The vaccinia virus soluble interferon-γ receptor is a homodimer

The vaccinia virus (VV) interferon (IFN)-gamma receptor (IFN-gammaR) is a 43 kDa soluble glycoprotein that is secreted from infected cells early during infection. Here we demonstrate that the IFN-gammaR from VV, cowpox virus and camelpox virus exists naturally as a homodimer, whereas the cellular IFN-gammaR dimerizes 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.