BioE PhD Defense Presentation- Nikki McArthur

Advisor: Ravi Kane, Ph.D. (Chemical and Biomolecular Engineering) 

Committee Members: 

John Blazeck, Ph.D. (Chemical and Biomolecular Engineering) 

Julie Champion, Ph.D. (Chemical and Biomolecular Engineering) 

Corey Wilson, Ph.D. (Chemical and Biomolecular Engineering) 

Levi Wood, Ph.D. (Mechanical Engineering)  

Engineering Multivalent Nanobodies Against Amyloid Proteins and Other Antigens

      Tauopathies, such as Alzheimer’s disease, are neurodegenerative diseases that involve the misfolding and deposition of aggregates of the amyloid protein tau. These diseases are among the most widespread neurodegenerative diseases, yet there are few safe and effective disease-modifying treatments for them. Conformational antibodies and antibody fragments that target the various aggregate forms of tau are promising candidates for treatments to slow the progression of these tauopathies and are useful as reagents to understand the aggregation of tau and its role in disease progression. In this dissertation, we have explored the in vitro development and characterization of multivalent nanobodies, or single-domain antibody fragments, targeting complex and heterogeneous tau aggregates.

      We began with the development of a simple approach using a synthetic yeast surface display nanobody library and in vitro cell sorting to identify a pan-tau nanobody with specificity for tau protein relative to other amyloid proteins. We have shown that multivalent versions of our lead tau-binding nanobody have increased avidity towards tau aggregates and recognize pathogenic tau found in the brains of tau transgenic mice. We have also characterized tau fibril-specific nanobodies and modified them for improved delivery past the blood-brain barrier. Next, we modified our sorting strategy to generate conformational nanobodies that target oligomeric tau, a form of aggregated tau which is suspected to be the most toxic form present in Alzheimer’s disease. We demonstrated that our nanobodies are specific for tau oligomers relative to tau monomer and fibrils and bind to tau oligomers in brain samples from Alzheimer’s disease patients. We have extended this work to screen for nanobodies that target oligomers of another amyloid protein involved in Alzheimer’s disease, amyloid-β. Finally, we applied our in vitro antibody discovery strategies to target an antigen involved in infectious disease—the spike protein of the SARS-CoV-2 virus. We created multivalent nanobodies that bind with high affinity to the XBB spike protein and provide protection against an XBB challenge in mice.

      Overall, this work demonstrates significant progress in the development and characterization of nanobodies specific for complex multimeric antigens. The multivalent nanobodies that we have generated can be used to study amyloid proteins and their involvement in neurodegenerative disease progression and can be further engineered into potent therapies for neurodegenerative or infectious diseases.

https://gatech.zoom.us/j/98028112546?pwd=Z8sNubJKxIZUoaJnJgAaJvsCHex2wo.1