Mammalian orthoreovirus infection is enhanced in cells pre-treated with sodium arsenite

Michael M. Lutz; Megan P. Worth; Meleana M. Hinchman; John S. L. Parker; Emily D. Ledgerwood

The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/555367 doi: bioRxiv preprint many tissues and, when activated by sodium arsenite, phosphorylates eIF2α and 323 subsequently induces stress granule formation [27] . HRI is the only stress kinase required 324 for translational inhibition in response to arsenite treatment in mouse embryonic 325 fibroblasts [27] . HRI kinase can also be activated by other cellular stresses including 326 osmotic stress and heat shock. To further assess if the enhanced reovirus infectivity 327 following sodium arsenite treatment was a consequence of HRI activation, we assessed 328 viral protein expression, the percentage of infected cells and viral yield in response to 329 heat shock. We used stress granule induction in response to heat shock as an indirect 330 measure of HRI activation ( Figure 4A ). Our attempts to induce stress granules in CV-1 331 cells with heat shock were only able to achieve no greater than 25% of cells containing 332 stress granules. Because of this, we assessed the effects of heat shock induction of stress 333 granules in L929 cells. Heat shock for 45 minutes at 44°C resulted in ~88% of L cells 334 containing stress granules ( Figure 4A ). Similar to our observations in CV-1 cells pre-335 treated with sodium arsenite, viral protein expression was enhanced at 10 and 18 h p.i. in 336 L cells exposed to a 45 min heat shock prior to infection ( Figure 4B ). However, heat 337 shock activation had no impact on the percentage of infected cells or viral yield in L cells 338 ( Figures 4C-E) . These findings suggest that in L-cells, heat shock enhances protein 339 expression, but does not affect either the numbers of infected cells or the per cell yield of 340 virus. Although heat shock activates HRI kinase, its effect on cells differs from sodium 341 arsenite. Together, these data indicate that sodium arsenite pre-treatment perturbs the cell 342 in a way that is beneficial for reovirus compared to other activators of the HRI kinase. 343 344 All rights reserved. No reuse allowed without permission.