title: In vivo expression of the heat stable (estA) and heat labile (eltB) toxin genes of enterotoxigenic Escherichia coli (ETEC).
abstract: Enterotoxigenic Escherichia coli (ETEC) colonize the intestine and adhere to the epithelium by means of different host specific colonization factors (CFs). Colonizing ETEC produce one or both of two enterotoxins; the heat stable (ST) and heat labile (LT) toxins which are both able to cause diarrhoea. The regulation of virulence genes in ETEC during infection of the human intestine is mainly unknown. In this study we analysed the level of mRNA expression of estA, coding for ST, and eltB, coding for the B subunit of LT, during human infection. The expressions of the toxins in ETEC strains expressing both ST and LT were investigated in bacteria isolated directly from patient stool without sub-culturing, (in vivo) and compared to the expression pattern of the corresponding ST/LT strains grown in liquid broth (in vitro) by quantitative competitive RT-PCR using fluorescent primers. We found that estA and eltB are expressed in the in vivo samples but no significant up-or down regulation of the expression levels of either estA or eltB could be determined in vivo as compared to in vitro.
authors.affiliation: Institute of Biomedicine, Department of Microbiology and Immunology, Göteborg University, Box 435, 405 30 Göteborg, Sweden. asa.sjoling@microbio.gu.se
authors.forename: Asa
authors.initials: A
authors.lastname: Sjöling
authors.forename: Firdausi
authors.initials: F
authors.lastname: Qadri
authors.forename: Matilda
authors.initials: M
authors.lastname: Nicklasson
authors.forename: Yasmin Ara
authors.initials: YA
authors.lastname: Begum
authors.forename: Gudrun
authors.initials: G
authors.lastname: Wiklund
authors.forename: Ann-Mari
authors.initials: AM
authors.lastname: Svennerholm
mesh_terms: D000222:Adaptation, Physiological; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000235:genetics*; D003967:Diarrhea / Q000382:microbiology; D004768:Enterotoxins / Q000096:biosynthesis / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D037521:Virulence Factors; C034151:heat stable toxin (E coli); C027538:heat-labile enterotoxin, E coli