TAT and HIV infectious disease: The accessory proteins Tat, Nef and RT - which contain several prominent human cytotoxic T-lymphocyte (CTL) epitopes - are of particular interest in HIV vaccines: responses to Tat and Nef correlate with non-progression of HIV infections and possible protection [9], while RT-specific CTLs induce potent Th1 responses in mice, when administered in low doses [13].