Because we found similar kinetics of HVEM expression on T cells derived from reovirus-infected tumors as observed during acute vaccinia virus infection,36 and high expression of BTLA on macrophages or CD11c+ DCs within two reovirus-treated tumor models studied, we believe that the HVEM-BTLA trans co-signaling system could be contributing to the functional outcomes of responding T cells and development of the protective immune response observed in the reovirus-treated mice. The gene discussed is BTLA; the disease is neoplasm.