Oral Epithelial Cells Expressing Low or Undetectable Levels of Human Angiotensin-Converting Enzyme 2 Are Susceptible to SARS-CoV-2 Virus Infection In Vitro

• Published in: Pathogens (Basel) Vol. 12; no. 6; p. 843
• Main Authors: Ebraham, Laith, Xu, Chuan, Wang, Annie, Hernandez, Cyril, Siclari, Nicholas, Rajah, Divino, Walter, Lewins, Marras, Salvatore A E, Tyagi, Sanjay, Fine, Daniel H, Daep, Carlo Amorin, Chang, Theresa L
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.06.2023; MDPI
• Subjects: ACE inhibitors; ACE2; Angiotensin; Angiotensin-converting enzyme 2; Antibodies; Brief Report; CD147 antigen; Cells; Conversion; COVID-19; Disease transmission; Dosage and administration; Enzymes; Epithelial cells; Epithelium; Exocrine glands; Heparan sulfate; Infections; Laboratories; Management; Oral cavity; oral epithelial cells; Oral infection; Peptidyl-dipeptidase A; Prevention; Proteins; Public health; Receptors; Replication; Risk factors; RNA polymerase; Salivary gland; Salivary glands; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Telomerase reverse transcriptase; Testing; Tongue; Viral antibodies; Viral diseases; Viral infections; Virus diseases; Viruses; China; La Jolla California; United States > US; oral epithelial cells; SARS-CoV-2
• DOI: 10.3390/pathogens12060843
• ISSN: 2076-0817

The oral cavity is thought to be one of the portals for SARS-CoV-2 entry, although there is limited evidence of active oral infection by SARS-CoV-2 viruses. We assessed the capacity of SARS-CoV-2 to infect and replicate in oral epithelial cells. Oral gingival epithelial cells (hTERT TIGKs), salivary gland epithelial cells (A-253), and oral buccal epithelial cells (TR146), which occupy different regions of the oral cavity, were challenged with replication-competent SARS-CoV-2 viruses and with pseudo-typed viruses expressing SARS-CoV-2 spike proteins. All oral epithelial cells expressing undetectable or low levels of human angiotensin-converting enzyme 2 (hACE2) but high levels of the alternative receptor CD147 were susceptible to SARS-CoV-2 infection. Distinct viral dynamics were seen in hTERT TIGKs compared to A-253 and TR146 cells. For example, levels of viral transcripts were sustained in hTERT TIGKs but were significantly decreased in A-253 and TR146 cells on day 3 after infection. Analysis of oral epithelial cells infected by replication-competent SARS-CoV-2 viruses expressing GFP showed that the GFP signal and SARS-CoV-2 mRNAs were not evenly distributed. Furthermore, we found cumulative SARS-CoV-2 RNAs from released viruses in the media from oral epithelial cells on day 1 and day 2 after infection, indicating productive viral infection. Taken together, our results demonstrated that oral epithelial cells were susceptible to SARS-CoV-2 viruses despite low or undetectable levels of hACE2, suggesting that alternative receptors contribute to SARS-CoV-2 infection and may be considered for the development of future vaccines and therapeutics.