Intermediate filament integrity is required for Junin virus replication

The role of the cytoskeletal framework in Junin virus (JUNV) replication has already been demonstrated with compounds interfering with the microfilament (MF) and microtubule (MT) networks. In this work, we evaluated the role of intermediate filaments (IF) during JUNV infection. We tested the effect of acrylamide, a compound that selectively disrupts IF, in culture of three different cell types: Vero cells, murine astrocytes and human foreskin fibroblasts. Perturbation of intermediate filaments had an inhibitory effect on JUNV production within a range of acrylamide concentration of 0.5–3 mM in a dose-dependent manner, without cell viability modification. Recovery experiments showed that viral production was partially increased when medium containing acrylamide was replaced by normal maintenance medium (MM). The adsorption and internalization steps were not affected by IF disruption. The expression of JUNV proteins was highly reduced in the presence of 2 mM acrylamide while immunofluorescence staining of IF showed network disruption with the formation of cytoplasmic aggregates containing vimentin or glial fibrillary acidic protein (GFAP). We conclude that the IF network may play a role in the early step of JUNV multiplication, subsequent to virus entry and that its integrity is a necessary condition for the normal replication of JUNV in neural and fibroblast cells as well as in the Vero cell line.