Fig. 3.

Longevity of protection in mice immunized with lipopolysaccharide (LPS)-free MS2-16L2 VLPs. Lipopolysaccharide was removed from VLPs using 1X Triton X-114. 5 µg LPS-free VLPs without alum hydroxide were used to immunize mice once. The mice were then vaginally infected with HPV PsV16, 2 years after immunization. Luciferase activity and average radiance were determined as described in Fig. 1 legend.