This application proposes a supplement to the University of Colorado Center for AIDS Research (UC-CFAR) to address two important and under-studied areas of AIDS research: [unreadable] * The role of sex and gender, and age in HIV treatment, and [unreadable] * The implications of co-infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) in HIV pathogenesis and therapeutic studies [unreadable] The specific aims of this application are: (1) To build collaborative research capacity by integrating antiretroviral clinical pharmacology resources and expertise with the activities of the UC-CFAR clinical, laboratory, and developmental cores; and (2) To initiate program development and generate preliminary data by prospectively evaluating clinical pharmacologic characteristics of antiretrovirals in a longitudinal cohort of HIV-infected girls, women, and patients with HBV or HCV co-infection. The investigators in this proposal have established expertise in the AIDS research areas listed above, and [unreadable] have a demonstrated track record for establishing collaborations with investigators in other disciplines. The work proposed in this supplement provides an opportunity to integrate resources and expertise in antiretroviral clinical pharmacology, which complements existing research being undertaken by the UC-CFAR, and to build new collaborative research programs that presently do not exist at the UC-CFAR with the clear potential to maintain the program through more traditional sources of funding after completion of the supplement. Funding of this supplement would facilitate the discovery and application of new knowledge that can be directly translated into the management of the HIV infected individual to increase the likelihood of therapeutic success with HIV and HCV/HBV treatments and minimize the risk of adverse effects. [unreadable] [unreadable]