Principles in PRR signalling and transcription of cellular genes and HIV provirus. Sensing of microbial PAMPs by PRRs stimulates intracellular signalling pathways, leading to activation of transcription factors, notably NF-κB, IRF-1, and AP-1. These transcription factors bind to specific sequences present in gene promoter regions and activate transcription of antiviral and inflammatory genes. Importantly, NF-κB and AP-1 also activate transcription of the HIV provirus through binding to the corresponding elements in the HIV LTR to induce viral replication. TBK, TANK-binding kinase. IKK, IκB kinase.