The objective of the study is to identify the pathophysiological mechanisms responsible for the induction and maintenance of negative serologies by EIA tests in HIV-infected children treated early with HAART in the ANRS 12225-Pediacam III cohort in Cameroon

The hypothesis of better control of HIV infection through interactions between immunological, viral, and genetic factors was made to build the following objectives:

• Immunological aspect: lack of humoral response or immune activation
• Virological aspect: Reduced HIV reservoir size
• Determine the HLA phenotype in the different groups of children included and the KIR genotypes.

There will be two phases of the study :

• A retrospective phase: case-control study The analyzed data are those collected previously or measured from the already available bio bank, within the framework of the Pediacam III cohort during the primary infection phase before the initiation of HAART, at 6 months after the end of the first series of EPI vaccines, and at 2 years.
• A prospective phase: cross-sectional study Based on an ad hoc bio bank created for parameters we couldn't measure on the existing bio bank

Inclusion Criteria:

Case control study

• Children included and followed in the ANRS 12225 study - Pediacam III
• Having plasma samples in the bio bank during the above-mentioned periods Case:children with at least one negative HIV serology made by ELISA, permanent or transientduring follow-up.

Control (4 groups)

• HIV-infected children with positive serology and viral load (VL) <400 copies /ml
• HIV-infected children with positive serology and VL ≥400 copies / ml
• HIV-uninfected children born to HIV-positive mothers
• HIV-uninfected children born to HIV-uninfected mothers Selection of cases and controls will be matched on gestational age (premature <37, term ≥37 weeks) and year of birth (2007-2008 and 2009-2010).

Cross sectional study Inclusion criteria

• All children still followed in the ANRS - Pediacam III cohort
• Written consent of one of the parents or the guardian and assent of the child if aged ≥ 11 years and complete disclosure of HIV statusfor infected children for participation to the study.

Exclusion Criteria:

• Refusal by one of the parents or the guardian for the child's participation in the study
• No assent of the child (if aged ≥ 11 years and with complete disclosure of HIV status, for infected children)