A previously published study from our laboratory however, reported down-regulation of IL-12p40, IL-8, IL–1β, and CCL-20 mRNA in tracheal tissues at day-1 post-infection, whereas chemokines like MIP-1β, CXCL-13, RANTES and lymphotactin were found to be up-regulated [12]. This evidence concerns the gene CCL4 and infection.