IFNB1 and infection: Since the amount of tissue recovered from swollen paws was variable, we examined normalized gene expression for several Unfolded Protein Response (UPR) genes (Hspa5/BiP, Ddit3/CHOP, and spliced Xbp1 [marker of active UPR]) and UPR-regulated cytokines (Tnf, Ifnb1, and Il23a) to gauge relative degree of infection.