Thornton, Justin A.
Seo, Ken Seok
Date of Degree
Original embargo terms
Visible to MSU only for 6 months||forever||12/15/2020
Graduate Thesis - Open Access
Master of Science
College of Arts and Sciences
Department of Biological Sciences
Streptococcus pneumoniae is a significant human pathogen and the leading cause of community-acquired pneumonia and acute otitis media. One of the primary defense mechanisms of the human immune system against pneumococcal infection involves granule-mediated killing of bacterial cells by neutrophils. While this mechanism has previously been shown to kill about half of pneumococci in vitro, we hypothesized that some pneumococcal strains have evolved to be more resistant to this granule-mediated killing. Clinical isolates demonstrated a varying range of sensitivity to neutrophil granules. Additionally, we established that the absence of the capsule may affect sensitivity as unencapsulated isolates showed a higher average survival than encapsulated isolates. Finally, pneumococcal surface protease HtrA was found to potentially serve as a protective factor as many knockouts were more sensitive than the wildtypes, recombinant HtrA protected wildtype TIGR4, and a resistant isolate showed higher htrA expression levels than sensitive isolates.
Jackson, James Howard, "Pneumococcal resistance to granule-mediated killing by human neutrophils" (2020). Theses and Dissertations MSU. 3553.