CCL4 and infection: To determine whether the early inflammatory response elicited by HN878 infection at 3 hours is localized to the lungs or whether it is systemic, we analyzed the expression of 12 selected SDEG, including cytokines and chemokines (TNF, IL18, IL1A, SPP1, CCL2, CCL4, CXCL10, TGFB2, IL4R, CAV1, CD36 and IRF5), by qRT-PCR using total RNA from the blood leukocytes of HN878-infected rabbits at 3 hours, compared to uninfected animals (Additional file 4: Table S5).