Murine leukemia virus targets innate-like B1 B cells to establish infection in mice

Background Retroviruses are believed to efficiently spread via sites of cell-cell contact designated virological synapses. This model was developed based on in vitro evidence in which infected cells establish cell-cell contact with uninfected cells. Applying intravital microscopy, we were recently able to provide in vivo support for the existence of virological synapses within the lymph node of living mice. Visualizing cells infected with fluorescently labeled murine leukemia virus (MLV) we identified B cells that were able to form long-lived virological synapses with uninfected lymphocytes [1]. In vivo virological synapses were, like their in vitro counterpart, dependent on the expression of the viral envelope glycoprotein (Env) and characterized by a prolonged polarization of viral capsid to the cell-cell interface. B cells were among the first cells to become infected by incoming MLV. However, the specific subtype of B cells that is susceptible to MLV had remained unknown.