Study of SARS-CoV-2 neurotropism

: are SH-SY5Y, U-87 MG and U-373 MG cell lines susceptible towards SARS-CoV-2 infection?

Résumé

The severe acute syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible of the coronavirus disease that emerged in 2019 (COVID-19). Most people suffer from flu-like symptoms such as dry cough or loss of smell subsequently to the infection of the upper respiratory tract. Up to 36% of hospitalized patients develop neurologic symptoms linked to direct or indirect damages to the nervous tissues. It is hypothesized that SARS-CoV-2 could reach the central nervous system via different routes such as axonal transport or hematogenous
route and hence infect various nervous cell types, from neurons to astrocytes, demonstrating its neurotropism. The aim of this master thesis is to model the neuro-invasion on three neural cell lines (SH-SY5Y, U-87 MG and U-373 MG), investigate their susceptibility/permissiveness and to assess the potential cytopathic effects. First, internalization of the virus was demonstrated
using fluorescent in-situ hybridization, confocal microscopy, transmission electron microscopy and qRT-PCR. This viral entry does not seem to be modulated by inflammation (mimicked by TNF-α) despite the fact that the level of expression of various entry genes (ACE2, CD147, NRP1, TMPRSS2, CD26, and furin) was modulated. RT-qPCR was done to assess the expression level of the viral gene E in the culture supernatant at various timings post-infection and chromogenic in-situ hybridization was done to detect the presence of template ssRNA-. This last analysis suggested that the virus could not efficiently replicate in those neural cells and that new viral particles were not massively released in the extracellular environment. Finally, a mild cytopathic effect was observed by shortened neuritic and gliotic processes within 24 hours post-infection. The cytopathic effect did not lead to cell death as no LDH release was quantified in the supernatant of infected SH-SY5Y, U-87 MG and U-373 MG cells. In conclusion, SARS-CoV-2 can be internalized in neuron-like and astrocyte-like cells, but it seems that the replication of the virus is not efficient and might not allow the massive release of new viral particles in the extracellular milieu.

la date de réponse	18 janv. 2022
langue originale	Anglais
L'institution diplômante	Universite de Namur
Superviseur	Charles Nicaise (Promoteur) & Nicolas Gillet (Copromoteur)