 Part 1 aims to determine the origin of HIV infected naïve T-cells in vivo by assessing the viral relatedness between HIV strains from naïve and memory CD4 T-cells. To do this we will be studying ten chronically infected individuals. Naïve and memory CD4 T-cells from these individuals will be purified using a magnetic bead sorting MACS strategy. Envelope sequences will then be isolated and subjected to diversity calculation 