While protective immunity after wsp immunization is thought to largely dependent on the killing infected hepatocytes by CD8+ T cells and IFN-γ (Tarun et al., 2007; Douradinha and Doolan, 2011; Khan et al., 2012), adoptive transfer of CD4+ T cells from GAP-immunized C57BL/6 mice was able to provide sterile protection to 50% of naïve animals against a WT infection, indicating an important role for CD4+ T cells in GAP induced immunity (Tarun et al., 2007). Here, CD4 is linked to infection.