Inclusion Criteria:

For all patients:

• HIV-infected patient
• Age greater 18 years
• No acute AIDS-defining disease or history of AIDS- defining disease
• CD4-cell nadir above or equal 200 cells/microliter
• Hemoglobin greater 8 g/dl
• Neutrophil count greater 750 cells/microliter
• Platelet count greater 50.000 cells/microliter
• AST/ALT below 5x upper limit of normal range
• No evidence for drug intolerability
• No prior use of an HIV integrase inhibitor or CCR5 antagonist
• No presence of malignancy (requiring active treatment and malignancy within 5 years prior to enrolment (even if in complete remission)
• No significant underlying disease (non-HIV) that might impinge upon disease progression or death
• No history of alcohol or other substance abuse or other condition which in the opinion of the investigator would interfere with the patient compliance or safety.
• Written informed consent
• For males and premenopausal females use of acceptable methods of birth control during the entire study and for 6 weeks thereafter
• No pregnancy (for premenopausal women: negative serum or urine pregnancy test within 48 hours prior to initiating study medications)
• No breastfeeding

For chronically HIV-infected patients:

• Continuous plasma viral load below 50 copies/ml for the preceding 36 months under HAART (two or less single viral load blips up to 500 copies/ml are allowed)
• Stable HAART (for at least 3 months) prior to the Screening visit consisting of 2 NRTI + 1 PI
• No history of virological failure
• No documented resistance to PI and NRTI
• CCR5-tropic virus

For patients with primary HIV infection:

• Detectable plasma viral load
• ELISA positive or negative and Western Blot negative or positive with less or equal 2 bands at screening visit
• No primary resistance to PI´s and NRTI´s
• CCR5-tropic virus