Eligible patients visiting the ITM clinic in Antwerp had been infected for at least one year, were clinically asymptomatic and over 18 years old. Neither CD4 T cell counts nor viral loads were taken into consideration. Patients were preferentially selected from sub-Saharan regions where the subtypes A, C and/or CRF02_AG are prevalent. Plasma was subsequently screened for its ability to neutralize a panel of four subtype A, four subtype C and six CRF02_AG primary HIV-1 strains, in our extended incubation phase PBMC assay (see below).