Rescue of nonlytic Newcastle Disease Virus (NDV) expressing IL-15 for cancer immunotherapy.

In order to test and enhance the antitumor activity against mice melanoma by NDV-modified tumor vaccine, a recombinant NDV expressing IL-15 (LX/(IL-15)) was generated by reverse genetics. Then, the expression level and biological activity of IL-15 were examined. Our results showed that mice tumor cell lines infected with LX/(IL-15) expressed IL-15 at a high level, and that expressed IL-15 was biologically active. Expression kinetics demonstrated that the highest expression level of IL-15 was at 48h post infection. The cytotoxicity assay showed that murine melanoma cells modified with LX/(IL-15) could significantly enhance the antitumor immune response in vitro. In vivo study also showed that murine melanoma cells modified with LX/(IL-15) could prevent melanoma growth in mice. Taken together, our data strongly indicated that recombinant LX/(IL-15) is a promising agent for cancer immunotherapy both for human and animal.