Th163 - Rapid Diagnostic Test for Assessment of Cellular Immune Response in a Viral Infection as a Model

Mireia Bernuz, Biosensing and Bioanalysis Group, Institute of Biotechnology and Biomedicine. – Grup de Sensors i Biosensors, Departament de Química, – Universitat Autonoma de Barcelona; Juan Porras, Biosensing and Bioanalysis Group, Institute of Biotechnology and Biomedicine – Grup de Sensors i Biosensors, Departament de Química, – Universitat Autonoma de Barcelona; Natalia Egri, Department of Immunology, Centre de Diagnòstic Biomèdic, Hospital Clinic of Barcelona – Hospital Clinic of Barcelona; Europa Azucena González-Navarro, Department of Immunology, Centre de Diagnòstic Biomèdic, Hospital Clinic of Barcelona – Hospital Clinic of Barcelona; Juan Manel, Department of Immunology, Centre de Diagnòstic Biomèdic – Hospital Clinic of Barcelona; Isabel Pividori, Biosensing and Bioanalysis Group, Institute of Biotechnology and Biomedicine. – Grup de Sensors i Biosensors, Departament de Química, – Universitat Autonoma de Barcelona

Abstract Text: During the recent SARS-CoV-2 outbreak, there has been a recognized need of evaluating the adaptative immunological status, not only in infected individuals, but also in the vaccinated population. While the humoral immune response has been extensively assessed, the cellular immune response has received less attention due to the challenges of transferring it into a rapid diagnostic test. Consequently, there is a demand for the development of a rapid and user-friendly test for detecting activated T cells. This study is based on measuring interferon-gamma production as an indirect assessment of specific T cells. It uses the early expression of transcripts, amplifying them through PCR to targeted it in a paper-based rapid test. SARS-CoV-2 infection serves as a model for evaluating IFNγ transcripts in COVID-19 patients using a lateral flow assay. Whole blood of infected and non-infected individuals (both vaccinated) is incubated with Spike and Nucleocapsid peptide mixture followed by an immunomagnetic separation of the CD3+ T cells and IFNγ double-tagging RT-PCR. In parallel, non-stimulated blood sample are included as IFNγ basal expression. IFNγ increment is assessed by comparing the intensity of LFA signal from stimulated versus basal samples with a smartphone. Moreover, a time course is conducted to track the signal over time in the individuals with a specific T cell response. In summary, IFNγ-LFA is a one-day test, capable of assessing the cellular immune response up to two months and suitable for point-of-care applications as it requires minimal equipment.