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Antimicrobial Agents and Chemotherapy, October 1999, p. 2412-2416, Vol. 43, No. 10
Laboratoire de Virologie des Hospices Civils
de Lyon,
Received 8 March 1999/Returned for modification 17 May
1999/Accepted 6 August 1999
Varicella-zoster virus (VZV) is a common herpesvirus responsible
for disseminated or chronic infections in immunocompromised patients.
Effective drugs such as acyclovir (ACV), famciclovir (prodrug of
penciclovir), and foscarnet are available to treat these infections.
Here we report the phenotypic and genetic characterization of four
ACV-resistant VZV strains isolated from AIDS patients and transplant
recipients. Sensitivity to six antiviral drugs was determined by an
enzyme-linked immunosorbent assay, viral thymidine kinase (TK) activity
was measured by comparing [3H]thymidine and
1-
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Phenotypic and Genetic Characterization of
Thymidine Kinase from Clinical Strains of Varicella-Zoster
Virus Resistant to Acyclovir
-D-arabinofuranosyl-[3H]thymine as
substrates, and the TK gene open reading frame was sequenced. Three
strains were found to be TK deficient, and the fourth was a mixed
population composed of TK-positive and TK-deficient viruses. Each
strain presented a unique TK gene mutation that could account for ACV
resistance. In one strain, the deletion of two nucleotides at codon 215 induced a premature stop signal at codon 217. In another strain, a
single nucleotide addition at codon 167 resulted in a premature stop
signal at codon 206. In both other strains, we identified amino acid
substitutions already described in other ACV-resistant VZV strains:
either Glu
Gly at residue 48 or Arg
Gly at residue 143. According
to our work and data previously reported on resistant VZV strains,
there are three areas in the TK gene where 71% of the mutations
described to date are located. These areas are putative candidates for
a genotypic diagnosis of ACV resistance.
*
Corresponding author. Mailing address: Laboratoire de
Virologie des Hospices Civils de Lyon, 8 avenue Rockefeller, 69373 Lyon Cedex 08, France. Phone: 33 478777029. Fax: 33 478014887. E-mail: fmorfin{at}rockefeller.univ-lyon1.fr.
Antimicrobial Agents and Chemotherapy, October 1999, p. 2412-2416, Vol. 43, No. 10
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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