In 2009, Yu et al. showed that the microRNAs, including miR-17–92 involved in CXCR5 repression, are repressed by BCL-6-driving cells toward Tfh differentiation (101), while during viral infection, over-expression of miR-17–92 is importantly involved in Tfh differentiation (138, 139). Here, BCL6 is linked to viral infectious disease.