The microarray experiment was performed under contact by Kangcheng Co. Ltd. (Shanghai, China). Briefly, total RNA was isolated by Trizol from liver tissue of PD-1-deficient and WT mice treated with 10 PFU MHV-3 for 72 h. RNA concentration was measured on the ND-1000 spectrophotometer (Nanodrop, Wilmington, DE, USA) and quality evaluated by denaturing gel electrophoresis. Samples were then amplified and labeled using a NimbleGen One-Color DNA Labeling Kit and hybridized using the NimbleGen Hybridization System (Roche Applied Science, Shanghai, China). After hybridization and washing, the processed slides were scanned by the Axon GenePix 4000B microarray scanner. Three independent experiments were performed, and for each test and control sample, two hybridizations were carried out by a reverse fluorescent strategy. Only genes whose alteration tendency was concordant between both microarray assays were selected as differentially expressed genes.