The SEF14 fimbrial antigen of Salmonella enterica serovar Enteritidis is encoded within a pathogenicity islet

The DNA sequence of the chromosomal gene cluster encoding the SEF14 fimbria e of Salmonella enterica serovar Enteritidis was determined. Five contiguou s open reading frames, sefABCDE, were identified. The sefE gene shared sign ificant homology with araC-like positive regulators. Serovar-associated vir ulence plasmid (SAP) genes orf7,8,9 and pefI were identified immediately ad jacent to the sef operon. The pefI gene encoded a putative regulator of the Plasmid-encoded fimbrial antigen (PEF) expression. The entire sef-pef regi on, Ranked by two IS-like elements, was inserted adjacent to leuX that enco ded a transfer RNA molecule. The organisation of this region was suggestive of a classic pathogenicity islet. Southern hybridisation confirmed two cop ies of the SAP derived orf7,8,9 and pefI region in S. Enteritidis, one in t he chromosome and one on the SAP. Of other group D Salmonella, only S. Bleg dam and S. Moscow harboured both chromosomal and plasmid copies of pefI-orf 9 region although polymorphism was evident. Crown Copyright (C) 2001 Publis hed by Elsevier Science B.V. All rights reserved.