CD40L-adjuvanted DNA vaccine carrying EBV-LMP2 antigen enhances anti-tumor effect in NPC transplantation tumor animal

CD40L, a costimulatory molecule for dendritic cells (DCs) and B cells, can serve as an adjuvant for enhancing the specific immune response induced by DNA vaccine carrying tumor-associated antigens. In this study, we investigated the potential of CD40L as an adjuvant to enhance the anti-tumor effect mediated by a DNA vaccine based on the Epstein-Barr virus-latent membrane protein 2 (EBV-LMP2) antigen. The plasmids capable of expressing the fusion protein EBV-LMP2-CD40L were constructed. Expression vector pVAX1 and plasmid expressing the individual antigen EBV-LMP2 were used as control groups. These plasmids were used to immunize female BALB/c mice (4-6 weeks old) at days 0, 7 and 14. The results suggest that immunization with DNA vaccines carrying fusion gene EBV-LMP2-CD40L can induce specific immunity more effectively than the plasmid expression individual antigen EBV-LMP2. In order to evaluate the anti-tumor effect of this DNA vaccine, we constructed a tumor bearing mouse model. After immunization, the tumor bearing mouse model, DNA vaccination with EBV-LMP2-CD40L plasmid significantly inhibited tumor growth in the tumor bearing mouse model and enhanced the tumor inhibition rate. This study demonstrated that encoding the EBV-LMP2 tumor antigen within an EBV-LMP2-CD40L DNA vaccine generates an effective antitumor response against EBV tumor, which may be a promising method to improve the antitumor immunity of DNA vaccine.