Evaluation on the biosafety for the rabies virus glycoprotein/nucleoprotein DNA vaccine in dogs

Forty un-vaccinated dogs were immunized with rabies virus glycoprotein/nucleoprotein bivalent DNA vaccine pVGN for 3 times, and the biosafety was evaluated by means of the observation on the development of immune responses in the immunized dogs, monitoring the transference of the kanamycin-resistance gene, detection of the distributions of plasmid in the main organs and the injected tissues; observations of the pathological changes in the main organs as well as analysis of the influences of vaccine on the pregnant dogs and their puppies. The result showed that this DNA vaccine could induce excellent humoral immune responses in the immunized dogs without any abnormal clinical responses observed. Transference of the kanamycin-resistance gene in the DNA vaccine to the normal intestinal flora did not occur, and this gene was also not excreted into surroundings through intestinal flora, urine and saliva. The plasmid could be detected in heart, kidney and the injected tissues, and persisted in these area for 18, 14～18, 14 and 26 weeks respectively, while it could not be detected in liver. No integration of the plasmid DNA with the genomic DNA in the above-mentioned area was found. Also, there were no histopathological changes observed in the main organs. The vaccine had no influence on the pregnant dogs and their puppies. It indicates that this bivalent DNA vaccine not only possess the satisfied immunogenicity, but also has no problem on biosafety.