Mechanism of measles virus-induced suppression of inflammatory immune responses

Measles virus (MV) causes profound immunosuppression, resulting in high inf ant mortality. The mechanisms are poorly understood, largely due to the lac k of a suitable animal model. Here, we report that particular MV proteins, in the absence of MV replication, could generate a systemic immunosuppressi on in mice through two pathways: (1) via MV-nucleoprotein and its receptor Fc gammaR on dendritic cells; and (2) via virus envelope glycoproteins and the MV-hemagglutinin cellular receptor, CD46. The effects comprise reduced hypersensitivity responses associated with impaired function of dendritic c ells, decreased production of IL-12, and the loss of antigen-specific T cel l proliferation. These results introduce a novel model for testing the immu nosuppressive potential of anti-measles vaccines and reveal a specific mech anism of MV-induced modulation of inflammatory reactions.