title: Astrocyte response to St. Louis encephalitis virus.
abstract: St. Louis encephalitis virus (SLEV), a flavivirus transmitted to humans by Culex mosquitoes, causes clinical symptoms ranging from acute febrile disorder to encephalitis. To reach the central nervous system (CNS) from circulating blood, the pathogen must cross the blood-brain barrier formed by endothelial cells and astrocytes. Because astrocytes play an essential role in CNS homeostasis, in this study these cells were infected with SLEV and investigated for astrogliosis, major histocompatibility complex (MHC)-I-dependent immune response, and apoptosis by caspase-3 activation. Cultures of Vero cells were used as a positive control for the viral infection. Cytopathic effects were observed in both types of cell cultures, and the cytotoxicity levels of the two were compared. Astrocytes infected with a dilution of 1E-01 (7.7E+08 PFU/mL) had a reduced mortality rate of more than 50% compared to the Vero cells. In addition, the astrocytes responded to the flavivirus infection with increased MHC-I expression and astrogliosis, characterized by intense glial fibrillary acidic protein expression and an increase in the number and length of cytoplasmic processes. When the astrocytes were exposed to higher viral concentrations, a proportional increase in caspase-3 expression was observed, as well as nuclear membrane destruction. SLEV immunostaining revealed a perinuclear location of the virus during the replication process. Together, these results suggest that mechanisms other than SLEV infection in astrocytes must be associated with the development of the neuroinvasive form of the disease.
authors.affiliation: Institute of Bioscience, Federal University of Uberlandia, Para 1720, Uberlandia, Minas Gerais CEP 38400-902, Brazil.
authors.forename: Adriano Lara
authors.initials: AL
authors.lastname: Zuza
authors.affiliation: Institute of Bioscience, Federal University of Uberlandia, Para 1720, Uberlandia, Minas Gerais CEP 38400-902, Brazil.
authors.forename: Heber Leão Silva
authors.initials: HL
authors.lastname: Barros
authors.affiliation: Institute of Bioscience, Federal University of Uberlandia, Para 1720, Uberlandia, Minas Gerais CEP 38400-902, Brazil.
authors.forename: Thelma Fátima
authors.initials: TF
authors.lastname: de Mattos Silva Oliveira
authors.affiliation: School of Medicine, Federal University of Mato Grosso, MT 270 St., Km 06, Rondonopolis, Mato Grosso, Brazil.
authors.forename: Juliana Helena
authors.initials: JH
authors.lastname: Chávez-Pavoni
authors.affiliation: Institute of Bioscience, Federal University of Uberlandia, Para 1720, Uberlandia, Minas Gerais CEP 38400-902, Brazil. Electronic address: rezanon@yahoo.com.br.
authors.forename: Renata Graciele
authors.initials: RG
authors.lastname: Zanon
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000821:virology*; D016923:Cell Death; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004665:Encephalitis Virus, St. Louis / Q000502:physiology*; D051379:Mice; D014709:Vero Cells
keywords: Astrocytes; Flavivirus infections; Glial fibrillary acidic protein; St. Louis encephalitis virus