genomewide characterization of host-pathogen interactions by ...

mean normalized intensity
mean normalized intensity
Maren Depke
Results
Pathogen Gene Expression Profiling
A
fold change in comparison to
baseline 1 h serum/CO 2 control
S. aureus
RN1HG
sample
conditions
and time
points
fnbA fnbB clfA clfB isaB eap coa vwb emp efb
exponential growth phase -1.8 -2.8 1.6 -1.7 1.3 -2.0 -2.2 -5.8 -1.6 -2.8
2.5 h internalized 6.2 7.0 5.3 2.1 2.1 1.8 6.3 4.9 -1.4 1.9
6.5 h internalized 6.4 3.1 2.8 2.1 -1.3 11.0 1.8 2.7 2.9 2.7
2.5 h serum/CO 2 control 1.1 -2.9 2.5 -1.6 1.5 2.0 -3.6 -7.7 -1.9 -1.3
6.5 h serum/CO 2 control 3.4 -2.0 9.2 -3.3 -2.1 4.7 -5.7 -4.2 -1.6 -1.3
2.5 h anaerobic incubation 1.3 -1.2 3.3 -1.4 4.7 3.1 -2.7 -3.3 1.6 1.2
B
C
10.0
10.0
fnbA
eap
fnbB
coa
clfA
vwb
1.0
clfB
isaB
1.0
emp
efb
0.1
exp.
1 h
co.
2.5 h
int.
6.5 h
int.
2.5 h
co.
6.5 h
co.
2.5 h
anae.
S. aureus RN1HG sample conditions and time points
0.1
exp.
1 h
co.
2.5 h
int.
6.5 h
int.
2.5 h
co.
6.5 h
co.
2.5 h
anae.
S. aureus RN1HG sample conditions and time points
Fig. R.5.14: Adhesins (MSCRAMMs and SERAMs) gene expression.
A. Overview on fold change values relative to the baseline sample “1 h serum/CO 2 control” and on significance in statistical group
comparisons. Differentially expressed genes are marked by gray filling for the corresponding sample condition/time point.
Genes which were significant in statistical testing (p* < 0.05) but did not pass the absolute fold change cutoff 2 are indicated in bold
without filling. The sample “6.5 h serum/CO 2 control” could not be included in statistical testing because of small group size (n = 2).
B, C. Overview on mean normalized gene expression intensity for MSCRAMM (B) and SERAM (C) genes. After the global normalization
by inter-chip scaling and detrending, each individual gene has been normalized to the expression level of the baseline sample “1 h
serum/CO 2 control”. Although not being continuous data, values were depicted as line graphs instead of bar charts for better facility
of inspection.
(exp. − exponential growth phase; 1 h co. – 1 h serum/CO 2 control; 2.5 h int. − 2.5 h internalization; 6.5 h int. − 6.5 h internalization;
2.5 h co. − 2.5 h serum/CO 2 control; 6.5 h co. − 6.5 h serum/CO 2 control; 2.5 h anae. − 2.5 h anaerobic incubation)
Toxins, especially lytic toxins, are one of the most outstanding groups of virulence factors
because they directly harm the host cells. In the group of toxins, two bicomponent toxin gene
pairs were observed to be induced in internalized staphylococci: lukD/lukE and hlgB/hlgC.
Furthermore, alpha-hemolysin (hla) was induced. Induction for all genes was significant at the
6.5 h time point except for hlgB, which was not significant although its fold change was the
second highest in this group. The pair hlgB/hlgC was additionally already induced in internalized
staphylococci 2.5 h after start of infection, and also in the 2.5 h serum/CO 2 control. Again, the
6.5 h serum/CO 2 control exhibited an even further increased fold change, but could not be tested
statistically (Fig. R.5.15 A, B).
Further virulence factors, secreted and membrane bound enzymes, were observed with
divergent expression pattern in internalized staphylococci. All six members A, B, C, D, E, F of the
spl operon, coding for serine proteases with similarity to the V8 protease, were found to be
induced at the 6.5 h time point of internalization. Four of them, A, B, C, and E, were additionally
induced 2.5 h after start of infection. For this operon, a similar induction was observed in the
serum/CO 2 control samples. Another exoenzyme, lipase (lip), was induced in internalized
staphylococci, but the peak of induction occurred 2.5 h after start of infection, i. e. earlier than
for the spl operon. In serum/CO 2 control, lip gene expression did not change after 2.5 h, but a
strong induction was detectable after 6.5 h although statistical testing was not possible
(Fig. R.5.16 A, B). A second group of enzymes exhibited repression in internalized staphylococci:
hysA (hyaluronate lyase), htrA (serine protease, a membrane bound enzyme), nuc (nuclease), and
sspA (glutamyl endopeptidase, V8 peptidase).
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