Attaching Effacement oftheRabbit Enterocyte BrushBorder Is EncodedonaSingle 96.5-Kilobase-Pair

specifying resistance to chloramphenicol, tetracycline, andkanamycin; pLV502 (8 kbp) specifying ampicillin resistance; pLV503 (1.9 kbp) specifying streptomycinresistance; andpLV504(80kbp) with noresistance markers. This EPECattached to HEp-2cells to producelocalized clumpsofbacteria (localized adhesion) andattached intimately to the enterocyte surface, leading toloss of the brush border (attaching effacement). Plasmid pLV501 was also found to specify the ability toproduce localized adhesion on HEp-2cells and attaching effacement in a rabbit ileal explant model system.Restriction maps showed considerable dissimilarities between pLV501 and pMAR-2, an EPEC plasmidcarrying the EPEC adherence factor (EAF) genes. Furthermore, pLV501 did not hybridize with the EAFprobe, whereas pLV504did. There wassequence homology between pLV501and large plasmids in all sevenotherwell-characterized EPEC,onlyfive ofwhichhybridizedwiththeEAFprobe. ThesefindingsindicatethatpLV501carries atleast oneofthe genesresponsibleforproductionofthe brushborderdamagecharacteristicofEPEC.Escherichia coli produces gastroenteritis by at least five