A human synovial fibroblast cell line acutely infected with RRV in vitro demonstrated upregulation in monocyte chemoattractant protein-1 (MCP-1) mRNA expression [81,82], which, in turn, will cause monocytes to egress from the bone marrow and migrate into tissues, followed by maturation into macrophages at the site of infection. Here, CCL2 is linked to infection.