A human cell line, which lacks major histocompatibility class I (MHC-I) antigens and major histocompatibility class II (MHC-II) antigens and which has been modified to comprise and express (i) a nucleotide sequence encoding an immunomodulator and (ii) a nucleotide sequence encoding a viral antigen, and a method of inducing or stimulating an immune response in a human to a viral-associated disease or cancer comprising administering to the human (i) the aforementioned human cell line in an amount sufficient to induce or stimulate an immune response to the viral associated disease or cancer, (ii) a human cell line, which lacks MHC-I and MHC-11 antigens and which has been modified to comprise and express a nucleotide sequence encoding an immunomodulator, and a human cell line, which lacks MHC-I and MHC-II antigens and which has been modified to comprise and express a nucleotide sequence encoding an antigen of EBV, simultaneously or sequentially in either order, by the same or different routes, in amounts sufficient to induce or stimulate an immune response to the viral-associated disease or cancer, or (iii) an immunomodulator and a human cell line, which lacks MHC-I and MHC-II antigens and which has been modified to comprise and express a nucleotide sequence encoding an antigen of EBV, simultaneously or sequentially in either order, by the same or different routes, in amounts sufficient to induce or stimulate an immune response to the viral associated disease or cancer.