Regulation of capsule gene expression by group A Streptococcus during pharyngeal colonization and invasive infection

Citation
L. Gryllos et al., Regulation of capsule gene expression by group A Streptococcus during pharyngeal colonization and invasive infection, MOL MICROB, 42(1), 2001, pp. 61-74
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
42
Issue
1
Year of publication
2001
Pages
61 - 74
Database
ISI
SICI code
0950-382X(200110)42:1<61:ROCGEB>2.0.ZU;2-X
Abstract
Capsular polysaccharide production by group A Streptococcus (GAS) is contro lled by transcription of the has operon that encodes the enzymes uniquely r equired for synthesis of the hyaluronic acid polysaccharide. To investigate the regulation of capsule gene expression during infection, we developed a reporter strain of GAS in which the has operon promoter directed transcrip tion of green fluorescent protein (GFP). Gfp expression was triggered withi n minutes after introduction of the reporter strain into the peritoneal cav ity of mice, as evidenced by the recovery of highly fluorescent GAS from th e peritoneum 1 h after challenge. Capsule gene expression was also stimulat ed in the bloodstream of infected mice, as intensely fluorescent bacteria w ere observed in blood samples collected after either intraperitoneal or int ravenous challenge. Using a similar approach, we also observed rapid induct ion of capsule gene expression in bacteria inoculated into the pharynx of b aboons. Compared to the inoculum, increased green fluorescence was recorded in bacteria recovered from throat swabs collected 1 h after inoculation in all five animals studied. We conclude that introduction of GAS into the ph arynx or into deep tissues results in rapid induction of has operon express ion, a critical adaptive response that enhances GAS survival in the infecte d host.