Trafficking of immune cells into and out of lymph nodes is essential for immune surveillance of foreign invaders. CD4 T cells have a preference to home to germinal centers once they are activated  and follicular helper T cells only circulate amongst the lymph follicles . As immune privileged sites for the activation and selection of B cell responses, the germinal center is outside the scope of cytotoxic CD8 T cells  or natural killer cells. Accordingly, germinal centers are plausible foci for persistent viral replication  and offer particular challenges in regards to the use of trafficking therapy.