Comparison and monitoring of antibody response in convalescent and healthy vaccinated individuals against RBD and PCS of SARS-CoV-2 spike protein

Abstract

The prevalence of SARS-CoV-2 as a global health threat has called for population-wide vaccination to curb COVID-19. Hence, the World Health Organization (WHO) has approved several platforms of SARS-CoV-2 vaccines for emergency use. Therefore, a more comprehensive study on the immune response induced by vaccines in diverse individuals is still required. Here, we expressed a local variant of SARS-CoV-2 receptor-binding domain (RBD) and protease cleavage site (PCS), playing a vital role in binding and fusion in Rosetta (DE3). We then characterized it through SDS-PAGE analysis and western blotting. Moreover, we compared and monitored ChAdOx1 nCoV-19 vaccination-induced antibody response in convalescent and healthy vaccinated individuals after the first and second vaccine doses through serologic assay against RBD and PCS, which have not yet been compared. We investigated a cohort of 100 sera samples; based on our parameters, 25 serum samples were selected as convalescent samples and 25 serum samples as healthy samples for comparison. These findings demonstrate that most of the convalescent sera show more reactivity with PCS (80%) than with RBD (56%). Interestingly, IgG antibody response against PCS was more significant in both pre- and post-vaccination in convalescent individuals than in healthy individuals. Indeed, anti-RBD antibody titers were most significant in pre-vaccination and post–first vaccination in convalescent individuals than in healthy individuals and not in pre-vaccination and post–second vaccination. Besides monitoring IgG antibody response against COVID-19, these findings could shed light on the progress, assessment, and efficacy evaluation of SARS-CoV-2 vaccines.

Communicated by Ramaswamy H. Sarma

Keywords:

• Antibody response
• receptor-binding domain
• protease cleavage site
• SARS-CoV-2

Author contributions

Mojtaba Ranjbar designed the research, performed virtual screening and Hadi Hassannia analyzed molecular dynamics simulation, and performed the immno-informatics analysis. Fatemeh Khakdan conceived interpretation of data and drafting of the manuscript. Seyed Amir Hossein Mohammadzadeh Hosseini Moghri performed the computational work and experimental research.

Data availability statement

All data generated or analysed during this study are included in this published article

Disclosure statement

No conflict of interest was reported by the authors.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.