Impact of Bacterial Expression and Immune Response in the Severity of Pertussis

Study Overview
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Brief Summary
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The resurgence of pertussis is associated with an evolutionary mechanism under the pressure of current acellular vaccines, with a possible impact on vaccine effectiveness and disease expression. Little is known about the mechanisms involved in the clinical variability of pertussis, including its most severe malignant form observed in infants (mortality between 50-80%). The main challenges are: (i) the lack of knowledge about the gene expression of B. pertussis strains currently circulating during human infection, incorporating evolutionary changes and vaccine-induced selective pressure; (ii) the poor understanding of the variability in clinical expression of pertussis, and (iii) the lack of biomarkers to predict disease severity or prognosis in infants. An integrative strategy combining a clinical, microbiological, immunological and 'omic' approach from a prospective cohort of children with pertussis will be used to identify 'in situ' expression profiles of B. pertussis genes and proteins incorporating recent evolutionary changes and a systemic and respiratory immune signature in B. pertussis-infected children according to severity. Results should furthermore serve as a prerequisite for the identification of severity biomarkers and new vaccine antigen candidates taking into account specific immune responses in infants.

Detailed Description
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The study design is characterized by 4 work packages: Collection of clinical data and biological samples (deep nasal swab, blood sample) from children with pertussis Construction and validation of a microbial panel of 200 genes of interest (involved in virulence and/or potential vaccine antigens) for transcriptomic analysis Transcriptomic study using the panel of interest of B. pertussis isolates from nasopharyngeal swabs preserved with an RNA stabilizer, using the Nanostring® technique Study of the immune response during pertussis

Official Title
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Impact of Bacterial Expression and Immune Response in the Severity of Pertussis

Conditions
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Bordetella Pertussis, Whooping Cough

Intervention / Treatment
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* Biological: Nasopharyngeal swab
* Biological: Blood samples


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: be between the ages of 0 and 15 years inclusive be suspected of having pertussis by the physician in charge, with the prescription of a diagnostic PCR (pertussis PCR, which may be a syndromic PCR, a PCR targeting IS481 and/or IS1001) be free of any pathology/treatment that may influence the immune response (autoimmune/inflammatory pathology or immune deficiency not listed above, hepatic insufficiency, taking immunosuppressive treatment (including taking oral corticosteroids with a dose ≥ 10 mg/d Prednisone equivalent for more than 15 days) Have received age-appropriate information and written assent or consent from their parents/legal guardians be affiliated with or benefiting from a social security plan Exclusion Criteria: Patient with any pathology/treatment that may influence the immune response (autoimmune/inflammatory pathology or immune deficiency not listed above, hepatic failure, taking immunosuppressive therapy (including oral corticosteroids with dose ≥ 10 mg/d prednisone equivalent for more than 15 days) Use of antibiotics active against pertussis in the 24 hours preceding the sampling Delay between the result of the diagnostic sample (pertussis PCR) and the day of inclusion > 48 hours Patient's condition that, in the opinion of the physician, is incompatible with the expanded/additional sampling(s) required by the study Infant with a weight < 2.5 kg at the time of inclusion.

Ages Eligible for Study
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Maximum Age: 15 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Children between 0 and 15 years with suspected pertussis<br> | Biological: Nasopharyngeal swab<br>* For hospitalized patients : Nasopharyngeal swab (1 aspiration or 2 swabs (1 in each nostril)) For ambulatory patients : Deep nasal swab: 2 swabs (1 in each nostril), or 1 swab only for children for whom taking 2 swabs is complicated.<br>Biological: Blood samples<br>* For hospitalized patients : 3 to 7.5 ml For ambulatory patients: Fingertip blood sampling<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Measurement of expression level of Bp genes during infection by Nanostring transcriptomic analysis of Bp isolates from the nasopharynx of children with pertussis. | To identify in a standardized way the microbial in situ expression profiles of currently circulating Bp genes during infection in children ; | 3 years | 
| Measurement of plasma cytokine and chemokine concentrations by SIMOA digital ELISA | To determine systemic and respiratory immune responses in children during pertussis. | 3 years | 
| Phenotyping of immune cells by cytometry with a 20-color flow cytometry panel | To determine systemic and respiratory immune responses in children during pertussis. | 3 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Measurement of expression level of Bp genes which is modified by recent gene developments related to vaccine pressure by Nanostring transcriptomic analysis of Bp isolates | List of microbial genes which expression is modified by recent genomic developments related to vaccine pressure | 3 years | 
| Measurement of high expression level of Bp genes in all clinical forms of pertussis by Nanostring transcriptomic analysis of Bp isolates | To identify new candidate Bp genes for a future protein vaccine | 3 years | 
| Measurement of expression level of Bp genes which is associated with severe pertussis by Nanostring transcriptomic analysis of Bp isolates | List of virulence genes differentially expressed during severe pertussis | 3 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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vaccination