Ths study will investigate the potential for sex differences to affect how HIV can be cured. Specifically, this team will examine the degree to which virus in women versus men is latent, and any differences in the mechanisms whereby that virus is maintained in a latent state. It has recently been demonstrated that the estrogen receptor, which is located on the nucleus, suppresses HIV transcription through a complex signaling pathway. Dr. Karn and colleagues will measure the size of the latent reservoir, its location within specific spans of DNA, and the ease with which it can be reactivated by biological as well as pharmacological tools. Since reactivation of latent virus is a key component to a leading strategy to cure HIV, it will be important to determine whether the sexes differ in their ability to respond to this treatment.