Antigenic mapping and functional characterization of human New World hantavirus neutralizing antibodies

Abstract

Hantaviruses are high-priority emerging pathogens carried by rodents and transmitted to humans by aerosolized excreta or, in rare cases, person-to-person contact. While infections in humans are relatively rare, mortality rates range from 1 to 40% depending on the hantavirus species. There are currently no FDA-approved vaccines or therapeutics for hantaviruses, and the only treatment for infection is supportive care for respiratory or kidney failure. Additionally, the human humoral immune response to hantavirus infection is incompletely understood, especially the location of major antigenic sites on the viral glycoproteins and conserved neutralizing epitopes. Here, we report antigenic mapping and functional characterization for four neutralizing hantavirus antibodies. The broadly neutralizing antibody SNV-53 targets an interface between Gn/Gc, neutralizes through fusion inhibition and cross-protects against the Old World hantavirus species Hantaan virus when administered pre- or post-exposure. Another broad antibody, SNV-24, also neutralizes through fusion inhibition but targets domain I of Gc and demonstrates weak neutralizing activity to authentic hantaviruses. ANDV-specific, neutralizing antibodies (ANDV-5 and ANDV-34) neutralize through attachment blocking and protect against hantavirus cardiopulmonary syndrome (HCPS) in animals but target two different antigenic faces on the head domain of Gn. Determining the antigenic sites for neutralizing antibodies will contribute to further therapeutic development for hantavirus-related diseases and inform the design of new broadly protective hantavirus vaccines.

Validation of an antigenic site targeted by monoclonal antibodies against Puumala virus

“…Our literature search identified 24 amino acid changes in the Gc that convey neutralization escape from antibodies against PUUV, Hantaan virus (HTNV), Andes virus (ANDV), and Sin Nombre virus (SNV) (Table S1, available in the online version of this article). We note that 21 of the 24 sites were reported in 2020 or later [15–17], allowing us to perform the most comprehensive mapping of Gc neutralization escape mutation sites to date.…”

“…Beyond the insights gained from the spatial distribution of NE sites, we note that specific regions within the Gc may be under strict functional constraints that could limit the occurrence of NE mutations, despite the importance of these regions for antibody-mediated neutralization. Recent evidence has shown that the apex of Gc domain II, containing the hantaviral fusion loops, and targeted by ADI-42898 () [14], ADI-37236 and ADI-42089 [16], and SNV-53 [15], presents such a site. Taken together, the picture emerging from recent structural and functional findings highlights at least two prominent regions of vulnerability in hantaviral Gc: the region of the 4G2 epitope that lies at the junction of domains I and II (possibly extending to the top of domain I), and the tip of Gc domain II that houses the fusion loops, shielded by Gn.…”

“…Recent evidence has shown that the apex of Gc domain II, containing the hantaviral fusion loops, and targeted by ADI-42898 (Fig. 4) [14], ADI-37236 and ADI-42089 [16], and SNV-53 [15], presents such a site. Taken together, the picture emerging from recent structural and functional findings highlights at least two prominent regions of vulnerability in hantaviral Gc: the region of the 4G2 epitope that lies at the junction of domains I and II (possibly extending to the top of domain I), and the tip of Gc domain II that houses the fusion loops, shielded by Gn.…”

“…To understand whether this region, implicated in antibody recognition for both bank vole and human anti-PUUV mAbs, is widely targeted across hantaviruses, we mapped all known neutralization escape (NE) sites discovered in hantaviral Gc proteins onto the Gc protein of PUUV. While only two crystal structures of neutralizing antibodies in complex with hantaviral Gc have been published to date (PDB 6Z06 released in 2020 [8], and PDB 7QQB released in 2023 [14]), recent studies have greatly expanded the portfolio of neutralizing antibodies targeted against hantaviral Gn and Gc proteins and their associated neutralization escape sites [15][16][17]. Our literature search identified 24 amino acid changes in the Gc that convey neutralization escape from antibodies against PUUV, Hantaan virus (HTNV), Andes virus (ANDV), and Sin Nombre virus (SNV) (Table S1, available in the online Fig.…”

“…version of this article). We note 21 of the 24 sites were reported in 2020 or later [15][16][17], allowing us to perform the most comprehensive mapping of Gc neutralization escape mutation sites to date.…”