Inclusion Criteria:  Age 18 years or older. Confirmed HIV-1 or HIV-2 infection.  Exclusion Criteria:  Inability to place 2.5 cm venous catheter or perform phlebotomy  Major comorbidities:  A. Severe symptomatic anemia B. Recent symptomatic cardiovascular event (unstable angina pectoris, decompensated heart failure, myocardial infarction).  The inability to participate due to any other relevant medical, social, environmental, psychological, factors or according to the HIV treating physician's judgement