title: Thiazole orange, a DNA-binding photosensitizer with flexible structure, can inactivate pathogens in red blood cell suspensions while maintaining red cell storage properties.
abstract: BACKGROUND
  Development of a robust pathogen reduction system for red cells (RBCs) utilizing photosensitive dyes has been constrained by hemolysis, usually mediated by reactive oxygen species emanating from dye free in solution as well as dye bound to the RBC membrane. The RBC binding properties of thiazole orange (TO), a flexible nucleic acid intercalating cyanine dye that predominantly acts as a photosensitizer only when bound, were assessed along with its virucidal, bactericidal, and light-induced hemolytic activities.
  
  
  METHODS
  Leukodepleted 20% hematocrit RBCs suspended in Erythrosol (RAS-2) were oxygenated, inoculated with test organisms, incubated with TO, and illuminated. Control and treated samples were analyzed by appropriate assay. Identically prepared, but uncontaminated samples were phototreated, concentrated to 45% hematocrit, and assayed for potassium leakage, hemolysis, and ATP during storage.
  
  
  RESULTS
  Approximately 21 percent TO bound to RBCs. Phototreatment inactivated from 5.4 to 7.1 log(10) of 5 tested viruses and from 2.3 to greater than 7.0 log(10) of 8 tested bacteria. Phototreated RBCs exhibited only slightly increased hemolysis, moderately elevated potassium efflux, and similar levels of ATP compared to controls.
  
  
  CONCLUSIONS
  TO can photoinactivate several model viruses and pathogens in RBCs under conditions that produce limited hemolysis without the addition of quenchers or competitive inhibitors.
authors.affiliation: American Red Cross Biomedical Services, Holland Laboratory, Blood Components Development, Rockville, Maryland 20855, USA. skripcha@usa.redcross.org
authors.forename: Andrey
authors.initials: A
authors.lastname: Skripchenko
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wagner
authors.forename: Dedeene
authors.initials: D
authors.lastname: Thompson-Montgomery
authors.forename: Helen
authors.initials: H
authors.lastname: Awatefe
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism; D001424:Bacterial Infections / Q000517:prevention & control; D052160:Benzothiazoles; D001667:Binding, Competitive; D001793:Blood Preservation; D017848:Blood-Borne Pathogens; D015925:Cryopreservation; D004269:DNA, Bacterial / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004912:Erythrocytes / Q000166:cytology / Q000382:microbiology*; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D050296:Microbial Viability / Q000187:drug effects; D017319:Photosensitizing Agents / Q000737:chemistry*; D011804:Quinolines; D013844:Thiazoles / Q000737:chemistry* / Q000378:metabolism; D014777:Virus Diseases / Q000517:prevention & control; D038301:Virus Inactivation / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D052160:Benzothiazoles; D004269:DNA, Bacterial; D004279:DNA, Viral; D005456:Fluorescent Dyes; D017319:Photosensitizing Agents; D011804:Quinolines; D013844:Thiazoles; C051000:thiazole orange