Fig. 1.

The dynamics of MV clearance. MV infection results in transient viremia (purple line, Lower) that is cleared within ∼2 wk, coincident with CD8⁺ T-cell responses. MV RNA (red line, Lower) persists, however, for as long as months in blood. In the acute phase of infection, most MV is likely produced by infected lymphocytes. The source of persistent MV RNA is unknown, but could come from infected lymphocytes, follicular dendritic cells, or possibly other cell types, including epithelial cells in lung, liver, or kidney. Lin et al.’s modeling studies (9) point to an important role for Abs in clearing persistently infected cells that are the source of MV RNA.