Fig. 2. Twice immunization of VP1/CRA induced strong but not durable antitumor effect.

a Schematic represents the treatment schedule. Naive BALB/c mice were subcutaneously inoculated with 1 × 10⁶ of CMS5-VP1 tumor cells in the left flank back on day 0. When tumors were palpable, the tumor-bearing mice were divided randomly and followed by twice intramuscular administration of VP1/CRA, VP1/CA, VP1/RA, VP1/A or PBS in the left hind limp on days 5 and 12. b Tumor volume was measured with digital calipers every 3 days. Mice were euthanized when tumor volumes reached 2000 mm³ or when tumors began to impair mobility or ulcerate. c After tumor completely regressed in group of VP1/CRA, tumor-free mice were rechallenged with 1 × 10⁶ of CMS5-VP1 on day 42. Tumor growth of rechallenged CMS5-VP1 were measured with digital calipers every 3 days and tumor volumes were calculated. Statistics by ordinary two-way ANOVA, p:0.1234(NS), 0.0332(*), 0.0021(**), 0.0002(***), <0.0001(****).