Fig. 1.

Neutralization screening of primary IgG⁺ memory B cell cultures. IgG⁺ memory B cells were isolated from the peripheral blood of a broad neutralizer African subject chronically infected with a clade A HIV-1 strain. IgG⁺ memory B cells were cultured at a density of 8 cells/well in 3,600 culture wells for 14 days as described in Materials and Methods. At the end of stimulation, crude supernatants were tested for neutralizing activity against reporter tier 2 HIV-1 clade C isolate CAP45, a difficult-to-neutralize virus that was effectively neutralized by this subject's serum (Tomaras et al., unpublished). Solid dots represent the percentage of neutralization of each of the 3,600 cultures. Monoclonal antibodies CH01 to CH04 were isolated from the cultures represented by circled red dots. Positive controls (HIV Ig) are shown as open circles on the far right.