<qa>  What is the effect of three different antiretroviral regimens on endotheliEndothelial dysfunction, assessed by measurement of brachial artery reactivity, is associated with coronary artery disease. Previous studies showed that patients taking HIV protease inhibitors PIs had a buildup of fatty deposits in their arteries and impaired flow-mediated vasodilation of the brachial artery, whereas endothelial function was normal in HIV-infected individuals not taking PIs. The effect of three different antiretroviral regimens on endothelial function in antiretroviral naïve HIV-infected patients will be examined in this substudy. 