Study On Pharmacokinetics And Spatial And Temporal Expression In Mice Of DNA Vaccine Against Schistosoma Japonicum

Schistosomiasis, which was listed as one of the top ten fulminating infectious diseases, is a world-wide infectious disease and severely endangers the human and livestock health, thus becoming a public health problem of many countries. The conventional methods of prevention and treatment have many disadvantages in control of Schistosomiasis. Vaccine is one excellent measure of prevention and control Schistosomiasis. Therefore, the development of schistomiasis vaccine has a great economic and social value.DNA vaccine is a new concept which was first presented by wolff in 1990s and honoured as the 3rd generation vaccine and have many advantages to 1st, 2nd generation vaccines. In recent 20 years, more than 100 kinds of DNA vaccines have been developed and taken into clinical phase I or II trials, among which four kinds of DNA vaccines for livestock have been approved for marketing. However, so far, no DNA vaccine product for human was approved by FDA. The main reason is no universal rule to evaluate the safety of DNA vaccines. In this study, we focused on the distribution and metabolism rule of Schistosomiasis vaccine in BALB/c mouse. We constructed and prepared co-expressive and fusion expressive DNA vaccines containing Sj23 and EGFP genes. After immunization, we applied PCR, fluorescence microscope, and ELISA technologies to research the bio-distribution and persistence of DNA vaccine in BALB/c mice.The main results were as following:1. Two DNA vaccines of pVIVO2-Sj23/EGFP and pVIVO2-Sj23.EGFP which express antgen gene Sj23 and report gene EGFP were successfully constructed though recombinant PCR technology.2. Confirmation of antigen gene expression in vitro was performed by transfecting DNA vaccine into HEK-293 tumor cell line. 3. Fine purification and preparation of DNA vaccine was realized by high-salt induced protein degeneration and series of chromatographies.4. After DNA vaccine immunization by muscle injection, the bio-distribution and persistence of DNA vaccine in BALB/c mice were dectected by PCR, fluorescence microscope and ELISA methods. The results showed that DNA vaccine plasmid could quickly distribute in all tissues and organs of mice and persist in mice over 80 days; expressive antigen protein could persist over 7 days and antibody against Sj23 could persist over 70 days. All the results suggested that DNA vaccine could protect host against the challenge of Schistosoma japonicum.