Anti-viral protection in mice treated with anti-CD25 mAbs and B16F10 cells. Groups of 3-6 naive mice (A), anti-beta-gal mAb-treated (B) or anti-CD25 mAb-treated (C), B16F10-inoculated mice were challenged with rVVtyr. Naive (D) and anti-CD25 mAb-treated B16F10-inoculated (E) mice were also infected with rVVUb-R-NP. Tumour immune mice exhibiting signs of depigmentation were infected with rVVTyr (F). Virus titres were measured in ovaries 5 days later. In cases where equivalent titres were obtained in different mice the number of mice used are shown in parenthesis next to the corresponding symbol. The dashed line represents the limit of sensitivity of the assay. Using Fisher's exact test we found that the increased ability of anti-CD25 mAb-treated, B16F10-inoculated mice to clear rVVTyr compared to those receiving isotype control mAbs was significant (P=0.047).