Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name

M. Eng.


Chemical Engineering

Committee Chair

Willing, Gerold A.


Virus diseases; Respiratory infections


Respiratory syncytial virus is the leading cause of lower respiratory tract infection in infants and currently lacks an effective vaccine or treatment beyond symptom relief. The atomic force microscope is particularly well suited for imaging biological samples including DNA, proteins, cells, and viral activity. Analyzing fixed HEp-2 cells with the AFM after infection and incubation with RSV for periods up to 24 hrs reveals several physical changes that may lead to a better understanding of the viral effects on living cells. Comparing cells fixed with methanol or glutaraldehyde and osmium tetroxide suggests substantial volume losses in the cells regardless of the fixatives used. Suggested mechanisms for the volume decrease include a combination of the creation of an osmotic pressure gradient within the cell and overall cellular collapse. Elastic modulus calculations were performed on the fixed cells at each duration of infection and analyzed for correlations to other physical properties. Hydrophobic interaction forces were also measured and analyzed in order to characterize chemical changes to the cell membrane. It was found that the elastic modulus did not decrease throughout the entire infection for up to 24 hours, but the hydrophobic expression on the cell surface steadily decreased over this same period. This decrease is attributed to the rapid removal and repair of the cell membrane by the RSV virions during exocytosis. Based on this study on methanol fixed cells, it was confirmed that RSV infection does not appear to modify the actin cytoskeleton of human cells.