Date of Thesis

Spring 2019

Thesis Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science

Major

Cell Biology/Biochemistry

Minor, Emphasis, or Concentration

Classics & Mediterranean Studies

First Advisor

Dr. Moria Chambers

Second Advisor

Dr. Charles Clapp

Third Advisor

Dr. Ellen Herman

Keywords

Drosophila, tolerance, resistance, chronic infection

Abstract

The use of non-mammalian infection models like Drosophila melanogaster has made it easier to study bacterial pathogenesis. D. melanogaster proves to be an excellent model in that the innate immunity pathways and tissue physiology of this organism are very similar to those of mammals (Kounatidis and Ligoxygakis, 2012). Bacterial pathogenesis can prove to be lethal when the microbe is injected into the thorax of the fly (Chambers et al., 2014), but our lab has found that microbes lingering from a previous pathogenic infection can provide significant protection against future acute infection.

This project considers three approaches to understanding the effects of the survival benefit conferred by chronic infection: secondary infection using a single dose, secondary infection using a range of doses, and the prospect of using fluorescence microscopy. The project aimed to distinguish whether this benefit was due to an increase in tolerance or resistance to infection. Experiments involved chronic infection of D. melanogaster with Providencia rettgeri, Serratia marcescens, or Enterococcus faecalis, and used Providencia rettgeri exclusively at secondary infection. Results suggest that the protective benefit conferred by chronic S. marcescens infection is due to a combination of both tolerance and resistance. It is not clear if there is a significant benefit to having a chronic infection with E. faecalis. Ongoing research is focused on determining the mechanism behind this improved tolerance and resistance. This includes work with known tolerance mutants and experiments to determine whether localization of the secondary infection is altered by chronic infection using fluorescence microscopy.

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