Lena Fischer1, Eike Imrich1, Kerstin Laib Sampaio2, Jörg Hofmann3, Gerhard Jahn1, Klaus Hamprecht1, Katharina Göhring4. 1. Institute of Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, 72076 Tübingen, Germany. 2. Institute of Virology, University Hospital Ulm, 89081 Ulm, Germany. 3. Institute of Medical Virology, Charité University Hospital, 10117 Berlin, Germany; Labor Berlin, Charité-Vivantes GmbH, 13353 Berlin, Germany. 4. Institute of Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, 72076 Tübingen, Germany. Electronic address: katharina.goehring@med.uni-tuebingen.de.
Abstract
BACKGROUND: Human cytomegalovirus (HCMV) drug-resistance remains of high clinical importance. While UL97-mutations can confer ganciclovir-resistance, UL54-mutations can be associated with resistance to ganciclovir, foscarnet and/or cidofovir. OBJECTIVE: Three UL97-mutations (A619V, P468Q, del597-599), three UL54-mutations (V715A, A492D, L516W) and two UL97/UL54-mutation combinations (A594TUL97+V715MUL54; A591VUL97+D515EUL54, L516MUL54, I521TUL54) were characterised phenotypically. All mutations were introduced into the bacterial artificial chromosome (BAC) TB40-BACKL7-UL32EGFP. A revertant of HCMV-TB40-BACKL7-UL32EGFP/A591VUL97+D515EUL54, L516MUL54, I521TUL54 was generated. RESULTS: The UL97-mutation del597-599 showed GCV-resistance while A619V and P468Q were drug-sensitive. The UL54-mutation V715A was FOS-resistant/CDV-hypersensitive and L516W was GCV/CDV cross-resistant. Mutation A594TUL97+V715MUL54 showed GCV/FOS cross-resistance. HCMV-BACKL7-UL32EGFP/A591VUL97+D515EUL54,L516MUL54, I521TUL54 was GCV/CDV cross-resistant with a remarkably increased GCV-ratio compared to a strain where only the UL54-mutations D515E+L516M+I521T were present. Since the revertant was drug-sensitive again, the increased drug-ratio is supposed to be due to the UL97-polymorphism A591V. CONCLUSION: Phenotypic characterisation of newly detected mutations in UL97 and UL54 remain of high importance. Only mutations with a confirmed phenotype allow reliable interpretation of genotypic methods. Here, we provide the first description of a UL97-polymorphism that contributes to the overall drug-resistance when combined with resistance-associated UL54-mutations. The finding shows the high importance to look at mutations in the context of their genetic background.
BACKGROUND:Human cytomegalovirus (HCMV) drug-resistance remains of high clinical importance. While UL97-mutations can confer ganciclovir-resistance, UL54-mutations can be associated with resistance to ganciclovir, foscarnet and/or cidofovir. OBJECTIVE: Three UL97-mutations (A619V, P468Q, del597-599), three UL54-mutations (V715A, A492D, L516W) and two UL97/UL54-mutation combinations (A594TUL97+V715MUL54; A591VUL97+D515EUL54, L516MUL54, I521TUL54) were characterised phenotypically. All mutations were introduced into the bacterial artificial chromosome (BAC) TB40-BACKL7-UL32EGFP. A revertant of HCMV-TB40-BACKL7-UL32EGFP/A591VUL97+D515EUL54, L516MUL54, I521TUL54 was generated. RESULTS: The UL97-mutation del597-599 showed GCV-resistance while A619V and P468Q were drug-sensitive. The UL54-mutation V715A was FOS-resistant/CDV-hypersensitive and L516W was GCV/CDV cross-resistant. Mutation A594TUL97+V715MUL54 showed GCV/FOS cross-resistance. HCMV-BACKL7-UL32EGFP/A591VUL97+D515EUL54,L516MUL54, I521TUL54 was GCV/CDV cross-resistant with a remarkably increased GCV-ratio compared to a strain where only the UL54-mutations D515E+L516M+I521T were present. Since the revertant was drug-sensitive again, the increased drug-ratio is supposed to be due to the UL97-polymorphism A591V. CONCLUSION: Phenotypic characterisation of newly detected mutations in UL97 and UL54 remain of high importance. Only mutations with a confirmed phenotype allow reliable interpretation of genotypic methods. Here, we provide the first description of a UL97-polymorphism that contributes to the overall drug-resistance when combined with resistance-associated UL54-mutations. The finding shows the high importance to look at mutations in the context of their genetic background.