Regulation of virulence gene expression

Thomas, Mark S.; Wigneshweraraj, Sivaramesh

doi:10.1080/21505594.2014.995573

Cited by 48 publications

(38 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Its versatility depends on its ability to sense and respond to environmental changes by modulating gene expression, using transcription factors (TFs) and regulatory small RNAs (sRNAs). The expression of S. aureus virulence factors is tightly controlled by multiple regulators, including TFs, two-component systems and sRNAs (4–6). Many of these regulators are therefore essential for infection (7).…”

Section: Introductionmentioning

confidence: 99%

Insights into the regulation of small RNA expression: SarA represses the expression of two sRNAs inStaphylococcus aureus

Mauro¹,

Rouillon²,

Felden³

2016

Nucleic Acids Res

View full text Add to dashboard Cite

The opportunistic pathogen Staphylococcus aureus expresses transcription factors (TFs) and regulatory small RNAs (sRNAs) which are essential for bacterial adaptation and infectivity. Until recently, the study of S. aureus sRNA gene expression regulation was under investigated, but it is now an expanding field. Here we address the regulation of Srn_3610_SprC sRNA, an attenuator of S. aureus virulence. We demonstrate that SarA TF represses srn_3610_sprC transcription. DNase I footprinting and deletion analyses show that the SarA binding site on srn_3610_sprC belongs to an essential 22 bp DNA region. Comparative analysis also revealed another possible site, this time in the srn_9340 promoter. SarA specifically binds these two sRNA promoters with high affinity in vitro and also represses their transcription in vivo. Chromatin immunoprecipitation (ChIP) assays confirmed SarA attachment to both promoters. ChIP and electrophoretic mobility shift assays targeting σA RNA polymerase subunit or using bacterial RNA polymerase holoenzyme suggested that SarA and the σA bind srn_3610_sprC and srn_9340 promoters in a mutually exclusive way. Beyond the mechanistic study of SarA repression of these two sRNAs, this work also suggests that some S. aureus sRNAs belong to the same regulon and act jointly in responding to environmental changes.

show abstract

Section: Introductionmentioning

confidence: 99%

Insights into the regulation of small RNA expression: SarA represses the expression of two sRNAs inStaphylococcus aureus

Mauro¹,

Rouillon²,

Felden³

2016

Nucleic Acids Res

View full text Add to dashboard Cite

show abstract

“…The pathogenicity of the bacteria depends on the expression of VGs, which has to be co-ordinated for invasion and disease to occur in the host. Very often, expression involves very complex cascades of component systems and quorum sensing (Thomas and Wigneshweraraj, 2014).…”

Section: Discussionmentioning

confidence: 99%

Studies on avian pathogenic Escherichia coli in commercial broiler chicken in South East Queensland

Awawdeh¹,

Turni²,

Henning³

et al.

View full text Add to dashboard Cite

Avian pathogenic Escherichia coli (APEC) is the causative agent of avian colibacillosis, a localised or systemic infection resulting in clinical diseases such as colisepticemia, chronic respiratory disease and swollen-head syndrome. Globally, avian colibacillosis is the leading cause of morbidity and mortality in poultry, and it has been associated with massive economic losses and welfare problems.This organism is of public health significance as APEC is communicable to humans. The diagnosis of avian colibacillosis relies on clinical signs, typical pathological lesions and culture of E. coli from affected tissue(s). Antimicrobial therapy is often used both for treatment and control. Previous overseas studies have characterised APEC and identified virulence genes (VGs) that can be used as molecular markers for the identification of APEC. Little is known about APEC in broiler chickens in Australia.The aim of this thesis was to gain a better understanding of the epidemiology of APEC in Australian broiler flocks and how factors including presence of VGs and phylogenetic group can improve the identification of this pathotype in Australia. Firstly, three faecal DNA extraction methods were evaluated. Faeces were collected from healthy chickens and chickens with colibacillosis from commercial broiler farms in South East Queensland (SEQ). The extracted DNA was screened by a pentaplex-PCR for five APEC-associated VGs (iroN, iutA, iss, hlyF and ompT). DNA extracted from E. coli isolates cultured from the cloaca and organs of the birds were screened using the same PCR.Repeated bead beating plus column elution was the preferred DNA extraction method, as it yielded good PCR quality and adequate quantity DNA. However, identifying APEC by direct detection of the five VGs from the faecal material was not feasible as all of these genes were also detected in all of the birds. However, the VGs were more commonly detected in E. coli isolates cultured from birds with colibacillosis.A cross-sectional study was performed to estimate APEC farm-level prevalence in healthy broiler chickens in SEQ and to identify potential risk factors associated with the carriage of APEC. At the farm-level, all of the 40 farms sampled were positive for APEC, that is at least one bird per farm carried APEC, while the within-farm prevalence was 63% (95% Confidence Interval: 55.8, 70.2).Higher APEC within-farm bird-level prevalence was significantly associated with the usage of well water as a source of drinking water, failure to disinfect the water line after each flock, farm visitors not showering before entering the shed, distances greater than 20 metres between the car park and the poultry shed and the presence of wild birds within 50 metres of the shed. Chlorinating the drinking water combined with automatic water filtration reduced within-farm bird-level APEC prevalence. Page | 3Therefore, based on the results concluded from the multivariable model, improving biosecurity and water treatments might reduce APEC prevalence, decrease the risk of co...

show abstract

“…In-vitro studies have reported that probiotic strains obtained from commercially available fermented foods are capable of inhibiting pathogenic micro-organisms due to production of acids, hydrogen peroxide, bacteriocins and other antimicrobials (Guerrero et al, 2013;Denkova et al, 2013). Every micro-organism produces virulence factors to invade the mucosa or tissues which may be adherence (pili), invasion factors (surface components encoded on plasmid or chromosome), capsules (lipopolysaccharides) and toxins (endotoxins and exotoxins) (Thomas and Wigneshweraraj, 2014). These virulence factors are genetically encoded for example, enterotoxins produced by Vibrio cholera, Staphylococcus aureus and Escherichia coli are encoded on chromosomes, anthrax toxins produced by Bacillus anthracis are encoded on plasmid and shiga toxins produced by Escherichia coli are encoded on bacteriophage (Peterson, 1996).…”

Section: Mechanism Of Actionmentioning

confidence: 99%

Probiotics from food and eubiosis in Gut: a commensalism

Sucheta

Gehlot

Arora

2018

AJDFR

View full text Add to dashboard Cite

Micro-organisms are not only pathogenic but also commensal to humans and are associated with many tissues. They show commensalism by excluding or inhibiting pathogens in intestine lumen or they can improve gut barrier by inducing mucin secretion, defensin production and enhancing tight junctions stability. They can also improve immune system modulation. This may be due to activation of certain signaling pathways by probiotic bacteria which enhance adaptive immunity. Advances on the knowledge of inter-relationships between strain specificity, molecular basis of mechanism of action, host cell factors including its genetic makeup can help to determine potential benefits derived from intake of probiotic food supplements.

show abstract

Regulation of virulence gene expression

Cited by 48 publications

References 27 publications

Insights into the regulation of small RNA expression: SarA represses the expression of two sRNAs inStaphylococcus aureus

Insights into the regulation of small RNA expression: SarA represses the expression of two sRNAs inStaphylococcus aureus

Studies on avian pathogenic Escherichia coli in commercial broiler chicken in South East Queensland

Probiotics from food and eubiosis in Gut: a commensalism

Contact Info

Product

Resources

About