It has been proposed that the γ-herpesviruses maintain lifelong latency in B cells by gaining entry into the memory B cell pool and taking advantage of host mechanisms for maintaining these cells. We directly tested this hypothesis by kinetically monitoring viral latency in CD40+ and CD40- B cells from CD40+CD40- mixed bone marrow chimera mice after infection with a murine γ-herpesvirus, MHV-68. CD40+ B cells selectively entered germinal centers and differentiated into memory B cells. Importantly, latency was progressively lost in the CD40- B cells and preferentially maintained in the long-lived, isotype-switched CD40+ B cells. These data directly demonstrate viral exploitation of the normal B cell differentiation pathway to maintain latency.