Viral DNA Vaccines
Guest Editor: Karin Mölling, Zurich

Paper

Plasmid DNA Vaccines: Tissue Distribution and Effects of DNA Sequence, Adjuvants and Delivery Method on Integration into Host DNA
Sujata Manam, Brian J. Ledwith, Amy B. Barnum, Philip J. Troilo, Cindy J. Pauley, Laural B. Harper, Thomas G. Griffiths II, Zhutian Niu, Lyudmila Denisova, Thy T. Follmer, Stephen J. Pacchione, Zhibin Wang, Carolann M. Beare, Walter J. Bagdon, Warren W. Nichols

Department of Safety Assessment, Merck Research Laboratories, West Point, Pa., USA

Address of Corresponding Author

Intervirology 2000;43:273-281 (DOI: 10.1159/000053994)

  Key Words

• DNA vaccine
• Plasmid
• Recombination
• HIV
• Human papilloma virus
• Influenza

  Abstract

A variety of factors could affect the frequency of integration of plasmid DNA vaccines into host cellular DNA, including DNA sequences within the plasmid, the expressed gene product (antigen), the formulation, delivery method, route of administration, and the type of cells exposed to the plasmid. In this report, we examined the tissue distribution and potential integration of plasmid DNA vaccines following intramuscular administration in mice and guinea pigs. We compared needle versus Biojector (needleless jet) delivery, examined the effect of aluminum phosphate adjuvants, compared the results of different plasmid DNA vaccines, and tested a gene (the human papilloma virus E7 gene) whose protein product is known to increase integration frequency in vitro. Six weeks following intramuscular injection, the vast majority of the plasmid was detected in the muscle and skin near the injection site; lower levels of plasmid were also detected in the draining lymph nodes. At early time points (1-7 days) after injection, a low level of systemic exposure could be detected. Occasionally, plasmid was detected in gonads, but it dissipated rapidly and was extrachromosomal - indicating a low risk of germline transmission. Aluminum phosphate adjuvant had no effect on the tissue distribution and did not result in a detectable increase in integration frequency. Biojector delivery, compared with needle injection, greatly increased the uptake of plasmid (particularly in skin at the injection site), but did not result in a detectable increase in integration frequency. Finally, injection of a plasmid DNA vaccine containing the human papilloma virus type 16 E7 gene, known to increase integration in vitro, did not result in detectable integration in mice. These results suggest that the risk of integration following intramuscular injection of plasmid DNA is low under a variety of experimental conditions.

Copyright © 2001 S. Karger AG, Basel

  Author Contacts

Sujata Manam, PhD
Merck Research Laboratories
West Point, PA 19486 (USA)
Tel. +1 215 652 7494, Fax +1 215 652 7758
E-Mail sujata_manam@merck.com

  Article Information

Number of Print Pages : 9
Number of Figures : 0, Number of Tables : 8, Number of References : 21