Diversity of LPS-dependent Salmonella phages
Salmonella enterica subsp. enterica consists of more than 2400 serotypes as determined by their antigenic response to specific sera. O-antigen (O-Ag) attached to the conserved core sugars of lipopolysaccharide (LPS) is one of the major contributors of diversity. To tackle this vast surface diversity, Salmonella phages target either conserved or serotype specific receptors. While repeating units of O-Ag may either act as receptors or mask conserved core sugars, outer membrane proteins are in most cases readily accessible for phage adsorption.
In order to establish a diverse Salmonella phage collection, we isolated 42 phages from the environment using ten prevalent Salmonella serotypes. By using defined knockout mutants of prophage cured S. Typhimurium LT2, we showed that nine phages were dependent on the outer membrane B12 vitamin transporter, BtuB. Another 30 phages isolated on serotypes Enteritidis, Typhimurium and Dublin were dependent on O-Ag for infection. Furthermore, use of a strain that lacks O-Ag, allowed isolation of three phages that were blocked by the O-Ag, but nevertheless infected other serotypes, suggesting that the receptor may be core sugars masked by the LT2 O-Ag.
Host range analysis on 71 prevalent serotypes showed that BtuB-dependent phages have the broadest host range, suggesting conserved phage binding domains in BtuB across serotypes. While most O-Ag-dependent phages showed narrow host ranges, three phages demonstrated significantly broader host range. Interestingly, these three phages infect many strains including serotypes with similar O-Ag structures, suggesting that they absorb to common antigenic features of O-Ag.
Analysis of phage genome sequences will identify the strategies that the LPS-dependent phages can use to target specific receptors. Also genomic comparisons will allow us to determine host specific determinants of O-Ag dependent phages. In conclusion, both LPS and BtuB-dependent Salmonella phages are prevalent in the environment and LPS-dependent phages represent a highly diverse phage group.
In order to establish a diverse Salmonella phage collection, we isolated 42 phages from the environment using ten prevalent Salmonella serotypes. By using defined knockout mutants of prophage cured S. Typhimurium LT2, we showed that nine phages were dependent on the outer membrane B12 vitamin transporter, BtuB. Another 30 phages isolated on serotypes Enteritidis, Typhimurium and Dublin were dependent on O-Ag for infection. Furthermore, use of a strain that lacks O-Ag, allowed isolation of three phages that were blocked by the O-Ag, but nevertheless infected other serotypes, suggesting that the receptor may be core sugars masked by the LT2 O-Ag.
Host range analysis on 71 prevalent serotypes showed that BtuB-dependent phages have the broadest host range, suggesting conserved phage binding domains in BtuB across serotypes. While most O-Ag-dependent phages showed narrow host ranges, three phages demonstrated significantly broader host range. Interestingly, these three phages infect many strains including serotypes with similar O-Ag structures, suggesting that they absorb to common antigenic features of O-Ag.
Analysis of phage genome sequences will identify the strategies that the LPS-dependent phages can use to target specific receptors. Also genomic comparisons will allow us to determine host specific determinants of O-Ag dependent phages. In conclusion, both LPS and BtuB-dependent Salmonella phages are prevalent in the environment and LPS-dependent phages represent a highly diverse phage group.
Reference:
Posters Day 2-T03-Pos-25
Session:
Posters Covering Ecology, Host population control, Co-Evolutionary dynamics and Subversion/Evasion of Host Defences
Presenters:
Y. Emre Gencay
Session:
Day 2 Posters Covering: Ecology, Host population control, Co-evolutionary dynamics and Subversion/Evasion of host defences
Presentation type:
Poster presentation
Room:
Poster Halls
Date:
Tuesday, 19 July 2016
Time:
12:05 - 15:00