The range of HIV-1 isolates neutralized by both the plasma and mAbs is greatest in the extended incubation 24/1/14 PBMC assay while only three of the 36 mAb/isolate combinations show significant neutralizing activity in the extended absorption 1/24/14 PBMC assay. The HJ16 mAb neutralizes three (SF162, VI 1888 and VI 1090) of the six isolates (92RW009, 93Br025 and CA18) neutralized by the plasma in 1/2/7 PBMC assays (table 5). The HGN194 mAb neutralizes SF162, VI 1888 and 92RW009 while the corresponding plasma do not produce significant neutralization against any isolate in these assays. The HK20 mAb only neutralizes VI 1888. When the absorption and culture phases of the assay are extended to the 1/24/14 setup, HJ16 still neutralizes VI 1090, HGN194 neutralizes SF162 and VI 1888 while HK20 neutralizes VI 1090 for 80%.