Heterogeneity and evolution of thymidine kinase and DNA polymerase mutants of herpes simplex virus type 1 (HSV-1): implications for antiviral therapy.

Laboratory of Virology, Rega Institute for Medical Research, KU Leuven, Belgium.
The Journal of Infectious Diseases (Impact Factor: 5.78). 01/2013; DOI: 10.1093/infdis/jit019
Source: PubMed

ABSTRACT Background. Infections caused by acyclovir resistant isolates of herpes simplex virus (HSV) are an emerging concern after hematopoietic stem cell transplantation (HSCT). Understanding evolutionary aspects of HSV infection is crucial to the design of effective therapeutic and control strategies.Methods. Eight sequential HSV-1 isolates were recovered from a HSCT patient who suffered from recurrent herpetic gingivostomatitis and was treated alternatively with acyclovir, ganciclovir, and foscavir. The diverse spectra and temporal changes of HSV drug resistance were determined phenotypically (drug-resistance profiling) and genotypically (sequencing of the viral thymidine kinase and DNA polymerase genes).Results. Analysis of sixty clones recovered from the different isolates demonstrated that most of these isolates were heterogeneous mixtures of variants indicating the simultaneous infection with different drug-resistant viruses. The phenotype/genotype of several clones associated with resistance to acyclovir and/or foscavir were identified. Two novel mutations (E798 K and I922T) in the viral DNA polymerase could be linked to drug-resistance.Conclusions. The heterogeneity within the viral populations and the temporal changes of drug-resistant viruses found in this HSCT recipient were remarkable, showing a rapid evolution of HSV-1. Drug-resistance surveillance is highly recommended among immunocompromised patients to manage the clinical syndrome and to avoid the emergence of multi-drug resistant isolates.

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