Resistance to COVID-19 vaccines in Russian bats containing ACE2-dependent sarvecoviruses

In a recent study published in PLoS pathogenresearchers investigate receptor tropism and serological cross-reactivity of spike (S) protein receptor-binding domains (RBDs) from two clade 3 sarbecoviruses found in Russian rhinolophus (horseshoe) bats. Did: Khosta-1 in Rhinolophus ferrumequinum Khosta 2 in R. Cabassiderosdiverges from the receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus-1 (SARS-CoV-1) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

The zoonotic spread of the SARS-CoV-2 sarbecovirus led to the 2019 coronavirus disease (COVID-19) pandemic. Several sarvecoviruses have been found among Asian bats. However, most of them do not infect humans. Researchers are accelerating virus detection efforts globally and expanding genome databases of zoonotic and circulating sarvecoviruses.

The authors and others have classified the RBDs of sarvecoviruses into three clades. The Asian bat clade 2 virus has two deletions and does not bind to hACE2. European and African bat clade 3 viruses contain a single deletion and bind to hACE2. In 2021, a virus was detected in Chinese bats containing a clade 4 that also binds hACE2.

About research

In the present study, investigators investigated host cell infection by S of Russian bat sarvecovirus and their neutralization by monoclonal antibodies (mAbs) and vaccinated donor sera.

A full-length Khosta S gene was synthesized and the SARS-CoV-1 S RBD was replaced with the RBD of the Khosta virus to generate a chimeric S expression plasmid. In addition, chimeric S RBDs from other previously tested clade 3 viruses (BM48-31, Uganda), SARS-CoV-2, and a related RaTG13 virus were included in the comparative analysis. The chimeric S construct generated VSV (vesicular stomatitis virus) pseudotyped VLPs (virus-like particles) carrying chimeric SARS-CoV-2 S and Khosta RBD, mimicking the potential recombinant threat posed by the Khosta virus.

Additionally, to test viral compatibility with human cells, Huh-7 (a human hepatocyte cell line) cells were infected with VLPs harboring the chimeric Khosta S RBD. A receptor tropism study was performed to characterize potential Costavirus receptors. In this study, baby hamster kidney (BHK) cells were transfected with the known human orthologue of her CoV receptor and then infected with virus pseudotypes. Human entry efficiency between viral S protein and human ACE2 (hACE2) was further evaluated by infecting hACE2-expressing 293T cells.

293T “producer cells” were lysed and lysates were subjected to Western blot analysis. To investigate the protein interaction between Khosta 2 and hACE2 relative to other clade 1 S RBDs, Khosta 2 RBD structural predictions were made based on previously published data, which were compared with multiple sequence alignments ( MSA) to ACE2-bound SARS-CoV-. 1 and SARS-CoV-2 co-structures for phylogenetic assessment.

Pseudotype experiments were repeated with sera obtained from vaccinated individuals. To compare neutralization of Khosta 2 and SARS-CoV-2 variants of concern (VOCs), SARS-CoV-2 Omicron VOC S RBD was generated and vaccinated (double dose with Pfizer or Moderna vaccines) Serum samples obtained from 6 individuals were tested. ), four uninfected donor individuals and three vaccinees with breakthrough Omicron infection.

Human orthologs of ACE2, APN (aminopeptidase N) and DPP4 (dipeptidyl peptidase IV) and plasmid S sequences from human CoV (HCoV)-229E, Middle East respiratory syndrome CoV (MERS-CoV), and SARS-CoV-1 was obtained. A neutralization assay was performed using sera from vaccinated donors and the SARS-CoV-2 RBD-specific mAb, bamuranivimab.

Results and discussion

Exogenous proteases mediated Khosta-1 RBD entry into Huh-7 cells. However, the addition of proteases did not promote Khosta-1 RBD entry into BHK cells transfected with several CoV receptors, and trypsin-dependent Khosta-1 entry into Huh-7 cells was inhibited by hACE2. It shows that you don’t depend on it. In contrast, the addition of trypsin enhanced the receptor-dependent entry signals of SARS-CoV-2 RBD and Khosta 2 RBD, indicating that Khosta 2 RBD utilized hACE2 receptors for cell infection. However, full-length Khosta 2 S was less infectious than SARS-CoV-based chimeric S.

Khosta 2 RBD infected hACE2-expressing cells with cell entry levels comparable to RaTG13, a hACE2-binding bat salvecovirus that is highly similar to SARS-CoV-2 RBD. Both African clade 3 RBDs also showed his hACE2 binding, but with considerably lower efficiency than SARS-CoV-2. In contrast to the hACE2 receptor findings, only HCoV-229E and MERS-CoV infected APN- and MERS-CoV DPP4-expressing cells, respectively.

astonishing, Omicron S was effectively neutralized by bamuranivimab, whereas SARS-CoV-2 S, including Khosta 2 RBD, showed modest resistance (and complete resistance to the Wuhan-Hu-1 strain). 2 RBDs. Similar findings were observed when sera from vaccinated donors were used.

Since Khosta 2 RBD and SARS-CoV-2 RBD share only 60% similarity, they may be more resistant to neutralization by Khosta 2 than SARS-CoV-2, and the neutralization response with vaccination is mainly It was aimed at RBD. Bamuranivimab contacts 17 SARS-CoV-2 Wuhan-Hu-1 strain residues, 10 of which are shared with Khosta 2. Khosta 2 encodes G435 at a site similar to E484 in SARS-CoV-2.

Overall, the study results highlighted the hACE2 receptor preference in Khosta 2 clade 3 viruses using pseudotyped VLPs containing chimeric and full-length clade 3 S proteins.Pseudotyped VLPs Containing Khosta 2 RBD Encoding Recombinant SARS-CoV-2 S Resist Neutralization, New Recombinant Salbecoviruses Circulating Beyond Asia Threaten Current COVID-19 Vaccines indicates that there is a possibility Effectiveness.