Study suggests loss of smell and brain inflammation are independent in COVID-19 biorxivpreprint institutpasteur Sorbonne_Univ_ unibern smell brain inflammation COVID19 coronavirus covid
By Bhavana KunkalikarSep 5 2022Reviewed by Danielle Ellis, B.Sc. In a recent study posted to the bioRxiv* preprint server, researchers assessed the association between neuroinvasion and anosmia observed during coronavirus disease 2019 .
The team assessed how different SARS-CoV-2 VOCs affected the clinical manifestations of infection compared to the ancestral Wuhan strain. In Vero-E6 cells, the researchers examined the in vitro growth curves of these viruses. Subsequently, SARS-CoV-2 Wuhan or the VOCs Gamma, Delta, or Omicron/BA.1 were administered intranasally to male golden hamsters, and the subjects were observed for four days after infection .
The impact of the infecting variant was, however, noted in the Gamma-infected animals that had the highest viral titers and the Omicron/BA.1-infected animals having the lowest. Notably, Delta-infected animals had the highest viral load. Genomic and sub-genomic SARS-CoV-2 RNA were found to be in equal measures in the lungs of all infected animals but in different amounts in the nasal turbinates.
The prevalence of olfactory dysfunctions varied depending on the VoC, with hamsters infected with Delta and Omicron/BA.1 exhibiting no indications of anosmia. Notably, all tested SARS-CoV-2 variants could effectively enter the central nervous system and infect the olfactory bulbs. The various VoCs can be distinguished based on spike mutations. Additionally, a few VoC isolates, including the Delta isolate used in this investigation, had deletions in the open reading frame -7 region.