Figure 2.

Mechanisms involved upon HPV infection. Upon HPV infection, the host immune system triggers the toll-like receptors (TLR) to activate the nuclear factor-kappa B (NF-κB) and interferon regulatory factor 3 (IRF3) to activate pro-inflammatory factors and antiviral cytokines. The TLR also activate the major histocompatibility complex (MHC) class I and II. However, the HPV can express its viral oncoprotein E5 to inhibit the MHC class I mechanisms. The oncoprotein E6 has the ability to inhibit the production of IRF3. The oncoprotein E6 also binds to Yes-associated protein (YAP1), preventing degradation of YAP1, and inhibiting the TLR.