Dengue virus infection induces passive release of high mobility group box 1 protein by epithelial cells

Objectives: Dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS) are severe complications of secondary dengue virus (DV) infection. In the current study, we provide the first evidence of induction of cellular necrosis by DV type 2 (DV-2). Methods and Results: The epithelial cell line A549 can support replication of dengue virus as demonstrated by expression of viral NS1 antigen and virus plaque assay. DV-2 infection of cells induced cell death in approximately half of the cells that were actively infected. Using sodium 3'-[1-(phenylaminocarbonyl)-3, 4-tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate [XTT]-based cell viability assays, we found that DV-2 infection at a multiplicity of infection (MOI) of 10 resulted in significant death of cells as well as high extracellular lactate dehydrogenase (LDH) activity and leakage of the high mobility group 1 (HMGB1) protein into the extracellular space. Conclusions: These results suggest that HMGB1 may be a signal of tissue or cellular injury by DV-2, which in turn is likely to induce and/or enhance an immune reaction. (C) 2007 The British Infection Society. Published by Elsevier Ltd. All rights reserved.