title: Rapid detection and quantitation of ganciclovir resistance in cytomegalovirus quasispecies.
abstract: Human cytomegalovirus (HCMV) may cause severe or fatal disease among immunocompromised patients. The first line prophylaxis and systemic HCMV disease therapy is ganciclovir (GCV). The presence of GCV-resistant virus has been linked to fatal HCMV disease. The implementation of rapid and sensitive techniques for the early detection and monitoring of GCV-resistance may be helpful to support antiviral therapy management. A pyrosequencing assay for the detection and quantitation of the most frequent mutations conferring moderate- and high-grade GCV resistance was implemented. The pyrosequencing achieved an analytical sensitivity for adequate interpretation of ≥10(3)  copies/ml. The assay was validated with 18 whole blood samples taken over a 6-month period from an umbilical cord blood recipient infected persistently with HCMV and allowed the detection and monitoring of the M460I and A594V GCV-resistant mutations. The percentage of resistant quasispecies ranged from 7.9% to 55.2% for the M460I mutation and from 19.8% to 43% for the A594V mutation. Clearance of the M460I mutation occurred in parallel with a decrease in the HCMV viremia, while the A594V mutation persisted. The pyrosequencing method for detection of GCV is sensitive enough to be used directly on clinical samples for the early identification of resistance mutations and allows the quantitation of resistant and wild type virus quasispecies within hours. The quantitation of minor resistant variants is an important issue to understand their relationship with viral load modification, and potentially anticipate treatment adjustment.
authors.affiliation: Servicio de Microbiología y Parasitología Clínica, Hospital Universitario La Paz, IdiPaz, Madrid, Spain. guillermo.ruiz@salud.madrid.org
authors.forename: Guillermo
authors.initials: G
authors.lastname: Ruiz-Carrascoso
authors.forename: María Pilar
authors.initials: MP
authors.lastname: Romero-Gómez
authors.forename: Diego
authors.initials: D
authors.lastname: Plaza
authors.forename: Jesús
authors.initials: J
authors.lastname: Mingorance
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003587:Cytomegalovirus / Q000187:drug effects*; D003586:Cytomegalovirus Infections / Q000821:virology*; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D024882:Drug Resistance, Viral; D005260:Female; D015774:Ganciclovir / Q000494:pharmacology*; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests / Q000379:methods; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D008969:Molecular Sequence Data; D009154:Mutation; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D015774:Ganciclovir
keywords: UL97 gene; antiviral drug resistance; ganciclovir; human cytomegalovirus; pyrosequencing