DNA vaccination prevents and/or delays carcinoma development of papillomavirus-induced skin papillomas on rabbits

Malignant progression is a life-threatening consequence of human papillomav irus-associated lesions. In this study, we tested the efficacy of papilloma virus early-gene-based vaccines for prevention of carcinoma development of papillomavirus-induced skin papillomas on rabbits. Rabbit skin papillomas w ere initiated by infection with cottontail rabbit papillomavirus (CRPV), Th e papillomas were allowed to grow for 3 months without any treatment interv ention. Rabbits were then immunized by gene gun-mediated intracutaneous adm inistration of four DNA plasmids encoding CRPV E1, E2, E6, and E7 genes, re spectively. All eight control rabbits receiving vector alone developed inva sive carcinoma within 8 to 13 months. In contrast, only two of eight vaccin ated rabbits developed carcinoma at 12 and 15 months, respectively. Papillo ma growth was suppressed in the majority of vaccinated rabbits but not comp letely eradicated. These results indicate that gene gun-mediated immunizati on with papillomavirus early genes may be a promising strategy for preventi on of malignant progression of human papillomavirus-associated lesions in h umans.