Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Thornton, Justin A.

Committee Member

Jordan, Heather

Committee Member

Seo, Ken Seok

Date of Degree

5-1-2020

Original embargo terms

Worldwide

Document Type

Graduate Thesis - Open Access

Major

Biological Sciences

Degree Name

Master of Science

College

College of Arts and Sciences

Department

Department of Biological Sciences

Abstract

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.

URI

https://hdl.handle.net/11668/16948

Comments

Pneumococcus||Neutrophils||Granules||Resistance||Capsule||HtrA

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