A chimeric oncolytic virus is described that includes a herpesvirus having a modified nucleic acid sequence, including a modification of the herpesvirus gamma (1)34.5 gene (γ.sub.134.5) or a nucleic acid with at least about 70% homology to the γ.sub.134.5 gene that reduces its expression; a second viral nucleic acid sequence encoding a PKR evasion protein that does not cause virulence; and a third nucleic acid sequence encoding a tumor-associated antigen. Methods of using the chimeric oncolytic virus to treat subjects having cancer, or to vaccinate subjects at risk of developing cancer, are also described.

This document relates to methods and materials involved in treating a mammal (e.g., a human) having cancer and/or an infectious disease. For example, this document provides recombinant human cytomegalovirus (hCMV) vectors that include (e.g., are designed to include) nucleic acid encoding a viral gene transfer vector genome (e.g., a heterologous viral gene transfer vector genome) and one or more nucleic acids encoding a packaging polypeptide such that a cell of a mammal that is infected with the hCMV vector can produce and release the viral vector (e.g., an infectious lentiviral vector) which can then infect cells (e.g., immune cells) in vivo and can, optionally, drive expression of an exogenous polypeptide (e.g., a therapeutic polypeptide or an antigen receptor such as a chimeric antigen receptor (CAR)) in the infected immune cells within a mammal (e.g., a human) to induce an immune response within the mammal are provided.