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Systemic Bacterial Infection and Immune Defense Phenotypes in Drosophila Melanogaster
Published on: May 13, 2015
Consequences of chronic bacterial infection in Drosophila melanogaster
Moria Cairns Chambers1,2, Eliana Jacobson1, Sarah Khalil1
1Department of Entomology, Cornell University, Ithaca, New York, United States of America.
Abstract:
Even when successfully surviving an infection, a host often fails to eliminate a pathogen completely and may sustain substantial pathogen burden for the remainder of its life. Using systemic bacterial infection in Drosophila melanogaster, we characterize chronic infection by three bacterial species from different genera - Providencia rettgeri, Serratia marcescens, and Enterococcus faecalis-following inoculation with a range of doses. To assess the consequences of these chronic infections, we determined the expression of antimicrobial peptide genes, survival of secondary infection, and starvation resistance after one week of infection. While higher infectious doses unsurprisingly lead to higher risk of death, they also result in higher chronic bacterial loads among the survivors for all three infections. All three chronic infections caused significantly elevated expression of antimicrobial peptide genes at one week post-infection and provided generalized protection again secondary bacterial infection. Only P. rettgeri infection significantly influenced resistance to starvation, with persistently infected flies dying more quickly under starvation conditions relative to controls. These results suggest that there is potentially a generalized mechanism of protection against secondary infection, but that other impacts on host physiology may depend on the specific pathogen. We propose that chronic infections in D. melanogaster could be a valuable tool for studying tolerance of infection, including impacts on host physiology and behavior.
Insights
Chronic bacterial infections in fruit flies (Drosophila melanogaster) lead to higher pathogen loads but also enhanced immunity to secondary infections. However, impacts on host physiology, like starvation resistance, vary by pathogen species.
Area of Science:
- * Microbiology and Immunology
- * Infectious Disease Research
- * Model Organism Studies
Background:
- * Hosts often fail to clear pathogens completely, leading to chronic infections.
- * Chronic infections can impact host physiology and survival.
- * Understanding host-pathogen interactions in chronic states is crucial.
Purpose of the Study:
- * To characterize chronic bacterial infections in Drosophila melanogaster using three distinct bacterial species.
- * To assess the consequences of chronic infection on host immunity and physiology.
- * To evaluate Drosophila melanogaster as a model for studying infection tolerance.
Main Methods:
- * Systemic bacterial infection of Drosophila melanogaster with Providencia rettgeri, Serratia marcescens, and Enterococcus faecalis at various doses.
- * Measurement of antimicrobial peptide gene expression one week post-infection.
- * Assessment of survival against secondary bacterial infection and starvation resistance.
Main Results:
- * Higher infectious doses correlated with increased chronic bacterial loads in survivors.
- * All three chronic infections elevated antimicrobial peptide gene expression and conferred protection against secondary infection.
- * Only Providencia rettgeri infection reduced starvation resistance in persistently infected flies.
Conclusions:
- * Drosophila melanogaster exhibits a generalized protective response against secondary infections during chronic bacterial infections.
- * Specific pathogen-host interactions dictate physiological consequences, such as starvation resistance.
- * Chronic infections in Drosophila melanogaster offer a valuable model for studying infection tolerance and its broader physiological impacts.
