1 INTRODUCTION
The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute
respiratory syndrome coronavirus (SARS‐CoV‐2), has persisted for more
than three years1, and numerous variants have emerged
globally. In early December 2022, China lifted its COVID-zero policy,
followed shortly by the quick spread of the SARS-CoV-2 Omicron variant
across most parts of the country.2 Although
vaccination with wild-type SARS-CoV-2 vaccines did not appear to provide
significant protection against Omicron in Beijing, most people only
experienced influenza-like symptoms. By February 2023, only sporadic
COVID cases were reported each day, indicating that
herd immunity against Omicron
variants was achieved in a relatively short period in China. However,
concerns remain regarding the effectiveness of this immunity against
future spillovers of SARS-CoV-2-like viruses.
To address this issue, we analyzed the neutralizing antibodies in sera
from wild-type SARS-CoV-2 vaccine recipients who
recovered from Omicron BF.7
variant infection by performing viral neutralizing assays with a
SARS-CoV-2-related pangolin coronavirus GX_P2V3. The
differences between SARS-CoV-2 and GX_P2V primarily lie in the spike
glycoprotein (S), a primary target for neutralizing antibody (Figure
S1). However, compared to SARS-CoV-2, the spike protein of pangolin-CoV
GX_P2V has a comparable binding affinity to human ACE2 but has a
distinct receptor binding domain (RBD)4 (Figure 1A),
making it a practical model for testing neutralizing antibodies against
unpredictable SARS-CoV-2 related viruses.