Duck hepatitis B photoinactivation by dimethylmethylene blue in RBC suspensions

BACKGROUND: Dimethylmethylene blue (DMMB) has been used to photoinactivate a number of model viruses, including VSV, in RBC suspensions under conditio ns that preserve in vitro RBC properties during storage.(23) The relative s ensitivity of duck HBV (DHBV) and VSV to photoinactivation by DMMB was inve stigated by performing an indirect immunofluorescence assay (IFA) using pri mary duck hepatocyte (PDH) cultures or a standard plaque assay for the resp ective viruses. STUDY DESIGN AND METHODS: DMMB was added to 45-percent Hct, WBC-reduced, ox ygenated AS-3 RBCs at 10-, 1-, and 0.1-muM concentrations. Samples (1-mm th ick) were illuminated with 5.4-mW per cm(2) of red light for 2 or 9 seconds . Unilluminated samples without DMMB or with 10 muM DMMB served as control. RESULTS: DHBV and VSV were rapidly photoinactivated by DMMB in a concentrat ion- and light-dose-dependent fashion. Neither virus was substantially inac tivated by incubation with DMMB in the dark. For a given light exposure, DH BV required a concentration of DMMB one-one hundredth that of VSV to achiev e approximately the same level of inactivation. CONCLUSION: DHBV appears to be considerably more sensitive than VSV to DMMB photoinactivation. Photoinactivation in 45-percent Hct RBCs can be achieve d in seconds by using micromolar quantities of dye.