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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED APPROACHES FOR PROTECTION OF ANIMALS FROM VECTOR-BORNE PATHOGENS

Location: Arthropod-Borne Animal Diseases Research

Title: Pseudomonas aeruginosa in Musca domestica L.: temporospatial examination of bacteria population dynamics and house fly antimicrobial responses

Authors
item Joyner, Chester -
item Mills, Mary -
item Nayduch, Dana

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 27, 2013
Publication Date: November 18, 2013
Citation: Joyner, C.J., Mills, M.K., Nayduch, D. 2013. Pseudomonas aeruginosa in Musca domestica L.: temporospatial examination of bacteria population dynamics and house fly antimicrobial responses. PLoS One. 8(11): e79224. doi:10.1371/journal.pone.0079224.

Interpretive Summary: Bacteria ingested by adult flies enter the digestive tract and face a hostile environment including antimicrobial defenses. Because the outcome of this interaction impacts bacterial survival and dissemination, our primary objective was to understand the dynamic association between house flies and ingested bacteria over time. We concurrently examined the fate of green fluorescent protein (GFP)-expressing Pseudomonas aeruginosa (GFP-P. aeruginosa) in the house fly gut along with antimicrobial peptide (AMP) gene and protein expression. Motile, viable GFP-P. aeruginosa were found in all regions of the gut and were culturable throughout the observation period (2-24 h). A significant decrease in recoverable bacteria occurred between 2-12 h, followed by an increase between 12 and 24 h. The antimicrobial genes cecropin, diptericin, and defensin were upregulated both locally (gut) and systemically in the body of flies. Furthermore, these genes were induced in all tissues of the gut, which correlated with the presence of bacteria in those same regions. Interestingly, the decrease in recoverable P. aeruginosa was associated with a peak in the antimicrobial gene products (proteins) in the gut, which implies that these products may be involved in killing bacteria. Flies excreted GFP-P. aeruginosa in feces and vomit throughout the 24 h period, serving as both reservoirs and disseminators of this bacterium. Collectively, our data show that flies can harbor and transmit P. aeruginosa, and that the interactions of fly defenses with bacteria can influence vector competence.

Technical Abstract: House flies associate with microbes throughout their life history. Bacteria ingested by adult flies enter the alimentary canal and face a hostile environment including antimicrobial defenses. Because the outcome of this interaction impacts bacterial survival and dissemination, our primary objective was to understand the temporospatial dynamics of fly-bacteria associations. We concurrently examined the temporospatial fate of GFP-expressing Pseudomonas aeruginosa (GFP-P. aeruginosa) in the house fly alimentary canal along with antimicrobial peptide (AMP) expression. Motile, viable GFP-P. aeruginosa were found in all regions of the alimentary canal and were culturable throughout the observation period (2-24 h). A significant decrease in recoverable bacteria occurred between 2-12 h, followed by an increase between 12 and 24 h. qRT-PCR analysis showed expression of the AMPs cecropin, diptericin, and defensin both locally (gut) and systemically. Furthermore, mRNA of all AMPs were expressed throughout gut tissues, with some tissue-specific temporal variation. Interestingly, fluctuation in recoverable P. aeruginosa was associated with peak AMP protein expression in the gut (immunofluorescent signal detection), but not with mRNA (qRTPCR). In regards to vector competence, flies excreted GFP-P. aeruginosa throughout the 24 h period, serving as both reservoirs and disseminators of this bacterium. Collectively, our data show flies can harbor and disseminate P. aeruginosa, and that the interactions of fly defenses with bacteria can

Last Modified: 11/26/2014
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