SARS-CoV-2 Omicron variant causes mild pathology in the upper and lower respiratory tract of hamsters

Abstract

Since its discovery in 2019, multiple variants of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have been identified. This study investigates virus spread and associated pathology in the upper and lower respiratory tracts of Syrian golden hamsters at 4 days post intranasal SARS-CoV-2 Omicron infection, in comparison to infection with variants of concern (VOCs) Gamma and Delta as well as ancestral strain 614 G. Pathological changes in the upper and lower respiratory tract of VOC Omicron infected hamsters are milder than those caused by other investigated strains. VOC Omicron infection causes a mild rhinitis with little involvement of the olfactory epithelium and minimal lesions in the lung, with frequent sparing of the alveolar compartment. Similarly, viral antigen, RNA and infectious virus titers are lower in respiratory tissues of VOC Omicron infected hamsters. These findings demonstrate that the variant has a decreased pathogenicity for the upper and lower respiratory tract of hamsters.

Neuroinvasion and anosmia are independent phenomena upon infection with SARS-CoV-2 and its variants

“…Indeed, we show that all VoCs can infect golden hamsters and promote lung inflammation, including Omicron/BA.1 differently from other reports (Abdelnabi et al, 2022;Halfmann et al, 2022), probably due to infectious doses or viral isolates. A "variant-effect" in the clinical presentation and in the tissue-related inflammation was evident, with disease severity presenting the following order: SARS-CoV-2 Wuhan > Gamma > Delta > OmicronBA.1, which supports the hypothesis that Omicron/BA.1 evolution has resulted in a tropism more restricted to the upper respiratory tract, thereby causing a less severe clinical disease (Armando et al, 2022;Chen et al, 2022;Hui et al, 2022;Yuan et al, 2022). Notwithstanding, the neuroinvasiveness, neurotropism, and neurovirulence characteristics of Omicron/BA.1 is similar to the other SARS-CoV-2 variants.…”

Case report: Lympho-histiocytic meningoencephalitis with central nervous system vasculitis of unknown origin in three dogs

“…201500102, rabbit polyclonal), anti-neospora caninum (Dr. Schares, Institute of Epidemiology, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany, monoclonal mouse), anti-herpes-suis (Dr. Eskens, Veterinär-Untersuchungsamt Mittelhessen, Germany, polyclonal mouse), anti-pan-Morbillivirus (D110; kind gift from Prof. Dr. A. Zurbriggen, University of Bern, Switzerland, mouse monoclonal), anti-tick born encephalitis virus (K-D-3.BA; Prof. Holzmann, Department of Virology, University of Vienna, Austria, rabbit polyclonal) antibody. Additionally, IHC for the detection of severe acute respiratory syndrome coronavirus (SARS-CoV) 2 antigen using an anti-SARS CoV 2 nucleoprotein (NP) antibody (Sino Biological, 40143-MM05, mouse monoclonal) was performed on sections of brain and lung of all dogs using the Dako EnVision+ polymer system (Dako Agilent Pathology Solutions) and 3, 3'-Diaminobenzidine tetrahydrochloride (Sigma-Aldrich, St.Louis, MO, United States) as described previously ( 23 , 24 ). Investigation of rabies-virus infection was performed in two dogs (case 2 and 3) at the Lower Saxony State Office for Consumer Protection and Food Safety.…”

Viral Vector Vaccine Development and Application during the COVID-19 Pandemic

“…The main administration routes of vaccines include intramuscular, oral and intranasal vaccinations. Omicron mainly causes upper respiratory tract infections while intramuscular vaccines often target lower respiratory tract infections [ 74 ]. Therefore, it is of great significance to develop novel, highly effective intranasal vaccines.…”