title: ISSa4-based differentiation of Streptococcus agalactiae strains and identification of multiple target sites for ISSa4 insertions.
abstract: A collection of 113 epidemiologically unrelated Streptococcus agalactiae strains were studied (group B streptococcus; GBS): they belonged to different serotypes and were isolated from pregnant women in China and Russia. The insertion sequence ISSa4 was found in 21 of 113 strains (18,6%). All of the strains with ISSa4 belonged to serotypes II and II/c and were characterized by the presence of IS1381 and IS861 as well as the absence of IS1548 and GBSi1. All of the strains with ISSa4 possessed both bca and bac virulence genes coding for alpha and beta antigens, respectively. Among 21 ISSa4-positive strains, 13 different HindIII patterns (D1 to D13) hybridizing with an ISSa4 probe were found. One of them (D13) contained a single HindIII hybridization fragment 6.5 kb in size that was found to be specific for all ISSa4-positive GBS strains. Multiple target sites for insertions of ISSa4 were identified and included a putative pathogenicity island, "housekeeping" genes, and intergenic regions, as well as the genes for hypothetical proteins. No significant similarity was observed in the sequences of the target genes for ISSa4 insertions, in the relative location of the target genes on the chromosome, or the biological functions of the encoded proteins. The possible significance of ISSa4-based differentiation of the strains and the presence of possible "hot spots" for insertions of ISSa4 in GBS genome are discussed.
authors.affiliation: Institute of Experimental Medicine, Academy of Medical Sciences, Saint Petersburg 197376, Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Dmitriev
authors.forename: Adong
authors.initials: A
authors.lastname: Shen
authors.forename: Xuzhuang
authors.initials: X
authors.lastname: Shen
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Yang
mesh_terms: D001483:Base Sequence; D004251:DNA Transposable Elements; D005260:Female; D018628:Gene Dosage; D006801:Humans; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D011247:Pregnancy; D012703:Serotyping; D013292:Streptococcus agalactiae / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements