Pulmonary lesions following inoculation with the SARS-CoV-2 Omicron BA.1 (B.1.1.529) variant in Syrian golden hamsters. Issue 1 (31st December 2022)

• Record Type: Journal Article
• Authors: Rissmann, Melanie; Noack, Danny; van Riel, Debby; Schmitz, Katharina S.; de Vries, Rory D.; van Run, Peter; Lamers, Mart M.; Geurts van Kessel, Corine H.; Koopmans, Marion P. G.; Fouchier, Ron A. M.; Kuiken, Thijs; Haagmans, Bart L.; Rockx, Barry
• Is Part Of: Emerging microbes & infections. Volume 11:Issue 1(2022)
• Page Start: 1778
• Page End: 1786
• Publication Date: 2022-12-31
• Subjects: SARS-CoV-2 -- Omicron BA.1 -- Delta -- Syrian golden hamster -- pathology -- re-challenge -- pre-existing immunity; Medical microbiology -- Periodicals; Communicable diseases -- Periodicals; Infection -- Periodicals; 616.9041
• DOI: 10.1080/22221751.2022.2095932
• Languages: English
• ISSNs: 2222-1751

Abstract

ABSTRACT: The Omicron BA.1 (B.1.1.529) SARS-CoV-2 variant is characterized by a high number of mutations in the viral genome, associated with immune escape and increased viral spread. It remains unclear whether milder COVID-19 disease progression observed after infection with Omicron BA.1 in humans is due to reduced pathogenicity of the virus or due to pre-existing immunity from vaccination or previous infection. Here, we inoculated hamsters with Omicron BA.1 to evaluate pathogenicity and kinetics of viral shedding, compared to Delta (B.1.617.2) and to animals re-challenged with Omicron BA.1 after previous SARS-CoV-2 614G infection. Omicron BA.1 infected animals showed reduced clinical signs, pathological changes, and viral shedding, compared to Delta-infected animals, but still showed gross- and histopathological evidence of pneumonia. Pre-existing immunity reduced viral shedding and protected against pneumonia. Our data indicate that the observed decrease of disease severity is in part due to intrinsic properties of the Omicron BA.1 variant.