MMP9 and infection: In contrast, genes which were unique to a single group demonstrated the greatest activity linked to matrix metalloproteinases (MMPs) as demonstrated by enrichment of the terms mmp, mmp9, metalloproteinases, and matrix (Fig. 1G) driven by MMP9 and ADAMTS4 downregulation in 24 h p.i. samples compared to mock infection and ADAMTS1 upregulation in 24 h p.i. relative to 2 h p.i. (Supplemental Files SF1).