VT-224 is a secreted 43 kDa glycoprotein that is a member of a larger family of poxvirus chemokine binding proteins called the M-T1/35K family that binds specifically to the CC-class of chemokines thereby preventing CC-chemokine receptor stimulation. VT-224 has demonstrated affects on the regulation of infiltrating leukocytes into sites of infection, an ability to disrupt macrophage migration and inhibition of chemotaxis both in vitro and in vivo.

Early in vivo characterization of VT-224 has demonstrated a potent ability to reduce vascular inflammation at low doses (ng-pg) in an aortic allograft transplant model.  VT-224 was active in reducing intimal hyperplasia, monocyte/macrophage and CD2 positive T-cell infiltration into sites of injury.