VZV) in addition to HCMV. The role of the HCMV UL97 kinase in the mechanism of action of these derivatives was examined. When tested against a kinase-inactive UL97 K355M virus, a moderate 5- to 7-fold increase in 50% effective concentration (EC50) was observed, in comparison to a 13- to 25-fold increase for either cyclopropavir or ganciclovir. Serial propagation of HCMV under two of these compounds selected for three novel UL97 mutations encoding amino acid substitutions D456N, C480R,and Y617del. When transferred to baseline laboratory HCMV strains, these mutations individually conferred resistance to all of the tested MCPNs, ganciclovir, and maribavir. However, the engineered strains also demonstrated severe growth defects and abnormal cytopathic effects similar to the kinase-inactive mutant. Expressed and purified UL97 kinase showed in vitro phosphorylation of the newly tested MCPNs. Thus, HCMV UL97 kinase is involved in the antiviral action of these MCPNs, but the in vitro selection of UL97-defective viruses suggests that their activity against more typical ganciclovir-resistant growth-competent UL97 mutants may be relatively preserved.
Topics: Antiviral Agents; Cell Line; Cyclopropanes; Cytomegalovirus; Ether; Humans; Sulfides
PubMed: 24145545
DOI: 10.1128/AAC.01726-13 -
Antiviral Research Nov 2013Therapeutic strategies controlling human cytomegalovirus (hCMV) infection are limited due to adverse side effects and emergence of antiviral resistance variants. A...
Therapeutic strategies controlling human cytomegalovirus (hCMV) infection are limited due to adverse side effects and emergence of antiviral resistance variants. A compound being evaluated for treating hCMV disease is maribavir (MBV) which disrupts replication by inhibiting the viral kinase pUL97. Previous studies have demonstrated that the antiviral activity of MBV is sensitive to the proliferation state of the infected cell. In these studies, we were interested in determining whether inhibition of the pro-proliferative transcription factor, signal transducer and activator of transcription-3 (STAT3), could influence the antiviral activity of MBV. The addition of the STAT3 inhibitor, S3i-201, during infection altered hCMV-mediated changes in cell cycle protein expression. Upon combining S3i-201 with MBV, our data suggest that STAT3 inhibition is acting synergistically with MBV to inhibit infection in vitro. Furthermore, specific concentrations of S3i-201 and MBV induced caspase-dependent death of infected but not uninfected cell. Our studies suggest that treating infection with both S3i-201 and MBV is a novel approach to inhibit hCMV replication.
Topics: Aminosalicylic Acids; Antiviral Agents; Benzenesulfonates; Benzimidazoles; Cell Line; Cytomegalovirus; Drug Synergism; Humans; Ribonucleosides; STAT3 Transcription Factor; Virus Replication
PubMed: 24070820
DOI: 10.1016/j.antiviral.2013.09.011 -
BMC Infectious Diseases Jul 2013Human cytomegalovirus infections are still significant causes of morbidity and mortality in transplant recipients. The use of antiviral agents is limited by toxicity and...
BACKGROUND
Human cytomegalovirus infections are still significant causes of morbidity and mortality in transplant recipients. The use of antiviral agents is limited by toxicity and evolving resistance in immunocompromised patients with ongoing viral replication during therapy. Here, we present the first documented case of genotypic resistance against maribavir in a bone marrow transplant (BMT) recipient.
CASE PRESENTATION
The female 13-year-old patient was suffering from a refractory cytopenia. Ganciclovir, foscarnet, cidofovir, leflunomide and maribavir, an inhibitor of the cytomegalovirus UL97 protein, were administered to treat a therapy-resistant cytomegalovirus infection. Viral mutations conferring resistance against nucleotide and pyrophosphate analogs as well as maribavir (MBV) have evolved sequentially. Particularly, impressive was the fast emergence of multiple mutations T409M, H411Y and H411N conferring maribavir resistance after less than 6 weeks.
CONCLUSION
We describe the fast emergence of cytomegalovirus variants with different maribavir resistance associated mutations in a bone marrow transplant recipient treated with MBV 400 mg p.o. twice per day. The results suggest that a high virus load permitted a selection of several but distinct therapy-resistant HCMV mutants. Since a phase II study with MBV is intended for the treatment of resistant or refractory HCMV infections in transplant recipients this has to be kept in mind in patients with high viral loads during therapy (NCT01611974).
Topics: Adolescent; Antiviral Agents; Benzimidazoles; Bone Marrow Transplantation; Cytomegalovirus; Cytomegalovirus Infections; Drug Resistance, Viral; Female; Humans; Ribonucleosides
PubMed: 23870704
DOI: 10.1186/1471-2334-13-330 -
Antimicrobial Agents and Chemotherapy Jul 2013Human cytomegalovirus UL97 kinase mutations that commonly confer ganciclovir resistance cluster in different parts of the gene than those conferring resistance to...
Human cytomegalovirus UL97 kinase mutations that commonly confer ganciclovir resistance cluster in different parts of the gene than those conferring resistance to maribavir, an experimental UL97 kinase inhibitor. The drug resistance, growth, and autophosphorylation phenotypes of several unusual UL97 mutations in the kinase catalytic domain were characterized. Mutations V466G and P521L, described in clinical specimens from ganciclovir-treated subjects, conferred a UL97 kinase knockout phenotype with no autophosphorylation, a severe growth defect, and high-level ganciclovir, cyclopropavir, and maribavir resistance, similar to mutations at the catalytic lysine residue K355. Mutations F342S and V356G, observed after propagation under cyclopropavir in vitro, showed much less growth attenuation and moderate- to high-level resistance to all three drugs while maintaining UL97 autophosphorylation competence and normal cytopathic effect in cell culture, a novel phenotype. F342S is located in the ATP-binding P-loop and is homologous to a c-Abl kinase mutation conferring resistance to imatinib. UL97 mutants with relatively preserved growth fitness and multidrug resistance are of greater concern in antiviral therapy than the severely growth-impaired UL97 knockout mutants. Current diagnostic genotyping assays are unlikely to detect F342S and V356G, and the frequency of their appearance in clinical specimens remains undefined.
Topics: Antiviral Agents; Benzimidazoles; Catalytic Domain; Cell Line; Cyclopropanes; Cytomegalovirus; Cytomegalovirus Infections; Drug Resistance, Multiple; Drug Resistance, Viral; Ganciclovir; Genotype; Guanine; Humans; Mutation; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Ribonucleosides
PubMed: 23650173
DOI: 10.1128/AAC.00511-13 -
Journal of Virology Jul 2013Human cytomegalovirus (HCMV) is a common agent of congenital infection and causes severe disease in immunocompromised patients. Current approved therapies focus on...
Human cytomegalovirus (HCMV) is a common agent of congenital infection and causes severe disease in immunocompromised patients. Current approved therapies focus on inhibiting viral DNA replication. The HCMV kinase pUL97 contributes to multiple stages of viral infection including DNA replication, controlling the cell cycle, and virion maturation. Our studies demonstrate that pUL97 also functions by influencing immediate early (IE) gene expression during the initial stages of infection. Inhibition of kinase activity using the antiviral compound maribavir or deletion of the UL97 gene resulted in decreased expression of viral immediate early genes during infection. Expression of pUL97 was sufficient to transactivate IE1 gene expression from the viral genome, which was dependent on viral kinase activity. We observed that pUL97 associates with histone deacetylase 1 (HDAC1). HDAC1 is a transcriptional corepressor that acts to silence expression of viral genes. We observed that inhibition or deletion of pUL97 kinase resulted in increased HDAC1 and decreased histone H3 lysine 9 acetylation associating with the viral major immediate early (MIE) promoter. IE expression during pUL97 inhibition or deletion was rescued following inhibition of deacetylase activity. HDAC1 associates with chromatin by protein-protein interactions. Expression of active but not inactive pUL97 kinase decreased HDAC1 interaction with the transcriptional repressor protein DAXX. Finally, using mass spectrometry, we found that HDAC1 is uniquely phosphorylated upon expression of pUL97. Our results support the conclusion that HCMV pUL97 kinase regulates viral immediate early gene expression by phosphorylation-mediated disruption of HDAC1 binding to the MIE promoter.
Topics: Adaptor Proteins, Signal Transducing; Benzimidazoles; Blotting, Western; Chromatin Immunoprecipitation; Co-Repressor Proteins; Cytomegalovirus; DNA Primers; Fluorescent Antibody Technique; Gene Deletion; Gene Expression Regulation, Viral; Histone Deacetylase 1; Humans; Immediate-Early Proteins; Immunoprecipitation; Mass Spectrometry; Molecular Chaperones; Mutagenesis, Site-Directed; Nuclear Proteins; Phosphorylation; Protein Kinases; Ribonucleosides
PubMed: 23616659
DOI: 10.1128/JVI.02825-12 -
Journal of Virology Jun 2013We report a requirement for the viral protein kinase UL97 in human cytomegalovirus (HCMV) replication that maps to the ULb' region of the viral genome. A UL97-null...
We report a requirement for the viral protein kinase UL97 in human cytomegalovirus (HCMV) replication that maps to the ULb' region of the viral genome. A UL97-null (Δ97) mutant of strain TB40/E, which encodes a full-length ULb' region, exhibited replication defects, particularly in production of cell-free virus, that were more severe than those seen with a Δ97 mutant of laboratory strain AD169, which harbors extensive deletions in its ULb' region. These differences were recapitulated with additional HCMV strains by treatment with a UL97 kinase inhibitor, 1-(β-L-ribofuranosyl)-2-isopropylamino-5,6-dichlorobenzimidazole (maribavir). We observed lower levels of viral DNA synthesis and an increased requirement for UL97 in viral late gene expression in strains with full-length ULb' regions. Analysis of UL97-deficient TB40/E infections by electron microscopy revealed fewer C-capsids in nuclei, unusual viral particles in the cytoplasmic assembly compartment, and defective viral nuclear egress. Partial inhibition of viral DNA synthesis caused defects in production of cell-free virus that were up to ≈ 100-fold greater than those seen with cell-associated virus in strains TB40/E and TR, suggesting that UL97-dependent defects in cell-free virus production in strains with full-length ULb' regions were secondary to DNA synthesis defects. Accordingly, a chimeric virus in which the ULb' region of TB40/E was replaced with that of AD169 showed reduced effects of UL97 inhibition on viral DNA synthesis, late gene expression, and production of cell-free virus compared to parental TB40/E. Together, these results argue that the ULb' region encodes a factor(s) which invokes an increased requirement for UL97 during viral DNA synthesis.
Topics: Cytomegalovirus; Cytomegalovirus Infections; Gene Expression Regulation, Viral; Genome, Viral; Humans; Phosphotransferases (Alcohol Group Acceptor); Viral Proteins; Virus Replication
PubMed: 23536674
DOI: 10.1128/JVI.03477-12 -
Journal of Virology May 2013Maribavir (MBV) inhibits Epstein-Barr virus (EBV) replication and the enzymatic activity of the viral protein kinase BGLF4. MBV also inhibits expression of multiple EBV...
Maribavir (MBV) inhibits Epstein-Barr virus (EBV) replication and the enzymatic activity of the viral protein kinase BGLF4. MBV also inhibits expression of multiple EBV transcripts during EBV lytic infection. Here we demonstrate, with the use of a BGLF4 knockout virus, that effects of MBV on transcription take place primarily through inhibition of BGLF4. MBV inhibits viral genome copy numbers and infectivity to levels similar to and exceeding levels produced by BGLF4 knockout virus.
Topics: Antiviral Agents; Benzimidazoles; Cell Line; Down-Regulation; Epstein-Barr Virus Infections; Gene Expression Regulation, Viral; Genome, Viral; Herpesvirus 4, Human; Humans; Protein Serine-Threonine Kinases; Ribonucleosides; Viral Proteins; Virus Replication
PubMed: 23449792
DOI: 10.1128/JVI.03505-12 -
American Journal of Transplantation :... Nov 2012Maribavir is an oral benzimidazole riboside with potent in vitro activity against cytomegalovirus (CMV), including some CMV strains resistant to ganciclovir. In a... (Comparative Study)
Comparative Study Randomized Controlled Trial
Efficacy and safety of maribavir dosed at 100 mg orally twice daily for the prevention of cytomegalovirus disease in liver transplant recipients: a randomized, double-blind, multicenter controlled trial.
Maribavir is an oral benzimidazole riboside with potent in vitro activity against cytomegalovirus (CMV), including some CMV strains resistant to ganciclovir. In a randomized, double-blind, multicenter trial, the efficacy and safety of prophylactic oral maribavir (100 mg twice daily) for prevention of CMV disease were compared with oral ganciclovir (1000 mg three times daily) in 303 CMV-seronegative liver transplant recipients with CMV-seropositive donors (147 maribavir; 156 ganciclovir). Patients received study drug for up to 14 weeks and were monitored for CMV infection by blood surveillance tests and also for the development of CMV disease. The primary endpoint was Endpoint Committee (EC)-confirmed CMV disease within 6 months of transplantation. In a modified intent-to-treat analysis, the noninferiority of maribavir compared to oral ganciclovir for prevention of CMV disease was not established (12% with maribavir vs. 8% with ganciclovir: event rate difference of 0.041; 95% CI: -0.038, 0.119). Furthermore, significantly fewer ganciclovir patients had EC-confirmed CMV disease or CMV infection by pp65 antigenemia or CMV DNA PCR compared to maribavir patients at both 100 days (20% vs. 60%; p < 0.0001) and at 6 months (53% vs. 72%; p = 0.0053) after transplantation. Graft rejection, patient survival, and non-CMV infections were similar for maribavir and ganciclovir patients. Maribavir was well-tolerated and associated with fewer hematological adverse events than oral ganciclovir. At a dose of 100 mg twice daily, maribavir is safe but not adequate for prevention of CMV disease in liver transplant recipients at high risk for CMV disease.
Topics: Acyclovir; Administration, Oral; Antiviral Agents; Benzimidazoles; Cytomegalovirus Infections; Dose-Response Relationship, Drug; Double-Blind Method; Drug Administration Schedule; Female; Follow-Up Studies; Ganciclovir; Graft Rejection; Graft Survival; Humans; Liver Transplantation; Male; Postoperative Complications; Prospective Studies; Ribonucleosides; Risk Assessment; Treatment Outcome
PubMed: 22947426
DOI: 10.1111/j.1600-6143.2012.04231.x -
Antiviral Research Aug 2012Resistance to the experimental human cytomegalovirus (CMV) UL97 kinase inhibitor maribavir has been mapped to UL97 mutations at codons 353, 397, 409 and 411, in the...
Resistance to the experimental human cytomegalovirus (CMV) UL97 kinase inhibitor maribavir has been mapped to UL97 mutations at codons 353, 397, 409 and 411, in the kinase ATP-binding region, and to mutations in the UL27 gene. We studied the maribavir susceptibility phenotypes of additional UL97 mutations observed in vitro and in clinical trials, and the effect of simultaneous mutation in both UL97 and UL27. In vitro selection under maribavir identified a new locus of UL97 mutation within the conserved kinase p-loop (L337M), which conferred low grade maribavir resistance (3.5-fold increased EC50) without ganciclovir cross-resistance. During maribavir Phase III CMV prevention clinical trials, three previously unknown UL97 sequence variants were detected in plasma samples after 27-98 days of drug exposure (I324V, S334G and S386L). These variants did not confer any drug resistance despite proximity to mutations that confer maribavir resistance. The UL27 resistance mutation R233S, when added to strains containing UL97 mutations L337M or V353A, doubled their maribavir EC50s. These results expand the range of UL97 maribavir-resistance mutations into another part of the kinase ATP-binding region, but offer no genotypic evidence that development of drug resistance affected the outcomes of Phase III maribavir clinical trials after drug exposure of up to 14 weeks. There is a potential for increased maribavir resistance in UL27-UL97 double mutants.
Topics: Antiviral Agents; Benzimidazoles; Clinical Trials, Phase III as Topic; Cytomegalovirus; Cytomegalovirus Infections; Drug Resistance, Viral; Humans; Mutation, Missense; Phosphotransferases (Alcohol Group Acceptor); Ribonucleosides
PubMed: 22664236
DOI: 10.1016/j.antiviral.2012.05.013