Recovery of anosmia in hamsters infected with SARS-CoV-2 is correlated with repair of the olfactory epithelium

Abstract

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for a pandemic affecting billions of people worldwide. Apart from the extreme global economic impact, the pandemic will likely have a lasting impact through long-term sequelae not yet fully understood. Fully understanding the mechanisms driving the various symptoms and sequelae of SARS-CoV-2 infection will allow for the eventual development of therapeutics to prevent or treat such life-altering symptoms. In this study, we developed a behavioral test of anosmia in SARS-CoV-2-infected hamsters. We find a moderately strong correlation between the level of anosmia and the score of histological damage within the olfactory epithelium. We also find a moderately strong correlation between the level of anosmia and the thickness of the olfactory epithelium, previously demonstrated to be severely damaged upon infection. Thus, this food-searching behavioral test can act as a simple and effective screening method in a hamster model for various therapeutics for SARS-CoV-2-related anosmia.

SARS-CoV-2 infection in hamsters and humans results in lasting and unique systemic perturbations after recovery

“…Alternatively, SARS-CoV-2 infection of olfactory bulbs may result in loss of a physical barrier, enabling the introduction of microbiome commensals which could contribute to the inflammatory profile. This latter hypothesis is supported by recent evidence that SARS-CoV-2 can induce gross morphological changes in the olfactory epithelium characterized by thinning and sloughing of the tissue that would normally prevent bacterial commensals from interacting with the OB ( 96 ). The extent to which the olfaction system contributes to the persistent inflammatory processes described within our study remains to be determined.…”

SARS-CoV-2 Omicron variant causes mild pathology in the upper and lower respiratory tract of Syrian golden hamsters (Mesocricetus auratus)

“…SARS-CoV-2 primarily targets the sustentacular cells in the olfactory mucosa, leading to a transient, massive necrosis and disintegration of the epithelium 21 . This phenomenon in hamsters is associated with the development of anosmia, a frequent clinical feature of COVID-19 patients [21][22][23] . In addition, it is also reported in some patients and in hamsters that the development of prolonged loss of smell could be caused by virus persistence in the olfactory mucosa 24 .…”

Animal Models for COVID-19 Therapeutic Development: Where We Are and Where We Need to Go

“…Olfactory and taste dysfunctions are common in mildly symptomatic COVID-19 patients. The food-searching behavioral test showed that anosmia may happen in SARS-CoV-2-infected hamsters, and the level of anosmia was associated with olfactory epithelium damage (Reyna et al, 2022). In addition, high titers of SARS-CoV-2 were found in the hamster lungs and intestines.…”