CD4 and infection: Throughout the papillomatous tissues taken after 7 weeks of depletion (corresponding to 6 weeks post-infection) from the CD3-depleted mice (Figure 3J and 3K; representative of group day −7 shown), exceptionally large amounts of MusPV1 L1 protein were detected by IFS, and CD4+ (Figure 3J) and CD8+ (Figure 3K) T cells were absent, as expected, since these T cells are CD3+.