The purpose of this study is to determine whether the adjunctional of interferon alfa to structured treatment interruptions correlated with a long time off treatment in HIV-1 infection.

The limitations of the drugs used against HIV include their toxicity, their tolerability, their propensity to induce resistance when not taken with absolute regularity and their cost. Treatment interruption in patients receiving antiretroviral treatment in the setting of chronic infection is associated with viral rebound and rapid CD4 T cell decrease conducting to antiretroviral therapy restart. In patients with high CD4+ cell counts (patients receiving treatment of chronic infection with controlled viremia and patients who are receiving highly active antiretroviral therapy (HAART) now in whom treatment would not have been started based on current guidelines), the investigators evaluated whether the adjunctional of interferon alfa 2b to 3 structured treatment interruptions correlated with a long time off treatment. HAART was interrupted for 4 weeks, restarted and continued for 12 weeks. After 3 such cycles treatment was indefinitely suspended 48 weeks after study entry. Another aim of this study was to assess the immunological and virological factors associated with the duration of treatment interruption (proviral HIV DNA at baseline and during follow-up, plasma HIV RNA at baseline and during follow-up, CD4 T cell and CD8 T cell HIV specific responses at baseline and after 6 months of interruption).

Inclusion Criteria:

• Males and non pregnant females
• Confirmed laboratory diagnosis of HIV infection
• Have been on the same continuous HAART regimen for at least 6 months prior to inclusion
• Viral load below 50 cp/ml for at least 6 months
• CD4 over 350 cells/mm3
• Previous viral load over 10000 cp/ml in their history
• No CD4 cell count under 100/mm3 in their history
• For women of reproductive ages: negative serum pregnancy test
• Signed written consent to participate.

Exclusion Criteria:

• Already had interferon or interleukin-2 (IL-2)
• Positive hepatitis C virus (HCV) PCR
• Under treatment with abacavir during screening
• Serious psychiatric history, suicide attempt, or severe depression
• History of thyroid abnormality
• Opportunistic infection ongoing
• Lymphoma or Kaposi's sarcoma (KS) under chemotherapy