RAX deficiency causes failure of host antiviral defense to VSV infection. (A) Viability of MEF cell lines, as measured by trypan blue dye exclusion, 24 hours after infection with VSV at the indicated multiplicity of infection (MOI). (B) The increase in PKR autophosphorylation activity relative to total PKR level after the indicated time of infection with VSV at an MOI of 1 was determined by densitometry analysis of autoradiographs and Western blots from 3 separate experiments as described and graphed. (C) Densitometry analysis of Western blots from 3 separate experiments using antibodies specific for eIF2α and phosphoserine-51 eIF2α was used to determine and graph the fold increase in phospho-eIF2α relative to total eIF2α at the indicated times after VSV infection at an MOI of 1. (D) Western blotting with antibody R1 was used to monitor viral protein production of N, P, and M proteins at the indicated times after infection. (E) Virus titers of supernatants from infected cells 24 hours after infection were measured by plaque assay using BHK-21 cells. pfu indicates plaque-forming unit.