Year: 2022
Type: dissertation
Study design: Observational Study
Abstract: The coronavirus responsible for the 2019 severe acute respiratory syndrome (SARS-CoV- 2) is a highly transmissible pathogen that threatens human health and public safety. It was recognized early on into the pandemic that the infection could lead to significant complications in addition to long-lasting symptoms in a significant proportion of those who were infected. Chronic fatigue, muscle and joint pain, as well as cognitive impairment are some of the symptoms reported by patients suffering from post-infectious syndrome, better known as long COVID (LC). Therefore, the devastating consequences of the pandemic have accelerated the development of prophylactic vaccines. Both infection-stimulated and vaccine-mediated immunity rely on the generation of antigen (Ag)-specific T cells, memory B cells and antibodies. Consequently, the ability of SARS-CoV-2 Ag to promote robust immune responses in individuals who have developed LC as well as in immunocompromised individuals is questioned. Thus, this study aims to characterize the immune responses to SARS-CoV-2 Ag in these two groups of individuals. PBMC and plasma samples from previously infected individuals without LC and individuals with LC (BQC-19) were used to analyze the B cell response with ancestral strain and Omicron variant receptor binding domain (RBD) fluorescent probes by flow cytometry, as well as SARS-CoV-2 Ag-specific plasma responses by ELISA. Sequential PBMC and plasma samples from vaccinated rheumatoid arthritis (RA) patients were used to analyze T responses to an Ag pool by activation induced marker assay (AIM). Their B and antibody responses were assessed with the same techniques as those used for the LC aim. BQC-19 samples analysis showed that RBD+ B cells frequencies were higher in the LC group when compared with the COVID and negative control groups, and that the antibody response to the Omicron variant was weaker than to the ancestral strain. Studies performed on immunocompromised individuals indicated that B responses following vaccination were less dominant in RA patients, although their T responses appeared to be maintained. It was also found that a single dose of mRNA vaccine was not sufficient to increase anti-RBD antibody levels. Briefly, our results suggest that the immune responses in LC as well as RA individuals to Ag differ from those observed in healthy individuals.
Author: Limoges, Marc-André
Language: French
Subfield: Infectious Diseases
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7201922297