Immunogenicity and efficacy of a DNA vaccine encoding a human anti-idiotype single chain antibody against nasopharyngeal carcinoma

G22, an anti-idiotype single chain antibody screened from human nasopharyngeal carcinoma phage anti-idiotype antibody library, has been already identified by He et al. G22 DNA vaccine was produced by cloning G22 gene and inserting the cloned gene into pcDNA3.1. To investigate the immunogenicity of pcDNA3.1-G22, C57BL/6 mice were immunized with the vaccine, pcDNA3.1 and PBS individually and the antibody response, T cell phenocyte at the 15th, 22th, 29th, 36th day after the last immunity were detected. In the tumor protection experiment, the immunized mice were then challenged with CMT-93-G22 cells or CMT-93-mock cells. The tumor size and the survival time of the animals were compared between these groups. The results showed that DNA vaccine pcDNA3.1-G22 could raise G22-specific humoral and cellular immune responses. Furthermore, pcDNA3.1-G22 could prolong the survival time and lessen the tumor size of the CMT-93-G22-bearing mice but had no protection effect on the mice attacked by CMT-93-mock cells. These results were expected to lay foundation for further studies on the clinical application of pcDNA3.1-G22 DNA vaccine.