The Lack of Maturation of Ebola Virus-Infected Dendritic Cells Results from the Cooperative Effect of at Least Two Viral Domains

Departments of Pathology and.
Journal of Virology (Impact Factor: 4.44). 04/2013; 87(13). DOI: 10.1128/JVI.03316-12
Source: PubMed


Ebola virus (EBOV) infections are characterized by deficient T lymphocyte responses, T lymphocyte apoptosis and lymphopenia, in the absence of direct infection of lymphocytes. In contrast, dendritic cells (DC) are infected but fail to mature appropriately, thereby impairing the T cell response. We investigated the contribution of EBOV proteins in modulating DC maturation by generating recombinant viruses expressing enhanced green fluorescent protein and carrying mutations affecting several potentially immunomodulating domains. These included envelope glycoprotein (GP) domains as well as innate response antagonist domains (IRADs) previously identified in the VP24 and VP35 proteins. GP expressed by an unrelated vector, but not the wild-type EBOV, was found to strongly induce DC maturation, and infections with recombinant EBOV carrying mutations disabling GP functional domains did not restore DC maturation. In contrast, each of the viruses carrying mutations disabling any IRAD in VP35 induced a dramatic upregulation of DC maturation markers. This was dependent on infection, but not interaction with GP. Disabling of IRADs also resulted in a several hundred fold increase in secretion of cytokines and chemokines. Furthermore, these mutations induced formation of homotypic DC clusters, which represent close correlates of their maturation, and presumably facilitate transfer of antigen from migratory DC to lymph node DC. Thus, an individual IRAD is insufficient to suppress DC maturation; rather, the suppression of DC maturation and the "immune paralysis" observed during EBOV infections results from a cooperative effect of two or more individual IRADs.

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