FIG. 4.

HPV16-specific antitumor effect induced by vaginal immunization with Salmonella-expressing HPV16 L1 antigen in a prophylactic setting. Groups of C57BL/6 female mice (n = 10) were immunized twice at 2-week intervals with a PhoP^c kanL1S or a AroA kanL1S strain by either the vaginal or the nasal route and s.c. challenged with 5 × 10⁵ C3 tumor cells in the right flank 4 weeks after the last immunization. Tumor growth was monitored twice a week. (A) The tumor volumes of individual mice are shown at day 18 after the C3 challenge. The mean tumor volumes in each group are represented by horizontal bars. (B) The percent survival rates of PBS-treated control mice (thick solid line) and mice nasally immunized with PhoP^c kanL1S (punctate line) or vaginally immunized with PhoP^c kanL1S (dashed line) or AroA kanL1S (thin solid line) were monitored for 43 days. Mice sacrificed for ethical reasons when tumors reached 1.5 cm in diameter (3,400 mm³ in volume) were considered dead. Data are representative of two experiments. In panel A, statistical analyses were performed by using Student's t test.