Brucella requires a functional Type IV secretion system to elicit innate immune responses in mice.
The virB operon, encoding a Type IV secretion system (T4SS), is essential for intracellular survival and persistent infection by Brucella spp. To better understand the role of the T4SS in evading host defence mechanisms and establishing chronic infection, we compared transcriptional profiles of the host response to infection with wild-type and virB mutant Brucella strains. Analysis of gene expression profiles in murine splenocytes 3 days after inoculation with wild-type Brucella strains revealed an inflammatory response, with a prominent upregulation of genes induced by both type I and type II interferons. Real-time RT-PCR showed that a group of genes from these pathways were induced by day 3 post infection and declined to baseline levels by day 7. In contrast, neither of the two virB mutant strains elicited a proinflammatory gene expression profile, demonstrating that the T4SS was required to trigger this response. Infection studies using type I interferon receptor knockout mice showed that a lack of type I interferon signalling did not affect Brucella replication during the first 4 weeks of infection. Thus, induction of type I interferons does not appear to be an essential mechanism by which the T4SS promotes persistent infection by Brucella.
Roux
Christelle M
CM
Department of Medical Microbiology and Immunology, University of California at Davis, Davis, CA, USA.
Rolán
Hortensia G
HG
Santos
Renato L
RL
Beremand
Phillip D
PD
Thomas
Terry L
TL
Adams
L Garry
LG
Tsolis
Renée M
RM
D000818:Animals; D001426:Bacterial Proteins / Q000276:immunology* / Q000378:metabolism; D002003:Brucella abortus / Q000276:immunology / Q000472:pathogenicity*; D017347:Brucella melitensis / Q000276:immunology / Q000472:pathogenicity; D002006:Brucellosis / Q000276:immunology* / Q000382:microbiology; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D007372:Interferons / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D013154:Spleen / Q000166:cytology / Q000276:immunology
D001426:Bacterial Proteins; D011506:Proteins; D007372:Interferons