Each group of mice reproductive tracts (N=6) were challenged with different amount of PVs (HPV16:LucF) as indicated. An additional group of mice were challenged with 1E+07 PVs and 0.5% carrageenan. 48 hours after infection, mouse female reproductive tracts were harvested, protein lysates made, and luciferase assays were carried out to quantify the infectivity. Concentrations of total proteins were measure by Bradford protein assay. The infectivity level (relative luminescence units, RLU / µg) of mice treated with 1E+07 PVs was set as 100%. * P = 0.004 (Wilcoxon rank sum test, 2 sided).