The ANRS CO18 HIV Controller cohort set up in 2009 is stemming from the French National Observatory of HIV Controllers which was active between 2006 and 2008 (Study ANRS EP36). 152 patients are enrolled who are defined on virological criteria: the last 5 plasmatic viral loads should be below 400 copies/mL without any antiretroviral treatment, in HIV-infected patients for more than 5 years. A consortium of research teams has studied these patients and has shown that Controllers are infected with replication-competent HIV, that HIV infects CD4 T cells but that the viral replication in CD4 T cells is fully controlled by CD8 T cells.