Abstract: Objective In this study, we investigated the therapeutic antitumor effect of recombinant Ankara virus encoding murine CD40L(TBC-MVA-mCD40L)in a murine B-cell lymphoma model.Methods After infection in vitro and in vivo, costimulatory molecules CD80 and CD86 expressions of A20 cells were assessed by flow cytometry.BALB/c mice with established s.c.and widely metastatic A20 lymphoma tumors were treated with intratumoral injections of TBC-MVA-mCD40L together with systemic chemotherapy.Next the BALB/c mice were vaccinated with irradiated A20 cells transduced with TBC-MVA-mCD40L before rechallenged with A20 and another CT26 cell line.We observed direct antitumor effect and prophylactic antitumor protection effect of TBC-MVA-mCD40L by measuring the tumor size of lymphoma model(A20)in BALB/c mice.Results Some tumor cells in the injected sites expressed the CD40L transgene, and had increased expressions of the CD80 and CD86 costimulatory molecules.The combined chemoimmunotherapy resulted in complete tumor regression and long-term survival of the mice.Otherwize, mice vaccinated with irradiated A20 cells transduced with TBC-MVA-mCD40L are protected against A20 tumor cells.Conclusion These Results show that genetic modification of tumor B cells with CD40L can be a useful strategy to promote systemic immunity against B-cell malignancies.The Results support future plans for intratumoral injection of TBC-MVA-mCD40L in patients with lymphoma.