PARTICIPATION OF CYTOPLASMIC SILENCING BODIES IN JUNIN VIRUS REPLICATION.

LINERO, FLORENCIA; THOMAS, MARÍA GABRIELA; BOCCACCIO, GRACIELA; SCOLARO, LUIS

Montana State University

Congreso; 29th Annual Meeting, The American Society for Virology; 2010

The American Society for Virology

Viruses use different approaches to improve replication strategies manipulating host cytoplasmic RNA structures such as stress granules (SGs) and processing bodies (PBs). In this work we evaluated, in first place, if infection of Vero cells with the arenavirus Junin (JUNV), etiological agent of the Argentine Hemorrhagic Fever induces SGs and PBs formation. On this purpose, Vero cells were infected with JUNV at an MOI of 1 pfu/cell, and processed at 24 and 48 h p.i. for indirect immunofluorescence assay (IFA) using SGs markers: TIA-1and PABP-1, PBs marker: Hedls and eIF4E common marker for both structures . We observed that JUNV infection did not induce the formation of SGs and PBs neither promoted nuclei-cytoplasm translocation of PABP-1 and TIA-1 markers. Then, we analyzed if JUNV interferes with SGs and PBs formation induced by sodium arsenite. Vero cells infected with JUNV were treated with 500ìM sodium arsenite during 1 h before processing for IFA. We observed a reduction in the formation of SGs in cells bearing viral antigens (viral nucleoprotein, N, and main glycoprotein, G1) reaching 60-80% of inhibition at 48 h p.i.. PBs formation was not affected by infection. Eukaryotic cells respond to stress conditions, including viral infection, in part by down modulating the overall rate of protein synthesis. This translational control response to stress occurs largely through phosphorylation of eIF2alpha, by specific cellular serine-threonine protein kinases. In view of this fact, we analyzed if the impairment in SGs formation induced by JUNV would be associated to the inhibition of eIF2alpha phosphorylation. JUNV infected Vero cells at an MOI of 1 pfu/cell, treated with sodium arsenite 1 h before processing at 16, 24 and 48 h p.i. were subjected to western blot assay using an anti-phospho eIF2alpha antibody. No phosphorylation of eIF2alpha could be detected only at 48 h p.i suggesting that the impairment of SGs formation might be due to the inhibition of the phosphorylation of this factor. These results suggest that JUNV infection is able to regulate the stress response of the cells impairing SGs formation in order to recruit factors associated to these granules to improve its replication efficiency.