The present invention is directed to mammalian bi-specific T cells and methods for using these bi-specific T cells. More specifically, the invention relates to a method of controlling administration of cancer antigen to a subject by providing bi-specific T cells that express a viral antigen T cell receptor and a cancer antigen-specific chimeric receptors and triggering their activation by also administering antigen-presenting T-cells which express viral antigen. These bi-specific T cell clones are a source of effector cells that persist in vivo in response to stimulation with viral antigen, leading to long-term function after their transfer to patients with cancer and autoimmune diseases.