Studies On Pilot Production And Efficacy Of DNA Vaccine For Taenia Solium Cysticercosis

Taenia solium cysticercosis, a common zoonotic disease, is endemic in several countries of Latin America, Africa and Asia. The parasitic disease also causes enormous human suffering and great economic loss in endemic regions of Northwest China. Although incidence in China has markedly decreased with the improvements of socio-economic conditions, the disease is still far from being controlled. One of the approaches for the control of T. solium cystercosis is the use of vaccines in pigs. Effective and safe vaccines will not only improve animal health, meat yield and break the parasite life cycle, but also prevent taeniasis and consequently prevent human cysticercosis.Several studies including technology of pilot production, efficacy and safety about vaccine were performed on the basis of Taenia solium cysticercosis DNA vaccine, pcDNA3-cCl. i: To establish the preparation technology and quality criterion: Using fed-bath culture and tempture-changing technology to culture recombinant E.coli in high cell-density with high plasmid copy number in 50 L fermentor. On the basis of traditional alkaline-based plasmid prepararion method, we have also set up the method of pilot plasmid production. Relatively quality criterion were also established, ii: The efficacy of the DNA vaccine: Immunization of new-born pigs with DNA vaccine pcDNA3-cC1 induced protection against challenge with T. solium eggs by reduction of the metacestode number above 80%. The test on duration of protection showed that the pigs immunized with the DNA vaccine induced similar protection level after the challenge infection 3 weeks or 4 months later. We also investigated the duration of protection afforded to pigs immunized in two different prime-boost regimens: one is homologus prime and boost with a protein vaccine, and the other is prime with a DNA vaccine and boost with the protein vaccine. Groups of pigs that received the same vaccination regimen were then challenged with Taenia solium eggs at 6, 12 or 20 weeks post immunization (wpi), respectively. The results showed that all vaccinated pigs challenged at 6 or 12 wpi showed significant (P < 0.05) reduction in the development of cysts. When challenged at20 wpi, pigs primed with the DNA vaccine (pcDNA3-cCl) followed by two boosters of the protein vaccine (GST-cCl) showed significant (P < 0.05) protection against the challenge of T. solium eggs, whereas pigs receiving three injections of the protein vaccine showed no significant protection compared to non-vaccinated controls (P > 0.05). The use of a prime-boost strategy combining DNA and protein vaccines may be better than protein alone for the longevity of protection against the challenge of T. solium eggs. iii: Several concerns about the safety of the DNA vaccine were investigated: The tissue distribution of the intramuscular plasmid vaccine, immuny tolerability and possible adverse immunopathology following intramuscular injection. The results showed that the effects concerned were not detected in our experiments. On the other hand, the data of regular toxicity and tolerance experiments were also in normal region.