SARS-CoV-2 recombinant spike protein induces cell apoptosis in rat taste buds

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause loss or alteration of taste and smell as early symptoms or sequelae, but the detailed mechanism behind this phenomenon remains unclear. Here, we investigated whether the SARSCoV-2 spike protein induces taste cell apoptosis and expression of the apoptosis-related cytokine TNF-a in male Sprague-Dawley rats. Terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-fluorescein nick end labeling (TUNEL) assay results revealed a significantly higher apoptosis index for taste cells in the SARS-CoV-2 group than for those in the control group. An immunohistochemistry analysis indicated significantly more TNF-a-positive cells in the SARS-CoV-2 group compared with the control group. These data suggest that the SARS-CoV-2 spike protein promotes taste cell apoptosis and the release of apoptosis-related cytokine TNF-a, implicating its contribution to the taste malfunction caused by coronavirus disease 2019 (COVID-19).(c) 2022 Association for Dental Sciences of the Republic of China. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).

Automated summary

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause taste and smell alterations, and this study investigated the mechanism behind it. The spike protein of SARS-CoV-2 induced taste cell apoptosis and increased expression of the apoptosis-related cytokine TNF-a. These findings suggest that the spike protein contributes to the taste malfunction caused by COVID-19.