The possible influence of LuxS in the in vivo virulence of rabbit enteropathogenic Escherichia coli.
Attaching and effacing (A/E) organisms, such as rabbit enteropathogenic Escherichia coli (EPEC), human EPEC or enterohemorrhagic E. coli (EHEC) share attaching and effacing phenotype and LEE pathogenicity island responsible for A/E. The present study was undertaken to investigate the impact of the LuxS quorum sensing (QS) signaling system in vitro and in vivo pathogenicity of A/E organisms using rabbit EPEC (rEPEC) strain E22 (O103:H2). Analysis of the bioluminescence indicated abolished production of the QS signal AI-2 by luxS mutant (E22DeltaluxS). Strain E22Deltalux also exhibited impaired expression of several normally secreted proteins and reduced adherence to cultured HeLa cells. Complementation of the intact luxS gene to E22DeltaluxS restored secreted protein expression comparable to the WT type but not adherence to HeLa cells. In experimentally infected rabbits, the isogenic luxS mutant induced clinical illness and intimate adherence to the intestinal mucosa, albeit to a less extent, comparable to that seen with the parent virulent strain. It is worth noting that reduced fecal bacterial shedding, mucosal adherence and improved cumulative weight gain were seen for the mutant strain complemented with luxS when compared to the WT. It appears that the luxS gene is not essential for in vivo pathogenicity by rEPEC where exogenous QS signals are present in the gut. The impact of AI-2 provided by multicopy plasmid on bacterial virulence is discussed.
Zhu
Chengru
C
Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA. czhu@salud.unm.edu
Feng
Shuzhang
S
Sperandio
Venessa
V
Yang
Zhuolu
Z
Thate
Timothy E
TE
Kaper
James B
JB
Boedeker
Edgar C
EC
D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology; D001426:Bacterial Proteins / Q000502:physiology*; D013437:Carbon-Sulfur Lyases / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics; D054308:Enteropathogenic Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000503:physiopathology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D006367:HeLa Cells; D006714:Homoserine / Q000031:analogs & derivatives / Q000502:physiology; D006801:Humans; D007410:Intestinal Diseases / Q000382:microbiology* / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000382:microbiology; D007783:Lactones; D008297:Male; D016254:Mutagenesis, Insertional; D053038:Quorum Sensing / Q000502:physiology; D011817:Rabbits; D014774:Virulence / Q000502:physiology
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria