T cells are the main target of HIV in the blood, and they act as the host that the virus needs in order to replicate. (However, macrophages, B cells, monocytes, and other cells in the body can also be infected by HIV.) The T cell has a nucleus that contains genetic material in the form of DNA (deoxyribonucleic acid) (Figure 2). The cell's DNA has all the information that the cell needs in order to function.