Evolution of the capsular operon of Streptococcus iniae in response to vaccination

Millard, Candice M., Baiano, Justice C. F., Chan, Candy, Yuen, Benedict, Aviles, Fabian, Landos, Matt, Chong, Roger S. M., Benedict, Suresh and Barnes, Andrew C. (2012) Evolution of the capsular operon of Streptococcus iniae in response to vaccination. Applied & Environmental Microbiology, 78 23: 8219-8226. doi:10.1128/AEM.02216-12

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Author Millard, Candice M.
Baiano, Justice C. F.
Chan, Candy
Yuen, Benedict
Aviles, Fabian
Landos, Matt
Chong, Roger S. M.
Benedict, Suresh
Barnes, Andrew C.
Total Author Count Override 9
Title Evolution of the capsular operon of Streptococcus iniae in response to vaccination
Journal name Applied & Environmental Microbiology   Check publisher's open access policy
ISSN 0099-2240
Publication date 2012-09
Sub-type Article (original research)
DOI 10.1128/AEM.02216-12
Open Access Status File (Publisher version)
Volume 78
Issue 23
Start page 8219
End page 8226
Total pages 8
Place of publication Washington, DC, United States
Publisher American Society for Microbiology
Collection year 2013
Language eng
Abstract Streptococcus iniae causes severe septicemia and meningitis in farmed fish and is also occasionally zoonotic. Vaccination against S. iniae is problematic, with frequent breakdown of protection in vaccinated fish. The major protective antigens in S. iniae are the polysaccharides of the capsule, which are essential for virulence. Capsular biosynthesis is driven and regulated by a 21-kb operon comprising up to 20 genes. In a long-term study, we have sequenced the capsular operon of strains that have been used in autogenous vaccines across Australia and compared it with the capsular operon sequences of strains subsequently isolated from infected vaccinated fish. Intriguingly, strains isolated from vaccinated fish that subsequently become infected have coding mutations that are confined to a limited number of genes in the cps operon, with the remainder of the genes in the operon remaining stable. Mutations in strains in diseased vaccinated fish occur in key genes in the capsular operon that are associated with polysaccharide configuration (cpsG) and with regulation of biosynthesis (cpsD and cpsE). This, along with high ratios of nonsynonymous to synonymous mutations within the cps genes, suggests that immune response directed predominantly against capsular polysaccharide may be driving evolution in a very specific set of genes in the operon. From these data, it may be possible to design a simple polyvalent vaccine with a greater operational life span than the current monovalent killed bacterins.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Supplemental material (read only) - http://aem.asm.org/content/78/23/8219/suppl/DCSupplemental. Published ahead of print: 21 September 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
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Created: Wed, 14 Nov 2012, 16:00:22 EST by Gail Walter on behalf of School of Biological Sciences