Identification and characterization of a non-biological small molecular mimic of a Zika virus conformational neutralizing epitope
Antigenic similarities between Zika virus (ZIKV) and other flaviviruses pose challenges to the development of virus-specific diagnostic tools and effective vaccines. Starting with a DNA-encoded one-bead-one-compound combinatorial library of 508,032 synthetic, non-natural oligomers, we selected and characterized small molecules that mimic ZIKV epitopes. High-throughput FACS_x0002_based bead screening was used to select molecules that bound IgG from ZIKV-immune but not from dengue-immune sera. Deep sequencing of the DNA from the “Zika-only” beads identified 40 candidate molecular structures. A lead candidate small molecule “CZV1-1” was selected that correctly identifies serum specimens from Zika-experienced patients with good sensitivity and specificity (85.3% and 98.4%, respectively). Binding competition studies of purified anti-CZV1-1 IgG against known ZIKV-specific monoclonal antibodies showed that CZV1-1 mimics a nonlinear, neutralizing conformational epitope in the domain III of the ZIKV envelope. Purified anti-CZV1-1 IgG neutralized infection of ZIKV in cell cultures with potencies comparable to highly specific ZIKV_x0002_neutralizing monoclonal antibodies. This study demonstrates an innovative approach for discovery of synthetic non-natural molecular mimics of conformational virus epitopes. Such molecular mimics may have value in the development of novel diagnostic assays and vaccines for Zika, as well as for other viruses. Overall design: Sera were collected from persons who had experienced prior dengue infections only, prior Zika infection only, or neither infection. Sera of individuals without previous serological markers of Zika and dengue infections are used as negative controls to identify PICCOs binding to Zika or dengue infected sera.” A DNA encoded library of One Bead One Compound beads was synthesized that expressed a combinatorial library of 500,000 + "random" PICCOs Peptoid Inspired Conformationally Constrained Oligomers. The DNA encoded the ordering of the oligomers in the PICCO, as well as a bead specific barcode PICCO-Beads were mixed with pools of human sera with known zika or dengue infection history, and binding was assessed by flow cytometry sorting to select beads with bound antibody The DNA on beads with a high number of flow cytometry Zika hits, high dengue hits, or both, were subjected to NGS Based on the DNA sequences, the chemical structures of PICCOs were identified Based on their chemical structures, high hit PICCOs were clustered into groups with similar chemical structures High interest PICCOs that bound exclusively Zika, or dengue, or both, were resynthesized on beads High ingterest PICCO-beads were evaluated for their sensitivty and specificity in diagnosing Zika