Abstract

Influenza A virus (IAV) remains a significant global health challenge. IAV utilizes the receptor binding protein hemagglutinin (HA) and the receptor destroying protein neuraminidase (NA) to facilitate infection. The activities of these proteins affect multiple steps in IAV life cycle. However, it remains unclear how these IAV factors influence infection dynamics in the context of a complex cellular environment encountered in the respiratory tract. In this work, we use fluorescence microscopy and human airway epithelial cells to study influenza biology at the single-cell and single-virion level, revealing key insights into viral binding, entry, and spread. First, we focused on the cellular determinants of HA proteolytic activation. This process is essential for enabling HA to mediate viral entry. Using immunofluorescence, we observed cell-to-cell variability in HA activation efficiency. This offers a mechanistic explanation for the efficient yet incomplete activation observed at the population level. These results suggest that not all virions produced within a host cell population are equally infectious, highlighting the role of cellular factors in shaping viral fitness and infectivity. Second, we studied the role of NA activity during virus spread and discovered its ability to optimize the efficiency of viral transmission by cleaving the viral receptor at the infection sites. This allows the virus to seed productive infections locally while maximizing its potential to spread distantly. Lastly, we investigated how ciliated cells contribute to virus binding in human airway epithelia. By characterizing infections in samples from donors with primary ciliary dyskinesia (PCD), we found that ciliary beating is essential for IAV to reach the cell body of the ciliated cells for infection, while enhancing binding to other cell types. Beyond the investigation at single-cell and single-virion level, we pursued studies on molecular orientation and flexibility at single molecule level to elucidate how protein dynamics affect the interactions between influenza protein and antibody. Collectively, these research projects advance our understanding of influenza virus biology by leveraging cutting-edge imaging technologies to unravel key aspects of host-pathogen interactions.

Committee Chair

Michael Vahey

Degree

Doctor of Philosophy (PhD)

Author's Department

Biomedical Engineering

Author's School

McKelvey School of Engineering

Document Type

Dissertation

Date of Award

7-29-2025

Language

English (en)

Download

Share

COinS