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Basic Characteristics of Mutations
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Mutation Site
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Q228H |
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Mutation Site Sentence
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The remaining 5 sequence variants (L134V, S227I, Q228H, R410G, and D414N) were shown to be inert with regard to letermovir susceptibility, thus representing natural polymorphisms. |
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Mutation Level
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Amino acid level |
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Mutation Type
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Nonsynonymous substitution |
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Gene/Protein/Region
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UL56 |
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Standardized Encoding Gene
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UL56
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Genotype/Subtype
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- |
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Viral Reference
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FJ527563
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Functional Impact and Mechanisms
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Disease
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Cytomegalovirus infections
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Immune
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- |
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Target Gene
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-
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Clinical and Epidemiological Correlations
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Clinical Information
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Y |
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Treatment
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- |
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Location
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- |
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Literature Information
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PMID
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26113373
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Title
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Characterization of Cytomegalovirus Breakthrough Events in a Phase 2 Prophylaxis Trial of Letermovir (AIC246, MK 8228)
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Author
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Lischka P,Michel D,Zimmermann H
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Journal
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The Journal of infectious diseases
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Journal Info
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2016 Jan 1;213(1):23-30
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Abstract
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BACKGROUND: The efficacy of different letermovir (AIC246, MK8228) doses (60, 120, and 240 mg/day) against human cytomegalovirus (HCMV) was evaluated in a recent phase 2b dose-range-finding prophylaxis study in stem-cell transplant recipients. Here we report the genotypic and phenotypic characterization of 15 viral breakthroughs considered to be virological failures. METHODS: Direct sequencing of an HCMV open reading frame UL56 region that included amino acids 230-370 and thus encompassed all known letermovir resistance mutations was followed by marker-transfer experiments to assess the impact of the identified sequence polymorphisms on viral fitness and susceptibility to letermovir. RESULTS: UL56 genotyping was successful for 12 of 15 patients. Six amino acid substitutions were detected in 5 patients. In 1 subject from the 60-mg-dose group, the known letermovir resistance mutation V236M was identified subsequent to a wild-type viremic episode. The remaining 5 sequence variants (L134V, S227I, Q228H, R410G, and D414N) were shown to be inert with regard to letermovir susceptibility, thus representing natural polymorphisms. CONCLUSIONS: Our findings represent the first case of a letermovir resistance mutation emerging in the clinic, apparently because of a suboptimal prophylactic dose (60 mg/day). This is in agreement with the trial's efficacy analyses, findings of which suggest that letermovir doses of 60 mg/day and 120 mg/day are suboptimal for prophylaxis whereas a dose of 240 mg/day appears to achieve complete suppression of viremia.
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Sequence Data
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-
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