HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 NEUTRALIZING ANTIBODY SEROTYPING USING SERUM POOLS AND AN INFECTIVITY REDUCTION ASSAY

Classification of human immunodeficiency virus type 1 (HIV-1) by neutr alization serotype may be important for the design of active and passi ve immunization strategies. Neutralizing antibody serotyping is hinder ed by the lack of standard reagents and assay format, and by the weak activity of many individual sera. To facilitate cross-clade neutraliza tion analysis, we used an infectivity reduction assay (IRA) and select ed clade-specific serum (or plasma) pools from subjects infected with clade B and E HIV-1, respectively, Several serum pools were utilized; some were selected for strong neutralizing activity against intraclade viruses and others were derived from conveniently available samples, Against a panel of 51 clade B and E viruses, serum pools displayed str ong neutralization of most intraclade viruses and significantly dimini shed cross-clade neutralization, Results mere confirmed against a blin ded panel of 20 viruses, The data indicate that the phylogenetic class ification of virus subtypes B and E corresponds to two distinct neutra lization serotypes, This approach to neutralizing antibody serotyping may be useful in defining the antigenic relationship among viruses fro m other clades.