The alternative sigma factor B modulates virulence gene expression in a murine Staphylococcus aureus infection model but does not influence kidney gene expression pattern of the host.
Infections caused by Staphylococcus aureus are associated with significant morbidity and mortality and are an increasing threat not only in hospital settings. The expression of the staphylococcal virulence factor repertoire is known to be affected by the alternative sigma factor B (SigB). However, its impact during infection still is a matter of debate. Kidney tissues of controls or mice infected with S. aureus HG001 or its isogenic sigB mutant were analyzed by transcriptome profiling to monitor the host response, and additionally expression of selected S. aureus genes was monitored by RT-qPCR. Direct transcript analysis by RT-qPCR revealed significant SigB activity in all mice infected with the wild-type strain, but not in its isogenic sigB mutant (p<0.0001). Despite a clear-cut difference in the SigB-dependent transcription pattern of virulence genes (clfA, aur, and hla), the host reaction to infection (either wild type or sigB mutant) was almost identical. Despite its significant activity in vivo, loss of SigB did neither have an effect on the outcome of infection nor on murine kidney gene expression pattern. Thus, these data support the role of SigB as virulence modulator rather than being a virulence determinant by itself.
Interfaculty Institute for Genetics and Functional Genomics, Ernst-Moritz-Arndt-University Greifswald, Germany.
Maren
M
Depke
Marc
M
Burian
Tina
T
Schäfer
Barbara M
BM
Bröker
Knut
K
Ohlsen
Uwe
U
Völker
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004195:Disease Models, Animal; D005260:Female; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics; D006790:Host-Parasite Interactions; D007668:Kidney / Q000378:metabolism* / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D012329:RNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; C079011:SigB protein, Bacteria; D012808:Sigma Factor