![]() ![]() reported sequencing the bft gene from ETBF strain VPI 13784 (lamb isolate) ( 16). fragilis toxin gene ( bft) from a cosmid library of ETBF strain 86- (piglet isolate) ( 9) and, at the same time, Kling et al. We recently reported cloning and sequencing the B. This toxin stimulates fluid accumulation in lamb ligated ileal loops (LLIL) and alters the morphology of human intestinal epithelial cells in vitro, especially HT29/C1 cells ( 3, 17, 27, 30, 40, 49). The primary virulence factor proposed for these strains is a zinc-dependent metalloprotease toxin ( B. ETBF strains may have evolved by horizontal transfer of these two genetic elements into a pattern II NTBF strain.Įnterotoxigenic Bacteroides fragilis (ETBF) strains have been associated with watery diarrheal disease in livestock and young children ( 27, 28, 34, 35, 38, 40). fragilis chromosome (42%), suggesting that the BfPAI and its flanking region are two distinct genetic elements originating from very different organisms. The G+C content of the BfPAI (35%) and the flanking DNA (47 to 50%) differ greatly from that reported for the B. ![]() This result defined the BfPAI as being 6,036 bp in length and its precise integration site as being between the bfmB and bfmC stop codons. Comparison of this sequence with the appropriate sequence of ETBF strain 86- showed that in this ETBF strain the 16-bp sequence is replaced by the BfPAI. Nucleotide sequence analysis of one NTBF pattern III strain (strain I-1345) revealed that bfmB and bfmC are adjacent to each other and separated by a 16-bp GC-rich sequence. The region flanking the right end of the BfPAI contains a gene ( bfmC) whose predicted protein shares significant identity to the TraD mobilization proteins encoded by plasmids F and R100 from Escherichia coli. The nucleotide sequence flanking the left end of the BfPAI revealed a region with the same organization as the mobilization region of the 5-nitroimidazole resistance plasmid pIP417 and the clindamycin resistance plasmid pBFTM10, that is, two mobilization genes ( bfmA and bfmB) organized in one operon and a putative origin of transfer ( oriT) located in a small, compact region. Of 191 NTBF strains, 100 (52%) lack both the BfPAI and at least a 12-kb region flanking BfPAI (pattern II), and 82 of 191 NTBF strains (43%) lack the BfPAI but contain the flanking region (pattern III). fragilis pathogenicity island or BfPAI) which is present exclusively in all 113 ETBF strains tested (pattern I). fragilis (NTBF) strains, we found that bft and a second metalloprotease gene ( mpII) are contained in an ∼6-kb pathogenicity island (termed B. Studying a collection of ETBF and nontoxigenic B. ![]() Enterotoxigenic Bacteroides fragilis (ETBF) strains, which produce a 20-kDa zinc metalloprotease toxin (BFT), have been associated with diarrheal disease in animals and young children. ![]()
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