Orf virus-encoded chemokine-binding protein is a potent inhibitor of inflammatory monocyte recruitment in a mouse skin model.

The parapoxvirus orf virus causes pustular dermatitis in sheep and is transmissible to humans. The virus encodes a secreted chemokine-binding protein (CBP). We examined the ability of this protein to inhibit migration of murine monocytes in response to CC inflammatory chemokines, using chemotaxis assays, and its effects on monocyte recruitment into the skin, using a mouse model in which inflammation was induced with bacterial lipopolysaccharide. CBP was shown to bind murine chemokines CCL2, CCL3 and CCL5 with high affinity by surface plasmon resonance and it completely inhibited chemokine-induced migration of monocytes at a CBP:chemokine molar ratio of 4:1. In the mouse, low levels of CBP potently inhibited the recruitment of Gr-1+/CD11b+ monocytes to the site of inflammation in the skin but had little effect on neutrophil recruitment, suggesting that this factor plays a role in disrupting chemokine-induced recruitment of specific immune cell types to infection sites.