Heterologous Ad26/Ad5 adenovirus-vectored vaccines elicited SARS-CoV-2-specific antibody responses with potent Fc activities

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Presentation Time: 05:15 PM - 05:30 PM
Abstract ID: 4465 - B

Presenting Author:
Catarina E Hioe , Professor at Icahn Sch. of Med., Mount Sinai, James J. Peters VA Med. Ctr.

Abstract:

Several COVID-19 vaccines have been approved for clinical use worldwide. This study examined serum antibodies from participants receiving heterologous Ad26/Ad5 adenovirus-vectored Sputnik V vaccines. The spike-binding titers of vaccine-induced antibodies declined over six months, similarly to Fc-mediated antibody activities, while neutralization titers remained stable. We also compared antibodies elicited early by Ad26/Ad5 vaccines with those induced by LNP-mRNA vaccines (Pfizer/BioNTech or Moderna) or after SARS-CoV-2 infection. Anti-spike IgG1 was the predominant isotype and produced to high levels in the three groups. In addition to IgG1, the Ad26/Ad5 vaccines also induced IgG4 but not IgG2 and IgG3. In contrast, the LNP-mRNA vaccines elicited a full Ig spectrum encompassing IgM, IgG1-4, and IgA1-2, whereas convalescent COVID-19 patients displayed mainly IgM and IgA1 alongside IgG1. Despite these differences, neutralization potencies against early virus variants were comparable. However, the Ad26/Ad5 group, similar to the LNP mRNA group, had antibodies with greater capacities for complement binding than the COVID-19 group. The Ad26/Ad5-induced antibodies also showed a greater potency of binding Fcgamma receptors than those of the other two groups. Hence, antibodies of different Ig isotypes/subtypes and with greater Fc activities were elicited by COVID-19 vaccines, highlighting the distinctive quality of antibodies induced by vaccination versus virus infection.