HIV is a virus that can lead to acquired immunodeficiency syndrome (AIDS), a disease for which there is not yet a cure. Antiretroviral therapy (ART) has proven an effective treatment for inhibiting the replication of HIV, allowing for improved quality of life and survival. Previous studies indicate that episodic use of ART is associated with increased risk of cardiovascular disease (CVD). This study will determine mechanisms underlying the increased CVD risk among people infected with HIV and, specifically, in those who receive episodic ART.