<it>Coxiella burnetii </it>Nine Mile II proteins modulate gene expression of monocytic host cells during infection

• Main Authors: Shaw Edward I, Ayoubi Patricia, Mahapatra Saugata
• Format: Article
• Language: English
• Published: BMC 2010-09-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/10/244

<p>Abstract</p> <p>Background</p> <p><it>Coxiella burnetii </it>is an intracellular bacterial pathogen that causes acute and chronic disease in humans. Bacterial replication occurs within enlarged parasitophorous vacuoles (PV) of eukaryotic cells, the biogenesis and maintenance of which is dependent on <it>C. burnetii </it>protein synthesis. These observations suggest that <it>C. burnetii </it>actively subverts host cell processes, however little is known about the cellular biology mechanisms manipulated by the pathogen during infection. Here, we examined host cell gene expression changes specifically induced by <it>C. burnetii </it>proteins during infection.</p> <p>Results</p> <p>We have identified 36 host cell genes that are specifically regulated when <it>de novo </it><it>C. burnetii </it>protein synthesis occurs during infection using comparative microarray analysis. Two parallel sets of infected and uninfected THP-1 cells were grown for 48 h followed by the addition of chloramphenicol (CAM) to 10 μg/ml in one set. Total RNA was harvested at 72 hpi from all conditions, and microarrays performed using Phalanx Human OneArray™ slides. A total of 784 (mock treated) and 901 (CAM treated) THP-1 genes were up or down regulated ≥2 fold in the <it>C. burnetii </it>infected vs. uninfected cell sets, respectively. Comparisons between the complementary data sets (using >0 fold), eliminated the common gene expression changes. A stringent comparison (≥2 fold) between the separate microarrays revealed 36 host cell genes modulated by <it>C. burnetii </it>protein synthesis. Ontological analysis of these genes identified the innate immune response, cell death and proliferation, vesicle trafficking and development, lipid homeostasis, and cytoskeletal organization as predominant cellular functions modulated by <it>C. burnetii </it>protein synthesis.</p> <p>Conclusions</p> <p>Collectively, these data indicate that <it>C. burnetii </it>proteins actively regulate the expression of specific host cell genes and pathways. This is in addition to host cell genes that respond to the presence of the pathogen whether or not it is actively synthesizing proteins. These findings indicate that <it>C. burnetii </it>modulates the host cell gene expression to avoid the immune response, preserve the host cell from death, and direct the development and maintenance of a replicative PV by controlling vesicle formation and trafficking within the host cell during infection.</p>