Cedar virus (CedV) is a bat-borne henipavirus related to Nipah virus (NiV) and Hendra virus (HeV), zoonotic agents of fatal human disease. CedV receptor-binding protein (G) shares only ∼30% sequence identity with those of NiV and HeV, although they can all use ephrin-B2 as an entry receptor. We demonstrate that CedV also enters cells through additional B- and A-class ephrins (ephrin-B1, ephrin-A2, and ephrin-A5) and report the crystal structure of the CedV G ectodomain alone and in complex with ephrin-B1 or ephrin-B2. The CedV G receptor-binding site is structurally distinct from other henipaviruses, underlying its capability to accommodate additional ephrin receptors. We also show that CedV can enter cells through mouse ephrin-A1 but not human ephrin-A1, which differ by 1 residue in the key contact region. This is evidence of species specific ephrin receptor usage by a henipavirus, and implicates additional ephrin receptors in potential zoonotic transmission.

Hendra Virus in Horse in Australia

Significance: A new Hendra virus variant (HeV-g2) has been recently identified in two independent studies, increasing the concern of HeV spillover. Here, we show that HeV-g2 utilizes the same host receptor as HeV and that a panel of previously described HeV neutralizing antibodies cross-neutralizes HeV-g2 potently. Furthermore, we describe a monoclonal antibody (hAH1.3) neutralizing HeV and HeV-g2 and reveal its epitope using X-ray crystallography. We show that targeting four nonoverlapping epitopes on the HeV attachment protein simultaneously leads to potent HeV and HeV-g2 neutralization, supporting the development of a tetravalent monoclonal antibody cocktail. Collectively, our data provide a comprehensive assessment of available countermeasures against this newly described HeV-g2 variant and delineate multiple strategies for pandemic preparedness.

Significance: Many current vaccines seek to elicit protective antibody responses along precise evolutionary pathways, and a fundamental understanding of genetic, structural, and biophysical antibody development features will accelerate guided vaccine strategies. Here we determine the structural and biophysical features associated with improvement or fitness of an antibody targeting the HIV fusion peptide, a known vulnerable site on HIV-1. We show that around 1% of possible antibody mutations can improve virus recognition. Beneficial mutations were often clustered far from the binding interface and altered protein structure and dynamics, leading to reduced antibody thermal stability and higher binding affinity to the HIV envelope trimer. These data quantify the genetic and biophysical landscape for improvement of a vaccine-elicted antibody and provide a rational framework to guide HIV vaccines.

Broadly neutralizing antibodies (bnAbs) isolated from HIV-infected individuals delineate vulnerable sites on the HIV envelope glycoprotein that are potential vaccine targets. A linear epitope within the N-terminal region of the HIV-1 fusion peptide (FP8) is the primary target of VRC34.01, a bnAb that neutralizes ~50% of primary HIV isolates. FP8 has attracted attention as a potential HIV vaccine target because it is a simple linear epitope. Here, platform technologies based on RNA bacteriophage virus-like particles (VLPs) were used to develop multivalent vaccines targeting the FP8 epitope. Both recombinant MS2 VLPs displaying the FP8 peptide and Qβ VLPs displaying chemically conjugated FP8 peptide induced high titers of FP8-specific antibodies in mice. Moreover, a heterologous prime-boost-boost regimen employing the two FP8-VLP vaccines and native envelope trimer was the most effective approach for eliciting HIV-1 neutralizing antibodies. Given the potent immunogenicity of VLP-based vaccines, this vaccination strategy—inspired by bnAb-guided epitope mapping, VLP bioengineering, and prime-boost immunization approaches—may be a useful strategy for eliciting bnAb responses against HIV.

• A novel anti-ADAM17 monoclonal antibody, D8P1C1, has been developed. • D8P1C1 inhibits the proteolysis of peptide substrates by ADAM17. • D8P1C1 inhibits the proliferation of cancer cells and tumor growth inhibition in vivo. • D8P1C1 preferentially recognizes ADAM17 on cancer cells. • Negative stain EM analysis reveals that D8P1C1 binds to the ADAM17 protease domain.