Inhibits IFN-gamma synthesis. Down-regulates the expression of the host TAP1 gene (transporter associated with antigen processing), thereby affecting the transport of peptides into the endoplasmic reticulum and subsequent peptide loading by MHC class I molecules. In consequence, infected cells are masked for immune recognition by cytotoxic T-lymphocytes (By similarity). Homodimer. Belongs to the IL-10 family. Be careful of the possible confusion between BCRF1 with BcRF1.