Abstract
The current COVID-19 pandemic caused by constantly emerging SARS-CoV-2 variants still poses a threat to public health worldwide. Effective next-generation vaccines and optimized booster vaccination strategies are urgently needed. Here, we sequentially immunized mice with a SARS-CoV-2 wild-type inactivated vaccine and a heterologous mutant RBD vaccine, and then evaluated their neutralizing antibody responses against variants including Beta, Delta, Alpha, Iota, Kappa, and A.23.1. These data showed that a third booster dose of heterologous RBD vaccine especially after two doses of inactivated vaccines significantly enhanced the GMTs of nAbs against all SARS-CoV-2 variants we tested. In addition, the WT and variants all displayed good cross-immunogenicity and might be applied in the design of booster vaccines to induce broadly neutralizing antibodies.
Highlights
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to more than 200 million infections and 4 million deaths worldwide since the outbreak began
A third booster dose based on conventional two-dose vaccination is usually considered as a direct and effective strategy to enhance the immune responses such as the titer of neutralizing antibodies
It is unclear whether the sequential immunization with vaccines based on different platforms could increase the antibody response to SARS-CoV-2 variants
Summary
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to more than 200 million infections and 4 million deaths worldwide since the outbreak began. A third booster dose based on conventional two-dose vaccination is usually considered as a direct and effective strategy to enhance the immune responses such as the titer of neutralizing antibodies (nAbs). Song et al Virology Journal (2022) 19:2 strategy may improve the levels of nAbs more effectively [3] It is unclear whether the sequential immunization with vaccines based on different platforms could increase the antibody response to SARS-CoV-2 variants. We sequential immunized mice with a wild-type (WT) inactivated vaccine and a mutant receptor-binding domain (RBD) vaccine, and evaluated the neutralizing antibody response to SARS-CoV-2 WT strain or variants including Beta, Delta, Alpha, Iota, Kappa, or A.23.1, which will offer more options choices in vaccination strategies to control the current COVID19 pandemic
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