Measles Virus Infects and Programs MAIT Cells for Apoptosis.

Measles virus (MeV) binds, infects and kills CD150+ memory T-cells, leading to "immune amnesia". Whether MeV targets innate, memory-like T-cells is unknown. We demonstrate that human peripheral blood and hepatic MAIT and iNKT cells express surprisingly high levels of CD150, more than any other lymphocyte subsets, including central and effector memory T-cells. Furthermore, exposing MAIT cells to MeV results in their efficient infection and rapid apoptosis. This constitutes the first report of direct MAIT cell infection by a viral pathogen. Given MAIT cells' antimicrobial properties, their elimination by MeV may contribute to measles-induced immunosuppression and heightened vulnerability to unrelated infections.