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Cloning and size of SARS-CoV-2 reactive CD4 + T cells in post-vaccinated COVID-19 convalescent patients

Scientists have set a precedent for developing a vaccine that protects individuals from the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of the coronavirus disease (COVID-19) pandemic. I have been working at a speed that is not. Some COVID-19 vaccines have received an Emergency Use Authorization (EUA) from regulatory agencies around the world, after which vaccination programs have begun in most countries around the world.

study: SARS-CoV-2 vaccination diversifies the CD4 + spike-responsive T cell repertoire of previously infected patients with SARS-CoV-2.. Image Credits: Design_Cells / Shutterstock

Background

Previous studies have shown that the COVID-19 vaccine developed by Pfizer-BioNTech and Moderna induces potent CDs.4 years old and over T cell response.Researchers have stated that unlike natural infections that require extrinsic or endogenous processing of some viral proteins, mRNA vaccines result in transcription and translation of SARS-CoV-2 spikes (S). GlycoproteinProvides strong immune protection against various antigenic spike-derived epitopes.

Scientists have stated that the evidence available for the immune response of COVID-19 convalescent individuals vaccinated with SARS-CoV-2 vaccine is very limited.Serum antibody titers are usually assessed to study SARS-CoV-2 immunity and CD4 length.+ Helper T cell response (immune memory cell).These cells determine the concentration of cytotoxicity T cells And antibody levels upon reinfection with SARS-CoV-2.

Previous studies revealed cross-reactivity of CD4+ T cells between SARS-CoV-2 and endemic colds coronavirus (CCC). The immunological memory of cross-reactive T cells should play an important role in the development of the current and future zoonotic coronavirus. Importantly, one study reported that an endogenous T cell response induced by COVID-19 infection protected macaques from reinfection. However, it is not yet clear whether vaccination of COVID-19 convalescent patients (CCP) provided additional protection against reinfection, or whether natural infections provided sufficient protection.

Previous studies have shown that mRNA vaccination increases the COVID-19 antibody titer of CCP over spontaneous infection, but the response of T cells to vaccination in this group is unknown. Therefore, it is important to determine the clonality of the vaccine-induced T cell repertoire and evaluate the post-vaccination changes in the SARS-CoV-2 reactive T cell repertoire in CCP.

New research

New research published in eBioMedicine Focuses on determining the clonality and level of SARS-CoV-2 reactive CD4+ CCP T cells after vaccination. Researchers also compared this level with vaccinated CCPs.

Related article

In this study, scientists performed a specific T cell viral enhancement (ViraFEST) assay to determine SARS-CoV-2 reactivity at the CD4TCRVβ clone level. This T cell assay can reliably identify antigen-specific T cell receptor (TCR) chronotypes. The ViraFEST assay helped assess the SARS-CoV-2 specific repertoire generated by vaccination and spontaneous infection. One of the advantages of this assay over the traditional ELISPOT or intracellular cytokine stimulation assay is the ability to determine reactivity and repertoire at the clonal level. This helped investigate whether the immune response after COVID-19 vaccination enables cross-reactivity or SARS-CoV-2 monoreactive T cell clones.

Main survey results

Researchers have found the diversity of the TCR repertoire, more precisely CD4.+ T cells are essentially multifunctional, thereby providing more effective immune protection. In this study, researchers found that COVID-19 vaccination induces monospecific SARS-CoV-2 reactive T cells with better functionality.

Several studies have associated high avidity TCR with greater removal of the virus. These studies emphasize that vaccination, even in CCP, is essential for producing a long-lived and dynamic repertoire of SARS-CoV-2 reactive T cells. The results of this study are consistent with the above study. In addition, current studies have shown that over time, all patients after vaccination showed significant clonal contraction in both groups, namely vaccine-induced and infection-induced clones. This finding supports previous reports that T cell responses decline over time.

In the future, more studies need to be conducted, especially to assess the duration of vaccine-induced immunization after hybrid vaccination and booster immunization. There is little evidence to explain why COVID-19 vaccination produces a diverse TCR repertoire compared to natural infections. However, scientists speculate that the mRNA vaccine induces spike-specific T cells that are effective against a wide range of highly functional spike epitopes in the presence of IL-2 and IFN-γ. These usually occur due to the Th1 memory response of previously infected cells.

Scientists in this study believe that an improved formulation of the mRNA vaccine and a single-antigen approach will help activate a unique T cell repertoire that is different from that activated during natural infections. .. In addition, optimized spike transcripts and activation of innate sensing molecules can lead to different spike epitopes presented on MHC class II molecules. The authors stated that a single antigen could reduce the effects of epitope competition with nucleocapsids and non-structural epitopes, thereby inducing a well-defined vaccine-induced repertoire.

Conclusion

One of the limitations of this study is its small research cohort. However, the authors found that the results of this study provided a better understanding of the immune repertoire induced by the COVID-19 vaccine in individuals with a history of SARS-CoV-2 infection. This study emphasized the importance of vaccination in COVID-19 convalescent individuals to increase the diversity of T cell responses to SARS-CoV-2 virus.

The story first appeared in News Medical

https://industrialnews.co.uk/clonality-and-magnitude-of-sars-cov-2-reactive-cd4-t-cells-in-covid-19-convalescent-patients-after-vaccination/?utm_source=rss&utm_medium=rss&utm_campaign=clonality-and-magnitude-of-sars-cov-2-reactive-cd4-t-cells-in-covid-19-convalescent-patients-after-vaccination Cloning and size of SARS-CoV-2 reactive CD4 + T cells in post-vaccinated COVID-19 convalescent patients

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