1. ¹Department of Obstetrics and Gynecology, College of Medicine, National Taiwan University, Taipei, Taiwan
2. ²Department of Anesthesiology, College of Medicine, National Taiwan University, Taipei, Taiwan
3. ³Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan

Correspondence: Dr W-F Cheng, Department of Obstetrics and Gynecology, National Taiwan University Hospital, Taipei, Taiwan. E-mail: wenfangcheng@yahoo.com

Received 4 September 2008; Revised 24 February 2009; Accepted 24 February 2009; Published online 9 April 2009.

Abstract

Genetic immunization strategies have largely focused on the use of plasmid DNA with a gene gun. However, there remains a clear need to further improve the efficiency, safety, and cost of potential DNA vaccines. The gold particle-coated DNA format delivered through a gene gun is expensive, time and process consuming, and raises aseptic safety concerns. This study aims to determine whether a low-pressured gene gun can deliver noncarrier naked DNA vaccine without any particle coating, and generate similarly strong antigen-specific immunologic responses and potent antitumor effects compared with gold particle-coated DNA vaccine. Our results show that mice vaccinated with noncarrier naked chimeric CRT/E7 DNA lead to dramatic increases in the numbers of E7-specific CD8⁺ T-cell precursors and markedly raised titers of E7-specific antibodies. Furthermore, noncarrier naked CRT/E7 DNA vaccine generated potent antitumor effects against subcutaneous E7-expressing tumors and pre-established E7-expressing metastatic pulmonary tumors. In addition, mice immunized with noncarrier naked CRT/E7 DNA vaccine had significantly less burning effects on the skin compared with those vaccinated with gold particle-coated CRT/E7 DNA vaccine. We conclude that noncarrier naked CRT/E7 DNA vaccine delivered with a low-pressured gene gun can generate similarly potent immunologic responses and effective antitumor effects has fewer side effects, and is more convenient than conventional gold particle-coated DNA vaccine.