Priscila M. S. Castanha; Patrick J. McEnaney; Yongseok Park; Anthea Bouwer; Elton J. F. Chaves; Roberto D. Lins; Nicholas G. Paciaroni; Paige Dickson; Graham Carlson; Marli T. Cordeiro; Tereza Magalhaes; Jodi Craigo; Ernesto T. A. Marques; Thomas Kodadek; Donald S. Burke Proc. Natl. Acad. Sci. USA, 2024, 121(21), e2312755121 https://doi.org/10.1073/pnas.2312755121
Abstract
Significance Zika virus (ZIKV) remains a global health threat of high priority. ZIKV is closely related to the dengue viruses, and its spread in dengue-endemic areas poses significant challenges to the development of virus-specific diagnostic tools and effective vaccines. We screened combinatorial libraries of small synthetic molecules to efficiently identify a nonbiological molecule “CZV1-1” that binds specifically to IgG present in serum from Zika-immune persons, but not in serum from dengue-immune persons. CZV1-1 mimics a major Zika-neutralizing envelope epitope and can serve as a biomarker for evidence of prior Zika infection in flavivirus-endemic areas. This approach can be used to find small-molecule mimics of important epitopes for a wide range of other infectious and noninfectious diseases. Abstract 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 fluorescence-activated cell sorter-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 (mAbs) 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-neutralizing mAbs. This study demonstrates an innovative approach for identification of synthetic non-natural molecular mimics of conformational virus epitopes. Such molecular mimics may have value in the development of accurate diagnostic assays for Zika, as well as for other viruses.