Investigating the Syrian hamster as model for SARS-CoV-2 infection

The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the necessity to dispose of proper tools and models to investigate the pathophysiology of potential new pandemic threats and to validate effective therapeutical protocols. To shed light on the extensively used but controversial model Syrian hamster, we investigated males and females response to SARS-CoV-2 infection, analyzing several target organs from an histopathological and transcriptomic point of view. Both males and females hamsters are responsive to SARS-CoV-2 infection, developing important pulmonary lesions, inflammation and immune system recruitment that was evident from lungs and PBMCs transcriptome profiles. Brains and intestines are infected by the virus, and both males and females rapidly respond to the infection promoting viral elimination; therefore, no lesions have been found in all the tested subjects. Interestingly, Syrian hamsters rapidly recover lung lesions in a fourteen days period, an observation that underlines their distance from COVID-19 pathology in humans. Of note, we found that only males subjects promote high expression of several pro-inflammatory cytokines and active neutrophils genes in the lungs at the infection peak, and the same result was obtained analyzing PBMCs transcriptome. All this evidence demonstrates that the Syrian hamster represents a good model to mimic and treat moderate COVID-19, with males subject being more inclined to develop a systemic pathology