DNA vaccines against the human papillomavirus type 16 E6 or E7 oncoproteins

DNA vaccines expressing the E6 or E7 oncoproteins of human papilloma virus type 16 (HPV-16) in either their wild-type form or fused to sequences that affect intracellular trafficking were tested for induction of protective immunity against tumor cell challenge in two models based on BALB/c and C57Bl/6 mice. The DNA vaccines to E7 gave uniformly disappointing results, while the DNA vaccine that expressed E6 linked to a viral leader sequence protected BALB/c mice against tumor cell challenge given before or after vaccination. The efficacy of this vaccine could be enhanced by a DNA vector prime/viral vector boost regimen. In contrast, priming of mice with the DNA vaccines to E7 reduced the efficacy of a viral vector expressing the same antigen.