Abstract: Provided is a novel vector for immunostimulation and methods of using same in immunotherapy, in particular cancer immunotherapy. The novel vector comprises nucleic acid sequences encoding 4-1BB ligand (4-1BBL, CD137 ligand), single chain IL-12 (sc IL-12) and IL-2, wherein the vector provides for an increased expression of 4-1BBL as compared to the expression levels of sc IL-12 and IL-2. Specifically, the nucleic acid sequences encoding 4-1BBL, sc IL-12 and IL-2 are organized in the vector in 5? to 3? orientation in a sequential order 1, 2, 3, with the proviso that the gene encoding sc IL-12 is not at position 1. Embodiments of the present disclosure include virus particles comprising the novel vector as well as cancer or immune cells transduced or transfected with the novel vector.