Figure 1.

Innate immune response against HPV. (a) The HPV viral particle infects the basal cells, gaining access through microtrauma. Several elements of the immune response are highly active throughout the different layers of the epithelium including APC, NK and NKT, which are responsible for recognizing and clearing infectious agents. (b) Infected cells are recognized by NK cells through KIR receptors, inducing their elimination by releasing their cytoplasmic granules containing granzyme, perforin and cytokines. Moreover, NKT cells control infection by other mechanisms. For example, the CD1d receptor activates NKT cells to produce apoptosis of the infected cell and cytokine release that will help activate the adaptive immune response. NKT cells act as a bridge between innate and adaptive immunity. (c) Once the cell is infected by HPV, the TLR-9 receptor detects the viral genome in the cytoplasm. Then, TLR-9 activates IFN-I production and ISG expression promoting an antiviral effect. Figure created using BioRENDER.com.