[Effect of clpE gene deletion on virulence of Streptococcus pneumoniae].
OBJECTIVE
To study the effect of clpE gene deletion on the virulence of Streptococcus pneumoniae.


METHODS
The clpE-deficient strain was constructed by LFH-PCR and identified by PCR and sequencing. The impact of clpE mutant on the virulence of S. pneumoniae was evaluated in a mouse model. In addition,we also studied the effect of clpE mutant on adherence and invasion of host cells. Real time RT-PCR was used to measure the mRNA expression levels of autolysin A, pneumococcal surface adhesion A, pneumolysin, pneumococcal surface protein A and neuraminidase.


RESULTS
The clpE gene was replaced completely by erm cassette. Mice virulence experiments showed that the median lethal time of the wide-type was 54 h, whereas that of clpE mutant was 21d (P < 0.01). Cell culture infection experiments indicated that adherence and invasion of clpE mutant were strongly reduced (P < 0.05). The expression of virulent factors in clpE mutant was lower than that of the wild-type (P < 0.05).


CONCLUSIONS
ClpE is involved in virulence by modulating the expressions of virulence factors.
Zhang
Qun
Q
Key Laboratory of Medical Diagnostics, Ministry of Education, Chongqing Medical University, Chongqing 400016, China. zhangqun198166@163.com
Yin
Nanlin
N
Xu
Wenchun
W
Wang
Hong
H
Pang
Dan
D
Yang
Xiaoliang
X
Yin
Yibing
Y
Zhang
Xuemei
X
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011008:Pneumococcal Infections / Q000382:microbiology / Q000401:mortality*; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D037521:Virulence Factors; D000251:Adenosine Triphosphatases; C118340:ClpE protein, bacteria