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Meeting Abstract

P3-122   -   Chronic infection improves tolerance and resistance in Drosophila melanogaster Wukitch, AM*; Patel, A; Satriale, F; Chambers, MC; Bucknell University; Bucknell University; Penn State School of Medicine; Bucknell University

Chronic infections are the result of pathogens persisting in the body. While chronic infections can have negative consequences, they sometimes provide protection against future infections. In the model organism Drosophila melanogaster, the common fruit fly, chronic infection reduces mortality after distinct secondary infections compared to singly infected flies. We hypothesized the reduced mortality was due to improved resistance, the ability to kill a pathogen, and/or improved tolerance, the ability to minimize pathogen damage. We infected flies with Serratia marcescens to induce chronic infection, then with a different bacteria for secondary infection, and found enhanced resistance and tolerance compared to control flies only injected with the second bacteria. Chronically infected flies had reduced bacterial loads 10 hours post secondary infection compared to control flies given the same secondary infectious dose indicating improved resistance. At similar bacterial loads, chronically infected flies were more likely to survive, indicating improved tolerance compared to control flies. We further hypothesized that antimicrobial peptide (AMP) gene expression is responsible for the increased resistance. Previous work shows chronically infected flies exhibit AMP upregulation and we found that there is a minimum dose necessary to establish a protective chronic infection. This supports our hypothesis as lower bacterial loads are predicted to induce lower AMP expression. We further predict that chronically infected flies may induce a more robust AMP response after secondary infection and are directly testing this by measuring AMP gene expression after secondary infection using qRT-PCR. We also predict that flies without antimicrobial peptides will not exhibit chronic infection induced protection during secondary infection and are testing this using flies that have subsets of AMP genes deleted.