Résilience - COVID-19 - Résilience - Coronavirus disease 2019

Comparative study of the mucosal and systemic antibody responses against SARS-Cov2 – MUCOSA

Comparative study of the mucosal and systemic antibody responses against SARS-Cov2

Little is known about the relationship between the nasal mucosal antibody response and the systemic response during SARS-CoV2 infection. In particular: what is the respective role of the local and systemic response in the protection against the disease? Based on a cohort of 1900 Institut Curie employees, followed by 4 sampling points over time, we will assess the mucosal immune response in relation to the systemic immune response and clinical variables.

Assessment of the mucosal immune response in relation to the systemic immune response and clinical variables.

Although the COVID-19 pandemic peaked in March/April 2020 in France, the prevalence of infection is partially known as well as serological and local antibody response over time. We launched a study, called CURIOSA (NCT04369066), to collect and biobank sera from a large active and healthy population in Paris conurbation. A first intermediary serological analysis was carried out on 1847 sera samples to study anti-N- and anti-S- IgGs levels and their neutralizing capacities. High throughput methods for assessing IgM or IgA responses, not ready at the time of the study, are now ready to be tested. Furthermore, we started collecting nasopharyngeal swabs to further analyse the local antibody response.<br />The present MUCOSA project proposes to compare the systemic and nasopharyngeal presence of antibodies directed against the SARS-CoV-2 virus over time in the CURIOSA cohort. The project will quantify the prevalence of mucosal responses as compared to systemic ones and will enables to detect new asymptomatic or symptomatic re-infections during the current protracted second phase.

- Sampling in the CURIOSA protocol. On the day of inclusion, the volunteer has been registered in the laboratory management system of the Department of Biology and Theranostic Medicine at Institut Curie with the assignment of a unique number specifically for the study, allowing pseudonymization and serving as a key to consolidate biological and clinical data in the form of auto-questionnaires. The blood samples are taken at 4 times: T0 (day of inclusion), 1-3 months, 6 months, and 12 months’ post-inclusion. The nasopharyngeal swabs will be performed at 3 times: 1-3 months and 6 months’ post-inclusion for Institut Curie staff according to the criteria seen above In case of infection between sampling times, if the volunteer meets one of the four criteria above, a nasopharyngeal swab will be performed during the following visits.
- Preparation and storage of samples. After centrifugation of the blood sample, the serum is isolated, prepared, aliquoted and biobanked in the Clinical Immunology laboratory of the Institut Curie. Samples are sent frozen to the Institut Pasteur for further analysis. The Innate Immunity Unit (Institut Pasteur / Inserm U1223) has established protocols for extracting nasopharyngeal samples yielding material suitable for analyses of cytokines, antibodies as well as nasal microbial communities. The storage will be done in the clinical immunology laboratory which participates in the CRB of the Curie Institute in accordance with standard NF S 96-900.
- Data Management. The registration of volunteers and the collection of clinical data is organized by the investigation unit at the Research Department of the Hospital Ensemble of Institut Curie. The unique laboratory management system registration number is the volunteer registration number in the e-CRF. The pseudonymized study data: eligibility criteria, schedule of samples, clinical data will be collected in an e-CRF in the Ennov Clinical tool and will be managed by the Data Management unit of the Biometrics pole of the DREH (creation of the e-CRF and the database, quality, completeness and consistency of data, basic freezing, extraction, data retention).
- Assays for antibody detection and neutralization assay. The sera and the nasopharyngeal samples will be tested using the S-Flow approach (O Schwartz; Institut Pasteur) to characterize sera and nasopharyngeal samples for SARS-CoV-2-specific IgA and IgG. The pseudovirus-neutralization test (PNT) will be performed by François Anna (Institut Pasteur) to detect antibodies capable of inhibiting SARS-CoV-2 spike-mediated viral entry1. Concerning cytokine analyses, both Luminex-based and SiMOA digital ELISA are available that can quantitate various inflammatory cytokines in the nasopharynx of healthy donors, SARS-CoV-2-infected patients and COVID-19 convalescent individuals (D Duffy laboratory at the Institut Pasteur).

After the 6 first months of the present MUCOSA Project, we performed WP1 which is about to identify the nature and quantity of anti-SARSCov2 antibodies (IgM, IgG, IgA) in the mucosal samples that were already available at the time of study beginning through the Curiosa Protocol (T0, 3 and 6 months). The quantitation of these parameters in the nasal swab has been completed by Institut Pasteur using the S-flow technique for the 432 samples.
As proposed to complete our study, we included a time point at 12 months to further analyse antibody responses. The inclusions and corresponding sampling are finalized. 886 blood samples and 17 nasal swab samples were collected. As the vaccine induces antibody against the S protein while the natural infection also stimulates an anti-N response, asymptomatic infections in vaccinated patients are detected through an increase of the anti-N antibody titers. We already quantified IgG anti-S and anti-N antibodies for the 886 blood samples. The 17 nasal swabs are under quantification. All the samples positive for anti-S antibodies were analysed through pseudovirus-neutralization test (PNT).
Cytokine analyses, both Luminex-based and SiMOA digital ELISA are available that can quantitate various inflammatory cytokines in the nasopharynx of healthy donors, SARS-CoV-2-infected patients and COVID-19 convalescent individuals. The data are currently analysed at Institut Pasteur.
Raw data (systemic antibody levels, PNT levels, age, sex, anosmia/ageusia, vaccination or infection status and date) are being shared (early december) to “Santé Publique France” in order to participate to mathematical/statistical simulation of virus spreading and to further handle pandemic evolution.
The analysis (WP2 and WP3) will start as soon as all the data are available.

The project will quantify the prevalence of mucosal responses as compared to systemic ones and will enables to detect new asymptomatic or symptomatic re-infections during the current protracted second phase.
The data is shared with Public Health France, and the results will be published.

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How the local mucosal antibody response relates to the systemic response during SARS-CoV2 infection is still unclear. What is the respective role of local and systemic response in the protection against disease is also not known. Based on a cohort of 1900 Institut Curie workers followed for 4 time points after the first wave of infections and during the second one, we will assess the local immune response as compared the systemic antibody response and the clinical variables recorded through an e-CRF. A first analysis of the two first time points including: anti-N, anti-S IgG, and pseudo-neutralisation, associated with the clinical variables, has already been published. However, the local immune response was not assessed. Here, we plan to measure the local anti-N and anti-S Ig response in the available mucosal samples (n=283 at month 1-3 time-point; n= 157 at month 6). We will also obtain another blood draw and mucosal sampling at 12 months. This will allow a comparison between the systemic and local response and estimate the rate of asymptomatic secondary infections in relation with the type of primary response, clinical response, and vaccination since the epidemic is still ongoing.

Project coordination

Olivier LANTZ (Institut Curie)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

IC Institut Curie
IP Institut Pasteur
curie Institut Curie - Section Médicale
UII Unité d'Immunité Innée

Help of the ANR 79,968 euros
Beginning and duration of the scientific project: May 2021 - 12 Months

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