Measles immunity and immunosuppression

•Measles virus replication in lymphoid tissue uses CD150 as a B and T cell receptor.•Persistent RNA in lymphoid tissue is associated with generation of durable immunity.•Germinal centers and numbers of peripheral Tfh cells and antibody-secreting cells increase for months.•Increased susceptibility to other infections continues for years after apparent recovery.•Memory and naïve B cells are depleted and diversity of pre-existing antibodies is reduced. Effects of measles on the immune system are only partially understood. Lymphoid tissue is a primary site of measles virus (MeV) replication where CD150 is the receptor for infection of both B and T cells. Lymphocyte depletion occurs during the acute phase of infection, but initiation of the adaptive immune response leads to extensive lymphocyte proliferation, production of MeV-specific antibody and T cells, the rash and clearance of infectious virus. Viral RNA persists in lymphoid tissue accompanied by ongoing germinal center proliferation, production of antibody-secreting cells, functionally distinct populations of T cells and antibody avidity maturation to establish life-long immunity. However, at the same time diversity of pre-existing antibodies and numbers of memory and naive B cells are reduced and susceptibility to other infections is increased.