An additional phenotype linked to host shutoff caused by muSOX and its homologs is the relocalization of cytoplasmic poly(A) binding protein (PABPC) into the nuclei of infected cells [24] . We observed clear nuclear relocalization of PABPC in cells infected with MHV68.WT, whereas in mock infected or cells infected with MHV68.DHS, PABPC remained cytoplasmic ( Figure 3E ). Thus, cells were transfected with a plasmid expressing GFP alone or together with a plasmid expressing HA-tagged wild-type (wt) muSOX or muSOX R443I. GFP fluorescence was monitored 24 h post transfection, along with HA-muSOX, which was detected by immunofluorescence with anti-HA antibodies. Samples were co-stained with DAPI to visualize nuclei. (C) Cells were transfected for 24 h as described above, whereupon GFP mRNA and 18S rRNA levels were analyzed by Northern blot. Shown is a representative northern blot for GFP mRNA and 18S rRNA, and below is the normalized data from five independent experiments with means and standard deviations shown. (D) Total protein was harvested 24 h post transfection with the indicated plasmids, and Western blotted with anti-HA antibodies. The bottom band present in all samples is due to non-specific binding of the antibody. (E) In vitro translated GFP, wild-type muSOX, or muSOX-R443I was incubated with linear DNA for the indicated times. DNA was then extracted and separated by agarose gel electrophoresis. A representative figure from three independent experiments is shown. doi:10.1371/journal.ppat.1002150.g001 MHV68.DHS is defective for two hallmarks of host shutoff, mRNA depletion and PABPC relocalization. These results also demonstrate for the first time that muSOX-induced host shutoff is necessary to drive PABPC relocalization during a viral infection.