PRESERVATION OF RED-CELL PROPERTIES AFTER VIRUCIDAL PHOTOTREATMENT WITH DIMETHYLMETHYLENE BLUE

BACKGROUND: All published reports have described methods for virus pho toinactivation which significantly alter red cell (RBC) properties dur ing storage. In order to improve virucidal activity and reduce damage to RBCs, a series of phenothiazine derivatives were either synthesized or purified and screened for bacteriophage inactivation and red cell potassium efflux. One compound, 1,9-dimethylmethylene blue (dimethyl-m ethylene blue), had superior screening results and was chosen for furt her characterization. STUDY DESIGN AND METHODS:White cell reduced RBC suspensions (30% hematocrit) were deliberately in oculated with extrac ellular virus or virus-infected VERO cells, incubated with 4 mu M dime thyl-methylene blue and illuminated with cool-white fluorescent light. Control and treated samples were titered for virus inactivation. In p ar allel studies, RBC suspensions were exposed to dimethylmethylene bl ue and light under identical conditions and assayed for in vitro RBC s torage properties. RESULTS: Phototreatment of RBC suspensions inactiva ted >4.4 log(10) of extracellular vesicular stomatitis virus (VSV), >3 .0 log(10) of intracellular VSV, >5.0 log(10) of extracellular pseudor abies virus (PRV), >4.8 log(10) of intracellular PRV, >4.7 log(10) of extra-cellular bovine virus diarrhea virus, 5.8 log(10) of bacterio-ph age phi 6 and >7 log(10) of bactariophage R17. Encephalo-myocarditis v irus, a nonenveloped picornavirus, was resistant to photoinactivation. Virucidal conditions resulted in no detectable IgG binding in 11 of 1 3 samples, unchanged RBC morphology, normal banding patterns of RBC me mbrane proteins on SDS PAGE, and unaltered characteristics of 12 of 13 RBC antigens during storage as measured by antibody titrations. In ad dition, minimal changes were observed in RBC osmotic fragility, lysis, potassium efflux, ATP and 2,3-DPG levels: and the strength of one RBC antigen during storage of phototreated samples compared with controls . CONCLUSION: Dimethylmethylene blue photo-treatment can inactivate se veral intracellular and extracellular model viruses under conditions w hich minimally alter RBC properties during 42 day storage at 1-6 degre es C.