The vacciniavirus interferon (IFN)-gamma receptor (IFN-gammaR), which is a 43 kDa soluble glycoprotein that is secreted from infected cells early during infection. IFN-gammaR from vaccinia virus, cowpox virus and camelpox virus exist naturally as homodimers, whereas the cellular IFN-gammaR dimerises only upon binding the homodimeric IFN-gamma. The existence of the virus protein as a dimer in the absence of ligand may provide an advantage to the virus in efficient binding and inhibition of IFN-gamma in solution.