VT-384 (IL-18bp) is a novel secreted glycoprotein recently identified in a primate poxvirus.   Primate poxviruses have evolved to subvert the primate (human) immune system in part through the development of potent anti-inflammatory compounds.  VT-384 has been found to bind with high affinity to the human pro-inflammatory cytokine IL-18. Poxviruses have clearly borrowed from the body's attempt to regulate IL-18 activity by encoding their own version of a secreted IL-18 binding protein.

Biacore optical biosensor technology has been used to characterize binding to both human and murine IL-18 (Kd of 16 nM and 3.5 nM respectively). In addition cell-based assays have demonstrated that VT-384 was able to prevent the IL-18 stimulated induction of IFN-γ indicating an ability to interfere with IL-18 interactions with cell-surface receptors.

Preliminary pre-clinical data also demonstrates VT-384's potent in vivo anti-inflammatory effects in an inflammatory model of vascular inflammation.