Immunogenicity of SARS-CoV-2 antibody responses in immune-naive children and adults

*Important Notices: This news article is a review of a preliminary scientific report that was not peer-reviewed at the time of publication. Since its first publication, the scientific report has now been peer-reviewed and approved for publication in the Scientific Journal. Links to preliminary and peer-reviewed reports can be found in the sources section at the bottom of this article. see the source

Recent studies under review in Journal of Clinical Immunology Now available on preprint servers Research Square* Contribution of antibodies to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike receptor binding domain (RBD) in vaccinated adults and children and in individuals naturally infected with SARS-CoV-2 variants Analyze the

study: Infections and vaccines induce spike antibody responses to SARS-CoV-2 variants, a concern in immune-naive children and adults. Image credit: Yurii_Yarema / Shutterstock.com

SARS-CoV-2 infection in adults and children

According to the World Health Organization (WHO), survival of emerging SARS-CoV-2 important variants (VOI) and variants of concern (VOC) depends on viral infectivity, immune evasion, and transmissibility . The characteristics of these viruses differ between VOI and VOC. This may be due to specific mutations throughout the spike protein.

Examination of antibody responses to viral variants can help elucidate the effects of mutations within the spike protein and in epistasis, where mutations at one site affect others. However, information on the humoral immunogenicity of SARS-CoV-2 and protection against emerging variants in children is limited.

Differences between the innate and adaptive immune systems in adults and children lead to different immune responses following SARS-CoV-2 infection. For example, several studies have reported different humoral adaptive responses in children compared to adults. To this end, some have reported higher antibody titers and neutralization to VOCs in children, while others have reported higher titers but similar neutralization compared to adults.

Overall, the low prevalence of childhood coronavirus disease 2019 (COVID-19) before the emergence of the SARS-CoV-2 Omicron VOC was due to an increase in asymptomatic infections in this patient population. There is a possibility. Children infected with Omicron still have less severe illness than adults, but the viral loads of unvaccinated children and adults appear to be similar.

About research

The current study included 83 immunization-naive adults and children. Of the pediatric study participants, 16 of her and 5 adults in the same household were infected with Early Clade SARS-CoV-2, compared with 15 nonimmune children and 11 of her of household adults were infected with SARS-CoV-2 Delta variants. In addition, eight non-immune children and eight household adults were infected with Omicron variants.

All study participants naturally infected with either Early Clade, Delta, or Omicron strains were positive in polymerase chain reaction (PCR) assays.

Sera were collected from 24 individuals vaccinated with ChAdOx1 and BNT162b2. Serum collection was performed within 35 days after he received his second dose of vaccine.

All vaccinated adults and children had no previous SARS-CoV-2 infection. In addition, 48 healthy, non-inflammatory disease pre-pandemic control serum samples were included to detect patient seropositivity for the spike variant.

Detection of spike antibody immunoreactivity in patient sera was accomplished by a flow cytometry cell-based assay.

Survey results

All PCR-positive patients with at least 10 days of virus exposure were seropositive for antibodies against the Early Clade Spike (D614) and D614G strains of SARS-CoV-2. Levels of immunoglobulin A (IgA) and IgG antibodies were similar in children and adults 1 to 6 months after exposure to the virus, although higher levels of IgM antibodies were observed in adults.

Levels of IgA, IgG, and IgM peaked at a median of 30 and 32 days after virus exposure in adults and children, respectively. Early clade spike IgA and IgG levels persisted up to 7 months after virus exposure, whereas spike IgM levels became negative approximately 163 days after exposure.

A significant difference in spiked IgG levels was reported between vaccinated and naturally infected individuals. Higher levels of early clade spike IgG antibodies (D614) were observed in children and adults who received the early clade-based her BNT162b2 vaccine compared with those who received the ChAdOx1 vaccine.

A decrease in spiked IgG levels was observed for VOCs spike proteinChildren infected with the early clade had higher titers of D614G-spiked IgG, whereas vaccinated children had higher titers to Omicron VOCs. However, an adult infected with Omicron and Delta had higher titers across VOCs and was less likely to experience severe her COVID-19 compared to children.

Delta-infected children and adults had 3-fold and 1.8-fold higher levels of Early Clade-spiked IgG, respectively, compared to Delta-spiked. antigenOmicron-infected children and adults had 5- and 3-fold, 8- and 4-fold, and 11- and 6-fold higher levels of Early Clade-spiked IgG compared to BA.5, BA.2, and BA had a .1 spiked IgG, respectively.

Antibodies generated by natural infection with the early clade SARS-CoV-2 showed reduced binding to all VOCs. However, delta- and omicron-infected individuals showed stronger binding to gamma, beta, and alpha VOCs compared to individuals infected with the early clade SARS-CoV-2.

All individuals showed limited binding to the Omicron VOC. Moreover, immunoreactivity among vaccinated cohorts was similar to early clade-infected patients.

The presence of the 484Q mutation in the kappa spike protein and the 478K mutation in the delta spike protein may improve antibody binding and increase immunoreactivity in delta-infected individuals. Similar results were observed when lysine (K) at position 484 was replaced with glutamic acid (Q) in beta, eta, and gamma spike proteins.

Early clade-infected individuals showed strong binding to eta. Strong immunogenicity was also observed for all naturally infected and vaccinated individuals.

Moreover, the presence of N501Y and E484K reduced the immunogenicity of Omicron, which was further enhanced by the S477N mutation. However, this reduction was compensated by Q498R, an epistatic contact mutation in N501Y.

Conclusion

Taken together, the results of this study reveal important molecular features for broad immunoreactivity and high antibody titers. These observations may aid in the development of vaccines that provide broad protective adaptive immune responses and in global serosurveillance efforts.

Limitations

The sample size of naturally infected individuals was small. An additional limitation was the unknown viral load in naturally infected individuals.

In addition, some participants may have suffered asymptomatic reinfection during follow-up, which may have resulted in very low spike antibody titers. Finally, no studies were performed on peripheral cells.

*Important Notices

research plaza We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.