Modulation of HIV-1 transcription by cytokines and chemokines

Infection with HIV results in the modulation of circulating levels of many host factors. Several host proteins that are up-regulated in HIV infection have the potential to influence virus replication. More specifically, the transcription of HIV-1 can be modulated in vivo by host proteins, including cytokines and chemokines. Cytokines modulate transcription mediated by the HIV-1 long terminal repeat (LTR) via multiple signal transduction pathways with resulting recruitment of numerous transcription factors, including NFkappaB, C/EBP, AP-1, TCF-1alpha, NF-IL-6 and ISGF-3. The effects on transcription may vary depending upon the cell type studied and upon the timing of the exposure of infected or transfected cells to cytokines. Furthermore, studies of cytokine mediated activation or inhibition of LTR mediated transcription may also be affected by the presence of the HIV-1 trans-activating protein, Tat, which has significant impact upon the redox state of the cell. This review will examine the complexities of the positive and negative control of HIV transcription by cytokines and chemokines.