To characterize a purified panel of monoclonal antibodies (MAb) to epitopes in HIV-1 envelope V3, CD4-binding region, C4 and 8p41.Design
Neutralization and/or binding activity data were obtained from 21 laboratories on a coded panel consisting of seven human MAb, seven mouse MAb, recombinant human CD4 immunoadhesin [CD4-immunoglobulin G (IgG)], normal human and normal murine lg.Methods
Laboratories performed a variety of neutralization assays and antigen binding assays with HIVIIIB, HIVMN and other laboratory strains of HIV-1.Results
For a single MAb, there was up to a 103 range of neutralizing antibody titers between laboratories. The range in titers appeared to depend on the sensitivity of the neutralization assay. Two methods were used to consolidate the data from all laboratories, the geometric mean titer (GMT) and the median neutralizing titer (MNT). The panel of MAb were also analyzed by a variety of assays that measure binding activity to native or denatured epitopes. The relative binding activity of the MAb did not appear to correlate with neutralizing activity.Conclusion
Neutralization results from any single laboratory did not correlate with the collective data. The relative potency (rank order) of the MAb in the panel were equivalent when determined by GMT or MNT. These values may be useful to individual laboratories for estimating the sensitivity of their neutralization assays. The study also identified potential reference reagents with which neutralizing activity could be compared.