biostudies-literatureUnknown38(2)Scotto d'Abusco ASEnterotoxigenic Bacteroides fragilis (ETBF) strains are associated with diarrheal disease in children. These strains produce a zinc metalloprotease enterotoxin, or fragilysin, that can be detected by a cytotoxicity assay with HT-29 cells. Recently, three different isoforms or variants of the enterotoxin gene, designated bft-1, bft-2, and bft-3, have been identified and sequenced. We used restriction fragment length polymorphism analysis of the PCR-amplified enterotoxin gene to detect the isoforms bft-1 and bft-2 or bft-3 borne by ETBF. By sequencing the portion of the bft gene corresponding to the mature toxin in some strains and applying allele-specific PCR for strains categorized as bft-2 or bft-3, we found in our collection two strains harboring bft-3, a variant that had been described Journal of clinical microbiology607-12https://www.ebi.ac.uk/biostudies/studies/S-EPMC86157biostudies-literatureThe alleles of the bft gene are distributed differently among enterotoxigenic Bacteroides fragilis strains from human sources and can be present in double copies.PMC86157Covacci ACensini SScotto d'Abusco ASPantosti ADel Grosso MfalseThe alleles of the bft gene are distributed differently among enterotoxigenic Bacteroides fragilis strains from human sources and can be present in double copies.Enterotoxigenic Bacteroides fragilis (ETBF) strains are associated with diarrheal disease in children. These strains produce a zinc metalloprotease enterotoxin, or fragilysin, that can be detected by a cytotoxicity assay with HT-29 cells. Recently, three different isoforms or variants of the enterotoxin gene, designated bft-1, bft-2, and bft-3, have been identified and sequenced. We used restriction fragment length polymorphism analysis of the PCR-amplified enterotoxin gene to detect the isoforms bft-1 and bft-2 or bft-3 borne by ETBF. By sequencing the portion of the bft gene corresponding to the mature toxin in some strains and applying allele-specific PCR for strains categorized as bft-2 or bft-3, we found in our collection two strains harboring bft-3, a variant that had been described 2000-01-01T00:00:00Z2000 Feb2025-04-05T10:13:58.748Z2019-03-27T00:18:21ZS-EPMC861571065535410.1128/JCM.38.2.607-612.2000