Inactivation of WBCs in RBC suspensions by photoactive phenothiazine dyes: comparison of dimethylmethylene blue and MB.

BACKGROUND: The transfusion of blood components containing WBCs can cause unwanted complications, which include virus transmission, transfusion-associated GVHD, alloimmunization, febrile reactions, and immunomodulation. Phototreatment with 4 microM of dimethylmethylene blue (DMMB) and 13 J per cm(2) of white light irradiation has previously been shown to be an effective way to inactivate different models of enveloped and nonenveloped viruses in RBC suspensions, with minimum damage to RBCs. The present study compares WBC photoinactivation in buffy coat after DMMB or MB phototreatment under virucidal conditions. STUDY DESIGN AND METHODS: Buffy coat diluted to 30-percent Hct was treated with the dye and white light. Isolated WBCs were assayed for cell proliferation and viability by an assay using a tetrazolium compound, limiting dilution analysis, DNA fragmentation, and flow cytometry assays. RESULTS: DMMB and 2.5 J per cm(2) of light phototreatment can inactivate T cells to the limit of detection by limiting dilution analysis (>4.76 log reduction). No WBC proliferation activity was observed after DMMB and 3.8 J per cm(2) of light. DNA degradation after DMMB phototreatment was light dependent. In addition, DMMB phototreatment induced apoptosis in WBCs. In contrast, MB phototreatment under virucidal conditions did not cause significant changes in the viability of WBCs. Neither DNA degradation nor signs of apoptosis were observed after MB phototreatment. CONCLUSION: DMMB phototreatment inactivates T-lymphocytes, the cells that cause GVHD.

[A promising method for preparative production and purification of the Marburg virus]. / Perspektivnyi metod preparativnoi narobotki i ochistki virusa Marburg.

A method for the production of Marburg virus in preparative amounts has been developed. It is based on sedimentation of the virus from blood plasma of infected guinea pigs by ultracentrifugation followed by purification in sucrose density gradient or gel chromatography on macroporous glass sorbents. The optimal terms of blood collection in infected animals were determined. Purified virus did not lose its biological activity. Concentrated virus preparations were studied by electron microscopy and polyacrylamide gel electrophoresis.

[Marburg virus and mononuclear phagocytes: study of interactions]. / Virus marburg i mononuklearnye fagotsity: izuchenie vzaimodeistviia.

Interactions of Marburg virus and mononuclear phagocytes of guinea pigs were studied using a complex of virologic methods and electron microscopy. Active reproduction of Marburg virus in peritoneal macrophages both in vitro and in vivo was revealed. The study showed that mononuclear phagocytes were the first target cells in guinea pigs intraperitoneally infected with Marburg virus which provided virus dissemination into interstitial tissue of viscera. Analysis of the results indicates an important role of viral alteration of mononuclear phagocytes in the pathogenesis of Marburg disease.

[A comparative study of the in-vitro interaction of the Marburg virus with macrophages from different animal species]. / Sravnitel'noe izuchenie vzaimodeistviia virusa Marburg s makrofagami razlichnykh vidov zhivotnykh in vitro.

The amplification of Marburg virus in primary cultures of peritoneal macrophages of animals with different sensitivity to infection with this virus, as well as the capacity of this virus to adsorb on macrophages were studied. Macrophages of the animals sensitive to Marburg virus were capable to support its reproduction in vitro whereas those of resistant animals were not. Macrophages of the animals with intermediate sensitivity were shown to be either completely resistant to virus reproduction or to delay it. Besides, macrophages of sensitive and insensitive animals were capable to adsorb this virus, this capacity being markedly reduced in macrophages isolated from immunized animals and those sensitive animals which developed the disease after inoculation of the virus. The authors conclude that animal susceptibility to Marburg virus in vivo correlated with the capacity of macrophages to support Marburg virus reproduction in vitro and not with the capacity of the virus to adsorb on the macrophage surface. It is suggested that the evaluation of Marburg virus amplification in macrophages could be used as a criterion for evaluation of the susceptibility of animals to this virus in vivo.