title: Astrocyte response to Junín virus infection.
abstract: In a previous study of experimental murine encephalitis induced by Junín virus (JV), an arenavirus, we showed increased expression of iNOS by unidentified cells, concomitant with the astrocyte reaction. The specific inhibition of iNOS was associated with greater mortality but lower astrocytosis, suggesting that the protective role of nitric oxide (NO) synthesized by iNOS was related to enhanced astrocyte activation, representing a beneficial cellular response to virus-induced central nervous system damage. In the present work, cultured astrocytes were used to study whether JV infection could trigger iNOS expression and assess its eventual relationship with viral replication, glial fibrilary acidic protein (GFAP) expression levels and the presence of apoptosis. We found that JV infection of astrocytes did not induce apoptosis but produced both increased iNOS synthesis, detected by immunocytochemistry and fluorescence activated cell sorting (FACS) analysis, and increased NO, which was indirectly measured by nitrite/nitrate levels. These changes occurred early relative to the increases in GFAP expression, as detected by immunocytochemistry, FACS analysis and RT-PCR. The fact that iNOS inhibition abolished enhanced GFAP expression in infected monolayers suggests that NO was directly involved. In addition, iNOS inhibition enhanced virus replication. Together with data from confocal microscopy, these results suggest that JV induces iNOS expression in infected astrocytes and that the resulting NO has an important role both in reducing viral replication and in enhancing subsequent astrocyte activation.
authors.affiliation: Thrombosis 1 Laboratory, Haematological Research Institute, National Academy of Medicine, Pacheco de Melo 3081, 1425 Buenos Aires, Argentina.
authors.forename: Roberto G
authors.initials: RG
authors.lastname: Pozner
authors.forename: Soledad
authors.initials: S
authors.lastname: Collado
authors.forename: Carolina
authors.initials: C
authors.lastname: Jaquenod de Giusti
authors.forename: Agustín E
authors.initials: AE
authors.lastname: Ure
authors.forename: Marina E
authors.initials: ME
authors.lastname: Biedma
authors.forename: Victor
authors.initials: V
authors.lastname: Romanowski
authors.forename: Mirta
authors.initials: M
authors.lastname: Schattner
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Gómez
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism* / Q000528:radiation effects / Q000821:virology*; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D002990:Clobetasol / Q000031:analogs & derivatives; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry / Q000379:methods; D015967:Gene Expression Regulation, Viral / Q000187:drug effects / Q000528:radiation effects; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D018051:Junin virus / Q000502:physiology*; D008239:Lysine / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D005904:Glial Fibrillary Acidic Protein; C090663:N(6)-(1-iminoethyl)lysine; C064466:halobetasol; D002990:Clobetasol; D052247:Nitric Oxide Synthase Type II; D008239:Lysine