PhD student Daman Yadav successfully defends dissertation

June 9, 2026 — University of Minnesota Biomedical Engineering PhD student Daman Yadav successfully defended his dissertation, "Identifying Cellular and Molecular Mechanisms of Amphiphile Protein Subunit Vaccines that Drive B Cell Activation and Immunity" last month. He was advised by Assistant Professor Brittany Hartwell.

Following is an abstract of his dissertation:

While subunit vaccines offer a safe platform for immunization, their inability to persist in lymphoid tissues and target B cells effectively often results in weak and short-lived antibody responses. Rapid systemic clearance and inefficient transport to secondary lymphoid organs currently limit the ability of subunit vaccines to generate robust germinal center responses required for durable immunity. Amphiphile vaccines (amph-vaccines) exploit endogenous albumin trafficking pathways by hitchhiking on albumin to enhance antigen delivery to secondary lymphoid organs, where antigen-specific immune responses are orchestrated. In addition to albumin hitchhiking, some amphiphile conjugates demonstrate a secondary ability to insert their lipid tail into the cell membrane, effectively 'painting' the cells with multivalent antigen. 

In this dissertation, I investigated the structural and physicochemical properties of amphiphile-protein vaccines, focusing on antigen molecular weight and polyethylene glycol (PEG) spacer length, and evaluated their impact on immune activation using HIV-derived immunogens (eOD-GT8 and MD39) as model antigens. Through in vitro membrane insertion and calcium flux assays using a germline-reverted VRC01 (glVRC01) B cell line, alongside in vivo lymphatic trafficking and immunogenicity studies in mice, I compared amphiphile-conjugated proteins against soluble and micellar formats. While both amphiphile ‘painted’ cells and micelles present multivalent antigen, this multimeric display is critical for inducing B cell receptor (BCR) clustering and higher-avidity binding, which amplifies downstream signaling required for robust B cell activation. Our results demonstrate that cell painting, rather than micelle formation, is the predominant driver of the resulting germinal center (GC) activation and humoral immune responses. I conjugated different immunogens with varying MW, including a structurally large native-like trimer, establishing that this membrane-anchoring mechanism can be leveraged across a diverse range of antigens with varying molecular weights. By leveraging the cell painting behavior, amph-MD39 elicited a 4-fold increase in B cell activation in vitro and doubled the frequency of antigen-specific GC B cells in vivo compared to soluble MD39. These results demonstrate that for amhiphile conjugates of a large sterically hindered trimer, multivalent presentation via cell painting was a primary driver of enhanced immunogenicity, independent of lymphatic trafficking. Furthermore, tuning PEG spacer length was shown to modulate this behavior and dictate downstream GC reactions and immune responses. Later, by extending these findings to mucosally relevant nasal-associated lymphoid tissue (NALT), we addressed the challenge of rapid mucociliary clearance in intranasal immunization. 

We demonstrated that by leveraging the membrane-anchoring mechanism, amphiphile vaccines significantly enhanced the uptake and retention of protein antigens within the nasal passage, and achieved superior antigen persistence, leading to more than 2-fold enhancement in GC responses within the nasal-associated lymphoid tissue (NALT), and more than 1000-fold increase in antigen-specific IgA titers within the mucosal washes. Collectively, this work establishes membrane anchoring-mediated antigen persistence and multivalent presentation as a potent, versatile strategy for driving superior B cell activation and durable antibody responses. By redefining the biophysical parameters for engineering smarter amphiphile subunit vaccines, this dissertation provides a blueprint for the development of next-generation vaccine platforms capable of overcoming harsh physiological barriers to combat global infectious pathogens.