Selection of human anti-HIV broadly neutralizing antibodies occurs within the context of frozen 1F7-idiotypic repertoire

Objective: Most HIV-infected individuals develop HIV-specific antibodies (Abs) exhibiting a common idiotype designated as 1F7. Expression of this idiotype establishes idiotypic-driven repertoire freeze, maintaining antibody responses ineffective at controlling autologous contemporaneous viruses. As such, this study investigated the temporal dynamics of 1F7-idiotype expression, as well as the role of this idiotype in the selection of HIV-specific broadly neutralizing antibodies (BnAbs). Design: This study investigated the timing of appearance and persistence of 1F7-idiotypic HIV-specific Abs by screening plasma samples from individuals followed longitudinally starting in primary HIV infection. The expression of 1F7 on HIV-specific BnAbs was also investigated to determine whether their development occurs within the context of 1F7-idiotypic repertoire freeze. Methods: The 1F7 idiotype was detected on gp120, gp41 and membrane proximal external region (MPER) peptide-specific Abs using an enzyme-linked immunosorbent assay (ELISA). HIV-specific Abs in longitudinal plasma samples from six patients and six BnAbs were tested for the presence of the 1F7 idiotype. Results: The idiotype was expressed on HIV-specific Abs within 3 months of infection, with the magnitude of 1F7 detection increasing with time from infection. The 1F7 idiotype was also expressed on all BnAbs tested. Conclusion: These results demonstrate that HIV-specific antibody responses are restricted within the 1F7 idiotype from early infection onwards, and that six well characterized BnAbs developed within the context of 1F7-idiotypic repertoire freeze. Future research should evaluate the necessity of the 1F7 idiotype for broad neutralization, and determine if vaccines should target Abs within or outside this idiotypic space. (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins