Transcriptional profiling of Bacillus anthracis during infection of host macrophages.
The interaction between Bacillus anthracis and the mammalian phagocyte is one of the central stages in the progression of inhalational anthrax, and it is commonly believed that the host cell plays a key role in facilitating germination and dissemination of inhaled B. anthracis spores. Given this, a detailed definition of the survival strategies used by B. anthracis within the phagocyte is critical for our understanding of anthrax. In this study, we report the first genome-wide analysis of B. anthracis gene expression during infection of host phagocytes. We developed a technique for specific isolation of bacterial RNA from within infected murine macrophages, and we used custom B. anthracis microarrays to characterize the expression patterns occurring within intracellular bacteria throughout infection of the host phagocyte. We found that B. anthracis adapts very quickly to the intracellular environment, and our analyses identified metabolic pathways that appear to be important to the bacterium during intracellular growth, as well as individual genes that show significant induction in vivo. We used quantitative reverse transcription-PCR to verify that the expression trends that we observed by microarray analysis were valid, and we chose one gene (GBAA1941, encoding a putative transcriptional regulator) for further characterization. A deletion strain missing this gene showed no phenotype in vitro but was significantly attenuated in a mouse model of inhalational anthrax, suggesting that the microarray data described here provide not only the first comprehensive view of how B. anthracis survives within the host cell but also a number of promising leads for further research in anthrax.
Bergman
Nicholas H
NH
Bioinformatics Program and Department of Microbiology & Immunology, University of Michigan Medical School, 6706 Medical Sciences Bldg. II, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0620, USA. niber@umich.edu
Anderson
Erica C
EC
Swenson
Ellen E
EE
Janes
Brian K
BK
Fisher
Nathan
N
Niemeyer
Matthew M
MM
Miyoshi
Amy D
AD
Hanna
Philip C
PC
D000818:Animals; D000881:Anthrax / Q000382:microbiology; D001408:Bacillus anthracis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D008811:Mice, Inbred DBA; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D012329:RNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014132:Trachea / Q000382:microbiology; D014158:Transcription, Genetic; D014774:Virulence
D001426:Bacterial Proteins; D012329:RNA, Bacterial