Abstract
Recent exposure to seasonal coronaviruses (sCoVs) may stimulate cross-reactive antibody responses against severe acute respiratory syndrome CoV 2 (SARS-CoV-2). However, previous studies have produced divergent results regarding protective or damaging immunity induced by prior sCoV exposure. It remains unknown whether pre-existing humoral immunity plays a role in vaccine-induced neutralization and antibody responses. In this study, we collected 36 paired sera samples from 36 healthy volunteers before and after immunization with inactivated whole-virion SARS-CoV-2 vaccines for COVID-19, and analyzed the distribution and intensity of pre-existing antibody responses at the epitope level pre-vaccination as well as the relationship between pre-existing sCoV immunity and vaccine-induced neutralization. We observed large amounts of pre-existing cross-reactive antibodies in the conserved regions among sCoVs, especially the S2 subunit. Excep t for a few peptides, the IgG and IgM fluorescence intensities against S, M and N peptides did not differ significantly between pre-vaccination and post-vaccination sera of vaccinees who developed a neutralization inhibition rate (%inhibition) <40 and %inhibition ≥40 after two doses of the COVID-19 vaccine. Participants with strong and weak pre-existing cross-reactive antibodies (strong pre-CRA; weak pre-CRA) had similar %inhibition pre-vaccination (10.9% ± 2.9% vs. 12.0% ± 2.2%, P=0.990) and post-vaccination (43.8% ± 25.1% vs. 44.6% ± 21.5%, P=0.997). Overall, the strong pre-CRA group did not show a significantly greater increase in antibody responses to the S protein linear peptides post-vaccination compared with the weak pre-CRA group. Therefore, we found no evidence for a significant impact of pre-existing antibody responses on inactivated vaccine-induced neutralization and antibody responses. Our research provides an important basis for inactivated SARS-CoV-2 vaccine use in the context of high sCoV seroprevalence.
Highlights
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, has led to widespread human and economic losses
All participants were negative both for SARS-CoV-2 nucleic acid on nasopharyngeal swab specimens by reverse transcriptase polymerase chain reaction (RT-PCR) assays and specific IgG/IgM antibody tests of serum samples by commercial enzyme-linked immunosorbent assay (ELISA) kits (BGI PathoGenesis Pharmaceutical Tech, China)
We examined the SARS-CoV-2 epitope-specific antibody responses in 36 individuals who were vaccinated with two doses of the Sinopharm inactivated COVID-19 vaccine
Summary
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, has led to widespread human and economic losses. The SARSCoV-2 belongs to the Coronaviridae family and the Coronavirinae subfamily, which are divided into four genera (a-, b-, g-, and d-CoVs). Both a and b CoVs mainly infect mammals, among which four seasonal CoVs (sCoVs), including aCoVs (NL63 and 229E) and b CoVs (OC43 and HKU1), are endemic globally and account for 10%–30% of upper respiratory tract infections [1]. SARS-CoV-2 is thought to induce antigen-specific antibody responses through S and N proteins. Antibodies targeting the RBD have been suggested to account for >90% of neutralizing activity in SARS-CoV-2 convalescent sera [3]. SARS-CoV-2 S protein has 23%–30% homology with four sCoVs [5]. Antibody titers induced by sCoVs are short-lived and fluctuate over time [8]
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