To quantify RNA, we isolated RNA from transfected cells using RNA-Bee (Tel-Test) or the Zymo Mini RNA II Isolation Kit (Zymo Research). Samples were treated with Turbo DNase (Ambion) according to the manufacturer's protocol to remove genomic DNA contamination. To generate cDNA, RNA samples were reverse transcribed using AMV RT (Promega) and an oligo dT or 18Sspecific primer. 18S rRNA or GAPDH mRNA levels were quantified using TaqMan ribosomal RNA control reagents or TaqMan rodent GAPDH control reagents (Applied Biosystems). Other endogenous mRNA levels were quantified using Applied Biosystems Taqman Gene Expression Assays (actB-Mm01205647_g1, rplp2-Mm03059047_gH, tubb5-Mm00495806_g1). To quantify viral genomes, DNA was first isolated from spleen cells or cervical lymph node cells by the Qiagen QIAamp DNA Mini Kit following the manufacturer's protocol. Viral DNA levels were then measured using a previously described assay targeting the MHV68 ORF8 gene [35] . All qPCR reactions were performed with TaqMan Universal PCR Master Mix.