Structural and immunogenetic determinants of antibody recognition of viral glycoproteins in vaccination and natural infection

Abstract

Antibody responses against enveloped viruses require recognition of structurally complex and variably shielded surface glycoproteins, posing major challenges for vaccine design. This dissertation integrates structural, functional, and immunogenetic analyses of antibody recognition of the surface glycoproteins of orthomarburgviruses and human immunodeficiency virus type 1 (HIV-1) to define conserved structural vulnerabilities. High-resolution structural analyses provide the first characterization of a previously structurally undefined protective epitope on the orthomarburgvirus glycoprotein (GP), termed the GP2 wing, and reveal convergent recognition across four independent antibody lineages. Immunogenetic analyses identify shared sequence features across antibodies from different species, highlighting reproducible germline-encoded solutions that establish the GP2 wing as a structurally conserved site of immune vulnerability capable of supporting broad cross-orthomarburgvirus recognition. To investigate orthomarburgvirus GP conformational dynamics in a more native context, antibody binding to full-length cell-surface expressed GP was examined across a temperature gradient, revealing that accessibility to the receptor-binding region (RBR) is temperature-dependent and influenced by the mucin-like domain (MLD), whereas recognition of the GP2 wing region remains unchanged. These findings provide evidence for temperature-dependent conformational sampling of the RBR epitope and support the GP2 wing as a functionally accessible protective epitope. Extending these principles beyond filoviruses, structural analyses of liposome-based vaccine-elicited antibodies in humans targeting the HIV-1 envelope membrane-proximal external region (MPER) reveal convergent recognition of a highly conserved helical epitope by a newly discovered immunogenetic class of antibodies. Together, these findings define genetic, structural, and functional determinants of antibody recognition of conserved viral epitopes and provide a framework for rational vaccine immunogen design against these lethal human viral pathogens.