title: Long-range mapping of the Streptococcus agalactiae phylogenetic lineage restriction digest pattern type III-3 reveals clustering of virulence genes.
abstract: Human isolates of serotype III Streptococcus agalactiae (group B streptococcus [GBS]) can be divided into three separate phylogenetic lineages based on analysis of the restriction digest patterns (RDPs) of chromosomal DNA. Nine DNA sequences that are present in all isolates of the RDP III-3 phylogenetic lineage, but not in the other lineages, were identified by genomic subtractive hybridization. A complete physical map of a III-3 chromosome was constructed. Six of the nine III-3-specific sequences mapped to a 340-kb Sse8387I fragment which contains or is located close to known GBS virulence genes. One of the III-3-specific probes, AW-10, encodes part of GBSi1, a group II intron that is inserted at two sites within the GBS genome. The second chromosomal site for GBSi1 was isolated, sequenced, and mapped to a location near the locus responsible for hemolysin production. These findings suggest that the genetic variation that distinguishes the RDP type III-3 strains from other serotype III strains occurs largely within localized areas of the genome containing known or putative virulence genes.
authors.affiliation: Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA. john.bohnsack@hsc.utah.edu
authors.forename: John F
authors.initials: JF
authors.lastname: Bohnsack
authors.forename: April A
authors.initials: AA
authors.lastname: Whiting
authors.forename: Russell D
authors.initials: RD
authors.lastname: Bradford
authors.forename: Brenna K
authors.initials: BK
authors.lastname: Van Frank
authors.forename: Shinji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Elisabeth E
authors.initials: EE
authors.lastname: Adderson
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping / Q000379:methods; D015342:DNA Probes; D004269:DNA, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D015183:Restriction Mapping / Q000379:methods; D012703:Serotyping; D013292:Streptococcus agalactiae / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D014774:Virulence / Q000235:genetics
chemical_list: D015342:DNA Probes; D004269:DNA, Bacterial