Journal of Vaccines & Vaccination

Enhancement of immune response by Priming with DNA Vaccine

5^th Asia Pacific Global Summit and Expo on Vaccines & Vaccination

July 27-29, 2015 Brisbane, Australia

Kripa N. Nand1,3, Jagdish C. Gupta1, Amulya K. Panda2, S. K. Jain3 and G. P. Talwar1

Posters-Accepted Abstracts: J Vaccines Vaccin

Abstract:

Introduction: Immunization against human chorionic gonadotropin (hCG) prevents pregnancy in sexually active women of proven fertility, as shown by previous Phase II efficacy trials. In order to make the vaccine consistent in its linkage to the carrier, we developed a recombinant vaccine linking hCG? to LTB, B subunit of heat labile enterotoxin of E. coli which is a potent mucosal adjuvant. The hCG?-LTB vaccine was fairly immunogenic in mice of different genetic strains. Since a vaccine for control of fertility should ideally be effective in every recipient and be potent enough to generate above protective threshold antibody titres to prevent pregnancy, it was decided to investigate if prime-boost approach employing a combination of antihCG DNA and protein vaccines, can enhance the immune response. Methodology: hCG?-LTB protein vaccine was made and purified using yeast Pichia pastoris pPIC9k/GS115 host-vector system. DNA version of the vaccine was prepared by incorporating the gene encoding hCG?-LTB in eukaryotic plasmid VR1020 (DJ). Mycobacterium indicus pranii (MIP) was used as an immuno-modulator. Female inbred Balb C mice received 100 ?g of DNA vaccine in saline along with 5x106 cells of MIP/animal/dose route twice fortnightly followed by 2 ?g of alum adsorbed hCG?- LTB along with 5x106 cells of MIP by intramuscular route. Second group of mice was immunized by only protein version of the vaccine along with MIP. Results and Conclusions: Immunization with the DNA form of the recombinant hCG?-LTB vaccine twice at fortnightly interval followed by the proteinic form of the vaccine induced distinctly higher antibody response than the proteinic vaccine alone. DNA is not only cheaper to make, it is thermostable and does not require cold chain. Hence the employment of DNA for primary immunization is expected to reduce the cost besides the benefit of enhancing antibody response.