An emm-type specific qPCR to track bacterial load during experimental human Streptococcus pyogenes pharyngitis

Fabri, Loraine; Azzopardi, Kristy; Osowicki, Joshua; Frost, Hannah R.; Smeesters, Pierre; Steer, Andrew C.

doi:10.1186/s12879-021-06173-w

Cited by 4 publications

(3 citation statements)

References 37 publications

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“…All participants were treated with antibiotics, either at the time of diagnosis (P+) or ~120 h after challenge in those without pharyngitis. Pharyngeal colonisation by the challenge strain was measured by quantitative PCR 19 , and a cycle threshold (CT)-value >35 was classified as no pharyngeal colonisation with S. pyogenes. All 19 P+ participants reported CT-values indicative of pharyngeal colonisation (median 21.24 at the timepoint of pharyngitis diagnosis, IQR 20.61-22.64) while only one P− participant exhibited a CT-value of <35 at any timepoint 17 .…”

Section: Resultsmentioning

confidence: 99%

Immune signature of acute pharyngitis in a Streptococcus pyogenes human challenge trial

et al. 2022

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Streptococcus pyogenes causes at least 750 million infections and more than 500,000 deaths each year. No vaccine is currently available for S. pyogenes and the use of human challenge models offer unique and exciting opportunities to interrogate the immune response to infectious diseases. Here, we use high-dimensional flow cytometric analysis and multiplex cytokine and chemokine assays to study serial blood and saliva samples collected during the early immune response in human participants following challenge with S. pyogenes. We find an immune signature of experimental human pharyngitis characterised by: 1) elevation of serum IL-1Ra, IL-6, IFN-γ, IP-10 and IL-18; 2) increases in peripheral blood innate dendritic cell and monocyte populations; 3) reduced circulation of B cells and CD4+ T cell subsets (Th1, Th17, Treg, TFH) during the acute phase; and 4) activation of unconventional T cell subsets, γδTCR + Vδ2+ T cells and MAIT cells. These findings demonstrate that S. pyogenes infection generates a robust early immune response, which may be important for host protection. Together, these data will help advance research to establish correlates of immune protection and focus the evaluation of vaccines.

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Section: Resultsmentioning

confidence: 99%

Immune signature of acute pharyngitis in a Streptococcus pyogenes human challenge trial

et al. 2022

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“…Considering all available data, one participant (SN057) who was not contemporaneously diagnosed with pharyngitis 35 clearly did have pharyngitis and they have been categorised as such in this study. All participants with pharyngitis had S. pyogenes detected by throat swab qPCR and culture at multiple timepoints 61 . S. pyogenes colonisation was detected in only one of the 6 participants (participant SN013) who did not develop pharyngitis 35 .…”

Section: Experimental Pharyngitis Modelmentioning

confidence: 99%

Streptococcus pyogenespharyngitis elicits diverse antibody responses to key vaccine antigens influenced by the imprint of past infections

Osowicki,

Frost,

Azzopardi

et al. 2024

Preprint

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Knowledge gaps regarding human immunity toStreptococcus pyogeneshave impeded vaccine development. To address these gaps and evaluate vaccine candidates, we established a human challenge model ofS. pyogenespharyngitis. Here, we analysed antibody responses in serum and saliva against 19 antigens to identify characteristics distinguishing 19 participants who developed pharyngitis and 6 who did not. Pharyngitis elicited serum IgG responses to key vaccine antigens and a muted mucosal IgA response, whereas the 6 participants without pharyngitis had more pronounced IgA responses and minimal IgG responses. Serum IgG responses to pharyngitis in adult participants resembled those observed in children and were inversely correlated with the magnitude of pre-existing responses. While a straightforward correlate of protection was not evident, baseline antibody signatures distinguished clinical and immunological outcomes following experimental challenge. This highlights the influence of a complex humoral imprint from previous exposure, relevant for interpreting immunogenicity in forthcoming vaccine trials.

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“…For the most part, PCR is used qualitatively, presence or absence. However, disease diagnosis can be further explored through the application of quantitative PCR, which can give information about the load of the infectious agent ( Bhullar et al, 2014 ; Abdullah et al, 2018 ; Fabri et al, 2021 ). This technique can be particularly useful where normal flora is associated with the etiology of disease, for example, bovine respiratory disease (BRD) ( Pansri et al, 2020 ; Klompmaker et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Meta-Analysis of qPCR for Bovine Respiratory Disease Based on MIQE Guidelines

Marsh

Quinn

2022

Front. Mol. Biosci.

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Qualitative and quantitative PCR-based tests are widely used in both diagnostics and research to assess the prevalence of disease-causing pathogens in veterinary medicine. The efficacy of these tests, usually measured in terms of sensitivity and specificity, is critical in confirming or excluding a clinical diagnosis. We undertook a meta-analysis to assess the inherent value of published PCR diagnostic approaches used to confirm and quantify bacteria and viruses associated with bovine respiratory disease (BRD) in cattle. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A thorough search of nine electronic databases (Web of Science, EBSCOhost, Cambridge journals online, ProQuest, PubMed, Sage journals online, ScienceDirect, Wiley online library and MEDLINE) was undertaken to find studies that had reported on the use of PCR and/or qPCR for the detection and/or quantification of BRD associated organisms. All studies meeting the inclusion criteria for reporting quantitative PCR for identification of BRD associated microorganisms were included in the analysis. Studies were then assessed on the applications of the Minimum Information for Publication of Quantitative Real-Time PCR Experiment (MIQE) and PCR primer/probe sequences were extracted and tested for in silico specificity using a high level of stringency. Fourteen full-text articles were included in this study. Of these, 79% of the analysed articles did not report the application of the MIQE guidelines in their study. High stringency in silico testing of 144 previously published PCR primer/probe sequences found many to have questionable specificity. This review identified a high occurrence of primer/probe sequences with a variable in silico specificity such that this may have implications for the accuracy of reporting. Although this analysis was only applied to one specific disease state, identification of animals suspected to be suffering from bovine respiratory disease, there appears to be more broadly a need for veterinary diagnostic studies to adopt international best practice for reporting of quantitative PCR diagnostic data to be both accurate and comparable between studies and methodologies.

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An emm-type specific qPCR to track bacterial load during experimental human Streptococcus pyogenes pharyngitis

Cited by 4 publications

References 37 publications

Immune signature of acute pharyngitis in a Streptococcus pyogenes human challenge trial

Immune signature of acute pharyngitis in a Streptococcus pyogenes human challenge trial

Streptococcus pyogenespharyngitis elicits diverse antibody responses to key vaccine antigens influenced by the imprint of past infections

Meta-Analysis of qPCR for Bovine Respiratory Disease Based on MIQE Guidelines

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