Identification and molecular characterisation of a fibrinogen binding protein from Streptococcus iniae

Baiano, Justice C. F., Tumbol, Reiny A., Umapathy, Aarti and Barnes, Andrew C. (2008) Identification and molecular characterisation of a fibrinogen binding protein from Streptococcus iniae. BMC Microbiology, 8 Article Number: 67. doi:10.1186/1471-2180-8-67


Author Baiano, Justice C. F.
Tumbol, Reiny A.
Umapathy, Aarti
Barnes, Andrew C.
Title Identification and molecular characterisation of a fibrinogen binding protein from Streptococcus iniae
Formatted title
 Identification and molecular characterisation of a fibrinogen binding protein from Streptococcus iniae
Journal name BMC Microbiology   Check publisher's open access policy
ISSN 1471-2180
Publication date 2008-04-23
Year available 2008
Sub-type Article (original research)
DOI 10.1186/1471-2180-8-67
Open Access Status DOI
Volume 8
Start page Article Number: 67
Total pages 16
Editor M. Norton
Place of publication London, England
Publisher BioMed Central Ltd.
Language eng
Subject C1
860901 Veterinary Biological Preventatives (e.g. Vaccines)
060501 Bacteriology
070707 Veterinary Microbiology (excl. Virology)
070404 Fish Pests and Diseases
0707 Veterinary Sciences
Abstract Background: Binding of serum components by surface M-related proteins, encoded by the emm genes, in streptococci constitutes a major virulence factor in this important group of organisms. The present study demonstrates fibrinogen binding by S. iniae, a Lancefield non-typeable pathogen causing devastating fish losses in the aquaculture industry and an opportunistic pathogen of humans, and identifies the proteins involved and their encoding genes.
Formatted abstract
Background
Binding of serum components by surface M-related proteins, encoded by the emm genes, in streptococci constitutes a major virulence factor in this important group of organisms. The present study demonstrates fibrinogen binding by S. iniae, a Lancefield non-typeable pathogen causing devastating fish losses in the aquaculture industry and an opportunistic pathogen of humans, and identifies the proteins involved and their encoding genes.
Results
Fibrinogen binding by S. iniae significantly reduced respiratory burst activity of barramundi peritoneal macrophages in primary cultures compared to BSA-treated or untreated controls, indicating a potentially important role for fibrinogen binding cell-surface proteins in avoiding phagocytic attack in fish. We describe a novel emm-like gene, simA, encoding a 57 kDa fibrinogen binding M-like protein in S. iniae. These SiM proteins and their corresponding tetrameric structures from some sequevar types (~230 kDa) bound fibrinogen in Western blots. simA was most closely related (32% identity) to the demA gene of S. dysgalactiae. Genome walking and sequencing determined the genetic organization of the simA region had similarities to the mgrC regulon in GCS and to S. uberis. Moreover, a putative multigene regulator, mgx was orientated in the opposite direction to the simA gene in common with S. uberis, but contrary to findings in GAS and GCS. In GAS, diversity among emm-genes and consequent diversity of their M-related proteins results in substantial antigenic variation. However, an extensive survey of S. iniae isolates from diverse geographic regions and hosts revealed only three variants of the gene, with one sequevar accounting for all but two of the 50 isolates analysed.
Conclusion
These proteins play a role in avoiding oxidative attack by phagocytic cells during infection of fish by S. iniae, but genetic diversity amongst these key surface proteins has not yet arisen. This lack of diversity coupled with a functional role in macrophage resistance suggests that these proteins may constitute important targets for future vaccines against S. iniae in fish.
Keyword Group-a Streptococcus
Equi Subsp Equi
Complete Genome Sequence
Rheumatic Heart-disease
Group-C
Pyogenes
Virulence
strain
fish
Pathogen
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2009 Higher Education Research Data Collection
Centre for Marine Studies Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 16 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 18 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Wed, 15 Apr 2009, 01:05:07 EST by Peter Fogarty on behalf of Centre for Marine Studies