title: Dimethyl sulfoxide blocks herpes simplex virus-1 productive infection in vitro acting at different stages with positive cooperativity. Application of micro-array analysis.
abstract: BACKGROUND
  Dimethyl sulfoxide (DMSO) is frequently used at a concentration of up to 95% in the formulation of antiherpetic agents because of its properties as a skin penetration enhancer. Here, we have analyzed the effect of DMSO on several parameters of Herpes Simplex Virus replication.
  
  
  METHODS
  Productive infection levels of HSV-1 were determined by plaque assay or by reporter gene activity, and its DNA replication was estimated by PCR. Transcript levels were evaluated with HSV-specific DNA micro-arrays.
  
  
  RESULTS
  DMSO blocks productive infection in vitro in different cell types with a 50% inhibitory concentration (IC50) from 0.7 to 2% depending upon the multiplicity of infection. The concentration dependence exhibits a Hill coefficient greater than 1, indicating that DMSO blocks productive infection by acting at multiple different points (mechanisms of action) with positive cooperativity. Consistently, we identified at least three distinct temporal target mechanisms for inhibition of virus growth by DMSO. At late stages of infection, DMSO reduces virion infectivity, and markedly inhibits viral DNA replication. A third mode of action was revealed using an oligonucleotide-based DNA microarray system for HSV. These experiments showed that DMSO reduced the transcript levels of many HSV-1 genes; including several genes coding for proteins involved in forming and assembling the virion. Also, DMSO markedly inhibited some but not all early transcripts indicating a previously unknown mode for inhibiting the early phase of HSV transcription-replication cycle.
  
  
  CONCLUSIONS
  These observations suggest that DMSO itself may have a role in the anti-herpetic activity of formulations utilizing it as a dispersant.
authors.affiliation: Dept. of Mol. Biol. & Biochem, U. Calif. Irvine, 19172 Jamboree Road, Irvine, CA 92697, USA. jsaguila@uci.edu
authors.forename: J S
authors.initials: JS
authors.lastname: Aguilar
authors.forename: D
authors.initials: D
authors.lastname: Roy
authors.forename: P
authors.initials: P
authors.lastname: Ghazal
authors.forename: E K
authors.initials: EK
authors.lastname: Wagner
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004261:DNA Replication / Q000187:drug effects*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology* / Q000627:therapeutic use; D006561:Herpes Simplex / Q000188:drug therapy; D018259:Herpesvirus 1, Human / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D011817:Rabbits; D014709:Vero Cells; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D004121:Dimethyl Sulfoxide