Whole-Genome Sequences of Two Salmonella enterica Serovar Dublin Strains That Harbor the
 viaA
 ,
 viaB
 , and
 ompB
 Loci of the Vi Antigen

Mohammed, Manal; Vignaud, Marie-Léone; Cadel-Six, Sabrina

doi:10.1128/mra.00028-19

“…Paratyphi C, which also causes enteric fever, and some isolates of S . Dublin, which causes an enteric fever-like disease in humans with high fever and bacteremia but little gastrointestinal disease [ 53 – 55 ]. Interestingly, Vi capsule expression is not constrained to Salmonella spp.…”

Section: Resultsmentioning

confidence: 99%

“…Other Salmonella enterica serovars have acquired the viaB locus and express Vi capsule. These include the human-specific pathogen S. Paratyphi C, which also causes enteric fever, and some isolates of S. Dublin, which causes an enteric fever-like disease in humans with high fever and bacteremia but little gastrointestinal disease [53][54][55]. Interestingly, Vi capsule expression is not constrained to Salmonella spp.…”

Section: Conservation Of the Fouru Rnat In VI Capsule-producing Entementioning

confidence: 99%

A Salmonella Typhi RNA thermosensor regulates virulence factors and innate immune evasion in response to host temperature

Brewer

¹

,

Twittenhoff

²

,

Kortmann³

et al. 2021

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Sensing and responding to environmental signals is critical for bacterial pathogens to successfully infect and persist within hosts. Many bacterial pathogens sense temperature as an indication they have entered a new host and must alter their virulence factor expression to evade immune detection. Using secondary structure prediction, we identified an RNA thermosensor (RNAT) in the 5’ untranslated region (UTR) of tviA encoded by the typhoid fever-causing bacterium Salmonella enterica serovar Typhi (S. Typhi). Importantly, tviA is a transcriptional regulator of the critical virulence factors Vi capsule, flagellin, and type III secretion system-1 expression. By introducing point mutations to alter the mRNA secondary structure, we demonstrate that the 5’ UTR of tviA contains a functional RNAT using in vitro expression, structure probing, and ribosome binding methods. Mutational inhibition of the RNAT in S. Typhi causes aberrant virulence factor expression, leading to enhanced innate immune responses during infection. In conclusion, we show that S. Typhi regulates virulence factor expression through an RNAT in the 5’ UTR of tviA. Our findings demonstrate that limiting inflammation through RNAT-dependent regulation in response to host body temperature is important for S. Typhi’s “stealthy” pathogenesis.

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“…It is estimated that over 680,000 humans throughout the world are killed each year by iNTS. The most predominant iNTS serovars are Typhimurium, Enteritidis and Dublin (14,15). It is therefore very crucial to use accurate, reliable and highly discriminative subtyping methods for epidemiological surveillance and outbreak investigation.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of WGS-subtyping methods for epidemiological surveillance of foodborne salmonellosis.

Mohammed

¹

,

Thapa

²

2020

Preprint

Self Cite

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Background: Salmonellosis is one of the most common foodborne diseases worldwide. Although human infection by non-typhoidal Salmonella (NTS) enterica subspecies enterica is associated primarily with a self-limiting diarrhoeal illness, invasive bacterial infections (such as septicaemia, bacteraemia and meningitis) were also reported. Human outbreaks of NTS were reported in several countries all over the world including developing as well as high-income countries. Conventional laboratory methods such as pulsed field gel electrophoresis (PFGE) do not display adequate discrimination and have their limitations in epidemiological surveillance. It is therefore very crucial to use accurate, reliable and highly discriminative subtyping methods for epidemiological characterisation and outbreak investigation. Methods: Here, we used different whole genome sequence (WGS)-based subtyping methods for retrospective investigation of two different outbreaks of Salmonella Typhimurium and Salmonella Dublin that occurred in 2013 in UK and Ireland respectively. Results: Single nucleotide polymorphism (SNP)-based cluster analysis of Salmonella Typhimurium genomes revealed well supported clades, that were concordant with epidemiologically defined outbreak and confirmed the source of outbreak is due to consumption of contaminated mayonnaise. SNP-analyses of Salmonella Dublin genomes confirmed the outbreak however the source of infection could not be determined. The core genome multilocus sequence typing (cgMLST) was discriminatory and separated the outbreak strains of Salmonella Dublin from the non-outbreak strains that were concordant with the epidemiological data however cgMLST could neither discriminate between the outbreak and non-outbreak strains of Salmonella Typhimurium nor confirm that contaminated mayonnaise is the source of infection, On the other hand, other WGS-based subtyping methods including multilocus sequence typing (MLST), ribosomal MLST (rMLST), whole genome MLST (wgMLST), clustered regularly interspaced short palindromic repeats (CRISPRs), prophage sequence profiling, antibiotic resistance profile and plasmid typing methods were less discriminatory and could not confirm the source of the outbreak. Conclusions: Foodborne salmonellosis is an important concern for public health therefore, it is crucial to use accurate, reliable and highly discriminative subtyping methods for epidemiological surveillance and outbreak investigation. In this study, we showed that SNP-based analyses do not only have the ability to confirm the occurrence of the outbreak but also to provide definitive evidence of the source of the outbreak in real-time.

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“…Salmonellosis is one of the most common foodborne diseases worldwide and has been associated with high morbidity and mortality rates. It is estimated that over [13,14]. It is therefore very crucial to use accurate, reliable and highly discriminative subtyping methods for epidemiological surveillance and outbreak investigation.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of WGS-subtyping methods for epidemiological surveillance of foodborne salmonellosis

Mohammed

¹

,

Thapa

²

2020

Self Cite

View full text Add to dashboard Cite

Background: Salmonellosis is one of the most common foodborne diseases worldwide. Although human infection by non-typhoidal Salmonella (NTS) enterica subspecies enterica is associated primarily with a self-limiting diarrhoeal illness, invasive bacterial infections (such as septicaemia, bacteraemia and meningitis) were also reported. Human outbreaks of NTS were reported in several countries all over the world including developing as well as high-income countries. Conventional laboratory methods such as pulsed field gel electrophoresis (PFGE) do not display adequate discrimination and have their limitations in epidemiological surveillance. It is therefore very crucial to use accurate, reliable and highly discriminative subtyping methods for epidemiological characterisation and outbreak investigation. Methods: Here, we used different whole genome sequence (WGS)-based subtyping methods for retrospective investigation of two different outbreaks of Salmonella Typhimurium and Salmonella Dublin that occurred in 2013 in UK and Ireland respectively. Results: Single nucleotide polymorphism (SNP)-based cluster analysis of Salmonella Typhimurium genomes revealed well supported clades, that were concordant with epidemiologically defined outbreak and confirmed the source of outbreak is due to consumption of contaminated mayonnaise. SNP-analyses of Salmonella Dublin genomes confirmed the outbreak however the source of infection could not be determined. The core genome multilocus sequence typing (cgMLST) was discriminatory and separated the outbreak strains of Salmonella Dublin from the non-outbreak strains that were concordant with the epidemiological data however cgMLST could neither discriminate between the outbreak and non-outbreak strains of Salmonella Typhimurium nor confirm that contaminated mayonnaise is the source of infection, On the other hand, other WGS-based subtyping methods including multilocus sequence typing (MLST), ribosomal MLST (rMLST), whole genome MLST (wgMLST), clustered regularly interspaced short palindromic repeats (CRISPRs), prophage sequence profiling, antibiotic resistance profile and plasmid typing methods were less discriminatory and could not confirm the source of the outbreak. Conclusions: Foodborne salmonellosis is an important concern for public health therefore, it is crucial to use accurate, reliable and highly discriminative subtyping methods for epidemiological surveillance and outbreak investigation. In this study, we showed that SNP-based analyses do not only have the ability to confirm the occurrence of the outbreak but also to provide definitive evidence of the source of the outbreak in real-time.

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Whole-Genome Sequences of Two Salmonella enterica Serovar Dublin Strains That Harbor the viaA , viaB , and ompB Loci of the Vi Antigen

Cited by 6 publications

References 17 publications

A Salmonella Typhi RNA thermosensor regulates virulence factors and innate immune evasion in response to host temperature

A Salmonella Typhi RNA thermosensor regulates virulence factors and innate immune evasion in response to host temperature

Evaluation of WGS-subtyping methods for epidemiological surveillance of foodborne salmonellosis.

Evaluation of WGS-subtyping methods for epidemiological surveillance of foodborne salmonellosis

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