Unraveling the neurotropic potential of SARS-CoV-2 and Oropouche viruses using in vitro and ex vivo models of the human central nervous system

Author(s)

Glaucia Maria de Almeida

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2025-04-01

Examining board members

Adriano Silva Sebollela; Patricia Cristina Baleeiro Beltrao Braga; Felipe Roberti Teixeira

• Advisor: Adriano Silva Sebollela; Eurico de Arruda Neto

Abstract

Neurotropic viruses can cause nervous system diseases, such as encephalitis and meningitis. In recent years, cases of infections by SARS-CoV-2 and Oropouche (OROV) associated with neurological complications have been reported. Furthermore, evidence of the presence of the SARS-CoV-2 genome in the brains of individuals who died from COVID-19, and of the OROV genome in the cerebrospinal fluid of individuals with Oropouche Fever has been described, suggesting that these viruses can invade the central nervous system (CNS). However, the ability of SARS-CoV-2 and OROV to infect CNS cells, as well as the neuropathological alterations resulting from these potential infections, have not yet been well established. In this work, we investigated susceptibility, permissiveness, cell tropism and neurovirulence of these viruses in CNS models, including ex vivo human brain slices cultures. The results demonstrated that SARS-CoV-2 preferentially infects astrocytes and induces a pro-inflammatory response with increased expression of the cytokines IL-6, IL-8 and TGF-β. We confirmed the susceptibility of human brain slices to OROV infection, and using expansion microscopy, an innovative super-resolution technique, we visualized in detail the distribution of viral antigens in the cytoplasm of infected cells. Using a human microglial lineage, we confirmed the susceptibility and permissiveness of these cells to OROV infection, previously shown by our group in tissue culture. Furthermore, OROV infection in human brain slices induced a pro-inflammatory response with increased markers of microglial activation and levels of phosphorylated Tau, a marker of neurodegeneration. We compared the neurotropic potential of OROV with that of herpes simplex virus type 1 (HSV-1), a major cause of encephalitis in adults. We observed that the susceptibility of human brain slices to OROV and HSV-1 infection, as well as their replicative capacities, are similar. Both OROV and HSV-1 were able to induce a strong pro-inflammatory response, indicated by increased levels of TNF-α and IL-1β. Our results robustly demonstrate the potential for infection and tissue damage of SARS-CoV-2 and OROV in the human CNS and reinforce the relevance of using experimental models derived from the adult human brain to study the impact of viral infections on the mature CNS. (AU)

• FAPESP's process: 21/12263-2 - Tissue-molecular alterations associated with viral infections in adult human brain slice cultures
• Grantee: Glaucia Maria de Almeida
• Support Opportunities: Scholarships in Brazil - Doctorate