Retroviral vector having immune-stimulating activity

A recombinant replication competent retroviral vector comprising a sequence encoding at least one agent that down regulates an immune inhibitory agent, wherein the at least one agent is a sequence encoding an antibody to a programmed death ligand (PDL) wherein the replication competent retroviral vector has a genome of the general structure from 5′ to 3′ comprising a long terminal repeat (LTR)-gag sequence-pol sequence-env sequence-at least one expression cassette-LTR, wherein said recombinant retroviral vector comprises a first cassette comprising a polIII promoter operably linked to a first inhibitory nucleic acid sequence, and a second cassette comprising a mini-promoter operably linked to the sequence encoding the antibody to the PDL.