Neutralization mechanism of a highly potent antibody against Zika virus

Abstract

The rapid spread of Zika virus (ZIKV), which causes microcephaly and Guillain-Barré syndrome, signals an urgency to identify therapeutics. Recent efforts to rescreen dengue virus human antibodies for ZIKV cross-neutralization activity showed antibody C10 as one of the most potent. To investigate the ability of the antibody to block fusion, we determined the cryoEM structures of the C10-ZIKV complex at pH levels mimicking the extracellular (pH8.0), early (pH6.5) and late endosomal (pH5.0) environments. The 4.0 Å resolution pH8.0 complex structure shows that the antibody binds to E proteins residues at the intra-dimer interface, and the virus quaternary structure-dependent inter-dimer and inter-raft interfaces. At pH6.5, antibody C10 locks all virus surface E proteins, and at pH5.0, it locks the E protein raft structure, suggesting that it prevents the structural rearrangement of the E proteins during the fusion event—a vital step for infection. This suggests antibody C10 could be a good therapeutic candidate.

Monoclonal Antibodies against Zika Virus: Therapeutics and Their Implications for Vaccine Design

“…Thus, E dimers are locked by MAb C10, which inhibits domain reorganization. Consistently, the E protein layer of the ZIKV-C10 complex at pH 6.5 remains at a radius similar to that seen with the uncomplexed ZIKV at pH 8.0, unlike uncomplexed ZIKV at pH 6.5 (19). Similar intradimer epitopes are also observed for MAb C8 and MAb A11 (11) (Fig.…”

“…Structural studies have shed light on the neutralizing mechanisms of MAbs. Taking MAb C10 as an example (19), this MAb covers the region of FL on DII of one protomer of the virion and makes contact with DIII, DI, and DII on the other protomer (Fig. 1B).…”

Rational Engineering and Characterization of an mAb that Neutralizes Zika Virus by Targeting a Mutationally Constrained Quaternary Epitope

“…It must be noted that conventional epitope scanning methods using sequence-based approaches or analysis of a single domain or E-protein dimer did not lead to the selection of the FLEP epitope. As mentioned earlier, there was limited structural information available at the start of this work, and as a consequence we had to develop a homology model of the E-protein ZIKV assembly, which is validated by several recent structural studies (Kostyuchenko et al, 2016; Sirohi et al, 2016; Zhang et al, 2016b). This is significant because it was important to capture geometrical parameters when identifying potential quaternary epitopes that span or fall near E-protein dimer interfaces, as these are enormously influenced by the membrane curvature and inter-chain interface orientations about symmetry axes of the assembly.…”

“…To prepare ZIKV-Fab complexes for CryoEM, Fab and ZIKV virions were mixed with a E protein: Fab (ZAb_FLEP) molar ratio of 1:2 as described to ensure full occupancy (Zhang et al, 2016a). The immune complex was allowed to form by incubation at 37°C for 30 min.…”

Zika Virus Pathogenesis and Tissue Tropism

“…Highly neutralizing mouse and human anti-ZIKV monoclonal antibodies bind to distinct epitopes in the E protein including the lateral ridge of domain III ( e.g ., ZV-67) (Zhao et al, 2016), a domain I–III interface epitope ( e.g ., Z23) (Wang et al, 2016), an EDE intra-dimer epitope ( e.g ., C10) (Zhang et al, 2016), domain I–II and domain II intra-dimer epitopes ( e.g ., Z3L1 and Z20, respectively) (Wang et al, 2016), and a domain II inter-dimer epitope (e.g ., ZIKV-117) (Sapparapu et al, 2016). These epitopes represent candidate regions for ZIKV vaccine design.…”