A 65-Kilobase Pathogenicity Island Is Unique to Philadelphia-1 Strains of Legionella pneumophila

Abstract
Nucleotide sequence analysis of an ∼80-kb genomic region revealed an ∼65-kb locus that bears hallmarks of a pathogenicity island. This locus includes homologues of a type IV secretion system, mobile genetic elements, and known virulence factors. Comparative studies with other Legionella pneumophila strains and serogroups indicated that this ∼65-kb locus is unique to L . pneumophila serogroup 1 Philadelphia-1 strains.