A validated polyclonal antiserum-based immunoassay for assessment of HPV 16 L1 relative potency

Vaccine potency is typically evaluated using an assay that acts as a surrogate for biological activity. Although in vivo vaccines better represent human immunological responses, in vitro assays are preferred due to lower variability, higher throughput, easier validation and ethical considerations. In in vitro determination of Human Papillomavirus (HPV), Virus-like particle (VLP) vaccine potency currently depends on monoclonal antibody assays. However, these reagents are hard to obtain and currently are not available commercially. In this work, a polyclonal antiserum-based immunoassay was developed to evaluate the relative potency of Alhydrogel formulated HPV 16 VLPs. The repeatability and specificity were evaluated, and found that the assay was sensitive to small amounts of non-VLP HPV 16 L1 proteins. Finally, the assay was tested in comparison to the mouse effective dose 50 (ED50) assay on a limited number of batches. The agreement between these results suggests this test as a suitable surrogate for the in vivo test.