TAT and HIV-1 infection: Thus, HIV-1 Tat may be involved in pain at all stages of HIV-1 infection, i.e. the rapid onset of DRG hyperexcitability triggered by Tat may be mainly responsible to pain at very early stages of HIV-1 infection, whereas Tat-mediated chronic apoptosis of sensory neurons causes and accelerates pain in the advanced stages of the disease.