Theiler’s murine encephalomyelitis virus replicates in primary neuron cultures and impairs spine density formation

TOMATIS, C; LEON, ANTONELLA; AÍDA O LÓPEZ ORTIZ; PAULA ONETO; FEDERICO FUENTES; MARÍA F FERRER; EUGENIO A CARRERA SILVA; CAMILA SCORTICATI; RICARDO GOMEZ

NEUROSCIENCE

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2023

0306-4522

Theiler´s murine encephalomyelitis virus (TMEV) can cause acute fulminant or persistent centralnervous system infection, axonal demyelination, autoimmunity, and an epilepsy-like syndrome,depending on the viral strain. These later strains encode a protein outside the framework of thepolyprotein that plays a key role in these diseases.In this study, we examined infection with the GDVII and DA strains and with a mutant DA, whichlacks the L* protein (L*-1), to analyze the direct effects of TMEV replication using primarycultures of mouse brain hippocampal neurons. All viruses replicate in cultured neurons, withGDVII having the highest titers and L*-1 the lowest. Accordingly, all were positive for viralantigen staining 3 days postinfection (dpi), and DA and L*-1 were also positive after 12 dpi.NeuN+ immunostaining showed an early and almost complete absence of positive cells incultures infected with GDVII, an approximately 50% reduction in cultures infected with DA, andno changes in L*-1 strains after 3 dpi. Accordingly, staining withchloromethyltetramethylrosamine orange (Mitotracker OrangeTM) as a parameter for cellviability showed similar results. Moreover, the strain DA induced higher transcription levels ofneuroprotective genes such as IFN-Iβ, IRF7 and IRF8 at 24 hpi. At 3 dpi, strains GDVII and DA,but not the L*-1 mutant showed lower PKR expression. In addition, confocal analysis showedthat L*-1-infected neurons exhibited a decrease in spine density. Treatment with poly (I:C),which was used to simulate viral infection, reduced spine density even more. These resultsvalidated the use of mouse hippocampal neuron cultures as a model to study neuronalresponses after TMEV infection.