CD8A and infection: Notably, the gene expression profile of CD8+ T cells from the PRRSV-infected group showed a significant enrichment in genes upregulated in effector CD8+ T cells at the peak expansion phase (day 8 after LCMV-Armstrong infection) compared to effector CD8+ T cells at the contraction phase (day 15 after LCMV-Armstrong infection), indicating a highly active effector state.