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Authors:Osterrieder et al. 

Journal/ Pre-Print:bioRxiv 

Tags: Cell Biology, Immunology/Immunity, Inflammation 

Research Highlights 

1. Syrian hamsters are a useful model for observing age-dependent differences in SARS-CoV2 infection.  

2. SARS-CoV2 infected aged Syrian hamsters had a greater body weight loss than young Syrian hamsters whereas viral loads were similar 

3. Young hamsters had more robust early lung inflammation and exhibited recovery by d14 whereas older animals had early oedema and unresolved inflammation at d14 

Summary 

Young (6 weeks) and aged (32-34 weeksSyrian hamsters were intranasally infected with SARS-CoV2 or mock-infected Aged animals experienced greater body weight loss compared to young. Viral load was similar between the groups and virus was mostly cleared from the lungs by d14. Histopathological features of infection were assessed over time. Young animals had more leukocyte infiltrates at the onset compared to older, which in turn had increased swelling. Lung tissues had almost recovered in young hamsters at day 14, while the aged still had persistent inflammation and lung damage. 

Impact for SARS-CoV2/COVID19 research efforts  

Others: Describes new model for evaluating vaccines and therapies against SARS-CoV2/COVID19 

  • This study evaluates the age-dependent differences of SARS-CoV2 infection is Syrian hamsters and demonstrates the presence of clinical markers of infection in the hamsters, such as body weight loss, thus providing a potentially useful model for evaluating efficacy of antivirals and vaccinations in young and aged animals  

Study Type  

  • In vivo study (e.g. mouse, NHP) 

Strengths and limitations of the paper 

Novelty:  

  • This study describes the differences in SARS-CoV2 infection in young compared to aged Syrian hamsters. It finds that body weight loss is a robust clinical marker of infectionand that there are histopathological differences between young and aged hamsters. The study highlights the Syrian hamster as a useful model for evaluating therapies and vaccinations while considering age-dependent differences. 

Standing in the field: 

  • Previous research suggests that hamsters are highly susceptible to SARS-CoV2 infection, and that young male hamsters tend to experience relatively mild disease. This is the first study to evaluate the age-related differences of SARS-CoV2 infection in Syrian hamsters.  

Appropriate statistics: 

  • No statistical analysis of data, making it difficult to evaluate significance of differences described. 

Viral model used: 

  • 1x10PFU of SARS-CoV2 München (BetaCoV/Germany/BavPat1/2020)  

Translatability: 

  • Potential for pre-clinical assessments of SARS-CoV2 vaccines and therapies. Further investigation into the immune response of Syrian hamsters to SARS-CoV2 infection is needed.  

Main limitations:  

  • Sample size for day 7 and 14, when the differences between young and aged arise, is only one and two, respectively.  

  • A more thorough look at immune responses to SARS-CoV2 infection in Syrian hamsters would have been useful. The authors mention age-dependent differences in antibody titres and further exploration of this would have been useful.  

  • Some of the conclusions the authors have made aren’t entirely supported by their data. The authors suggest that body weight loss “provides an objective way to judge clinical efficacy of antiviral therapy or vaccination”, however this is based on no significance testing and a relatively small sample size of n=12 per group. This claim needs further validation before body weight loss can be used as a reliable marker of clinical efficacy.