Phenotypic and genotypic characterization of induced acyclovir-resistant clinical isolates of herpes simplex virus type 1.
Eleven strains of acyclovir (ACV)-resistant herpes simplex virus type 1 (HSV-1) were generated from HSV-1 clinical isolates by exposure to ACV. Genotype of the thymidine kinase (TK) and DNA polymerase (pol) genes from these mutants were further analyzed. Genotypic analysis revealed four non-synonymous mutations in TK gene associated with gene polymorphism and two to three non-synonymous mutations in DNA pol gene. Seven and six strains contained at least one resistance-associated mutation at TK and DNA pol gene, respectively. Resistance-associated mutations within the TK gene consisted of 64% of non-synonymous frameshift mutations within the homopolymer region of G's and C's, and 36% of non-synonymous nucleotide substitutions of the conserved gene region (C336Y, R51W and R222H), nucleotide that produced stop codon (L288Stop) and two amino acid substitutions outside the conserved region (E39G & L208F). There were 10 non-synonymous amino acid substitutions located outside the conserved region with the unclear significance to confer resistance observed. Resistance-associated mutations in DNA pol gene include insertion of G at the homopolymer region of G's (794-797) and amino acid substitutions inside (V621S) or outside (H1228D) the conserved region. In silico analysis of the mutated TK (C336Y, R51W and L208F), and DNA pol (V621S and H1228D) suggested structural changes that might alter the stability of these proteins. However, there were several mutations with unclear significance to confer ACV-resistance identified, especially mutations outside the conserved region.
School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia; Pathology Department, Hospital Lahad Datu, 91110 Lahad Datu, Sabah, Malaysia.
Ainulkhir
A
Hussin
Norefrina Shafinaz
NS
Md Nor
Nazlina
N
Ibrahim
D000212:Acyclovir / Q000494:pharmacology*; D000998:Antiviral Agents / Q000494:pharmacology*; D004252:DNA Mutational Analysis; D024882:Drug Resistance, Viral; D006561:Herpes Simplex / Q000821:virology*; D018259:Herpesvirus 1, Human / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D012641:Selection, Genetic; D012692:Serial Passage; D014764:Viral Proteins / Q000235:genetics; D014776:Virus Cultivation
D000998:Antiviral Agents; D014764:Viral Proteins; D000212:Acyclovir
Acyclovir; DNA polymerase; Frameshift; HSV-1; Herpes simplex virus type 1; Thymidine kinase