A High-Affinity and Potently Neutralized Nanobody against Zika Virus

ZIKA virus (ZIKV), an emerging pathogen for which no licensed drugs or vaccines exist, has attracted global attention. ZIKV envelope protein domainIII (EDIII) can induce neutralizing antibodies with minor cross-reactive epitopes among flaviviruses. Currently, no nanobodies against the ZIKV EDIII protein are available. In our study, 15 nanobodies were derived from a naive phage library. High-affinity and specific nanobodies of Nb-C9, Nb-D8, Nb-E3, and Nb-E5 were selected in <i>vitro</i> showing dissociation constants of 8.24, 6.59, 2.52, and 8.22 nM, respectively. The Nb-E3 and Nb-E5 potently neutralized strain ZIKV-GD01 with plaque reduction neutralization test (PRNT)50 values of 0.1875 and 0.0234 μg/mL, respectively. In addition, a linear epitope Z17-VGEKKITHHWHRS recognized by Nb-E5 showed potential as a candidate for the development of epitope-based vaccines. These findings may contribute to the development of a new therapeutic strategy against ZIKV infection.