A novel polypeptide ligand, p30, or LIGHT, for herpes virus entry mediator,HVEM, is provided. p30 is useful for modulating immune responses and ininhibiting infection and/or subsequent proliferation by herpes virus. HVEMfusion proteins are also provided. Methods for treating subjects with lymphoidcell disorders, tumors, autoimmune diseases, inflammatory disorders of thosehaving or suspected of having a herpes virus infection, utilizing p30 and thefusion proteins of the invention, are also provided.
