BackgroundUnderstanding viral infection of the olfactory epithelium is essential because smell loss can occur with coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), and because the olfactory nerve is an important route of entry for viruses to the central nervous system. Specialized chemosensory epithelial cells that express the transient receptor potential cation channel subfamily M member 5 (TRPM5) are found throughout the airways and intestinal epithelium and are involved in responses to viral infection.ResultsHerein we performed deep transcriptional profiling of olfactory epithelial cells sorted by flow cytometry based on the expression of fluorescent protein markers for olfactory sensory neurons and TRPM5 in the mouse (Mus musculus). We find profuse expression of transcripts involved in inflammation, immunity and viral infection in TRPM5-expressing microvillous cells and olfactory sensory neurons. These cells express the Tmprss2 transcript that encodes for a serine protease that primes the SARS-CoV-2 spike protein before entry into host cells. Intranasal infection with herpes simplex virus type 1 (HSV-1) elicited a decrease in olfactory sensory neurons.ConclusionOur study provides new insights into a potential role for TRPM5-expressing cells in viral infection of the olfactory epithelium. We find that, as found for solitary chemosensory cells (SCCs) and brush cells in the airway epithelium, and for tuft cells in the intestine, the transcriptome of TRPM5-expressing microvillous cells and olfactory sensory neurons indicates that they are likely involved in the inflammatory response elicited by viral infection of the olfactory epithelium.

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Background Understanding viral infection of the olfactory epithelium is essential because the olfactory nerve is an important route of entry for viruses to the central nervous system. Specialized chemosensory epithelial cells that express the transient receptor potential cation channel subfamily M member 5 (TRPM5) are found throughout the airways and intestinal epithelium and are involved in responses to viral infection. Results Herein we performed deep transcriptional profiling of olfactory epithelial cells sorted by flow cytometry based on the expression of mCherry as a marker for olfactory sensory neurons and for eGFP in OMP-H2B::mCherry/TRPM5-eGFP transgenic mice (Mus musculus). We find profuse expression of transcripts involved in inflammation, immunity and viral infection in TRPM5-expressing microvillous cells compared to olfactory sensory neurons. Conclusion Our study provides new insights into a potential role for TRPM5-expressing microvillous cells in viral infection of the olfactory epithelium. We find that, as found for solitary chemosensory cells (SCCs) and brush cells in the airway epithelium, and for tuft cells in the intestine, the transcriptome of TRPM5-expressing microvillous cells indicates that they are likely involved in the inflammatory response elicited by viral infection of the olfactory epithelium.