Hamster organotypic modeling of SARS-CoV-2 lung and brainstem infection

Abstract

SARS-CoV-2 has caused a global pandemic of COVID-19 since its emergence in December 2019. The infection causes a severe acute respiratory syndrome and may also spread to central nervous system leading to neurological sequelae. We have developed and characterized two new organotypic cultures from hamster brainstem and lung tissues that offer a unique opportunity to study the early steps of viral infection and screening antivirals. These models are not dedicated to investigate how the virus reaches the brain. However, they allow validating the early tropism of the virus in the lungs and demonstrating that SARS-CoV-2 could infect the brainstem and the cerebellum, mainly by targeting granular neurons. Viral infection induces specific interferon and innate immune responses with patterns specific to each organ, along with cell death by apoptosis, necroptosis, and pyroptosis. Overall, our data illustrate the potential of rapid modeling of complex tissue-level interactions during infection by a newly emerged virus.

Non-Productive Infection of Glial Cells with SARS-CoV-2 in Hamster Organotypic Cerebellar Slice Cultures

“…Contrary to some other studies that have modelled SARS-CoV-2 infection in cultured human brain organoids [42][43][44] and a recent study that also used hamster brain slices [45], we failed to find evidence of neuronal infection in organotypic brain sections. Cultured organoids differ from mature brain tissue and organotypic sections in several ways, most markedly in the relative immaturity of cells and the lack of immune cells and vasculature.…”

“…It is possible that receptors expressed by immature neurons not present in our cultured slices support infection with SARS-CoV-2 explain these differences. Viral infection was reported in brainstem organotypic slices by Ferren et al [45] specifically in granular neuronal subtypes (Golgi type 1). The biological differences in subpopulations of cells within the slices and the culture conditions may explain the discrepancies between our observations and this study.…”

SARS-CoV-2 infection in hamsters and humans results in lasting and unique systemic perturbations after recovery

“…This phenomenon can also be modeled in the golden hamster, one of the most widely used small animal models for COVID-19, which demonstrates consistent infection of the respiratory tract and olfactory epithelium upon intranasal challenge, with only sporadic isolation of virus from other tissues unless IFN-I biology is disrupted ( 20 – 24 ). This finding is further supported by the fact that SARS-CoV-2 has been seen to readily infect ex vivo organotypic cultures of hamster brain tissues, which are not readily seen to be sites of viral replication in intranasal infection conditions ( 21 , 25 ). This same phenomenon can be observed when infected individuals are immunosuppressed ( 17 , 26 – 28 ).…”

The neuroinvasiveness, neurotropism, and neurovirulence of SARS-CoV-2

“…In humans, autopsies revealed SARS-CoV-2 antigens in the brain parenchyma and cortical neurons of some patients, while SARS-CoV-2 viral RNA has been detected in the substantia nigra [16,29]. Additionally, animal studies suggest that dopaminergic neurons and, to a lesser extent, cortical neurons, microglia, and astrocytes are susceptible to SARS-CoV-2 infection [29,45,46]. Human pluripotent stem cell (hPSC)-derived 2D cultures and 3D organoids (models reviewed in [47]) have been used to investigate the cell tropism of SARS-CoV-2 in vitro [48].…”