HPV-specific antibodies in female genital tract secretions captured via first-void urine retain their neutralizing capacity

ABSTRACT

Human papillomavirus (HPV) vaccines, primarily relying on neutralizing antibodies, have proven highly effective. Recently, HPV-specific antibodies have been detected in the female genital tract secretions captured by first-void urine (FVU), offering a minimally invasive diagnostic approach. In this study, we investigated whether HPV16-specific antibodies present in FVU samples retain their neutralizing capacity by using pseudovirion-based neutralization assays. Paired FVU and serum samples (vaccinated n = 25, unvaccinated n = 25, aged 18–25) were analyzed using two orthogonal pseudovirion-based neutralization assays, one using fluorescence microscopy and the other using luminescence-based spectrophotometry. Results were compared with HPV16-specific IgG concentrations and correlations between neutralizing antibodies in FVU and serum were explored. The study demonstrated the presence of neutralizing antibodies in FVU using both pseudovirion-based neutralization assays, with the luminescence-based assay showing higher sensitivity for FVU samples, while the fluorescence microscopy-based assay exhibited better specificity for serum and overall higher reproducibility. High Spearman correlation values were calculated between HPV16-IgG and HPV16-neutralizing antibodies for both protocols (r_s: 0.54–0.94, p < .001). Significant Spearman correlations between FVU and serum concentrations were also established for all assays (r_s: 0.44–0.91, p < .01). This study demonstrates the continued neutralizing ability of antibodies captured with FVU, supporting the hypothesis that HPV vaccination may reduce autoinoculation and transmission risk to the sexual partner. Although further protocol optimizations are warranted, these findings provide a foundation for future research and larger cohort studies that could have implications for the optimal design, evaluation, and implementation of HPV vaccination programs.

KEYWORDS:

• Neutralization
• HPV
• first-void urine
• vaccination
• human papillomavirus

Acknowledgments

We would like to express our gratitude to all women who volunteered to participate in this study and the clinical trial team nurses who helped with blood sample collection. We also would like to thank Dr. J. Schiller and Dr. C. Buck (National Cancer Institute, USA) for the plasmids required for PsV production and Dr. N. Christensen (Pennsylvania State University, USA) for the monoclonal antibodies.

Disclosure statement

Alex Vorsters is a cofounder and former board member of Novosanis (Subsidiary of OraSure Technologies Inc., Wijnegem, Belgium), a spin‐ off company of the University of Antwerp and was a minority shareholder until January 2019. The University of Antwerp received grants from Merck, GSK, Hologic, Abbott, Roche, and Cepheid to support the HPV Prevention and Control Board. The University of Antwerp received a project grant and honoraria fee for lectures, presentations, and speaker bureaus from Merck. Other authors declare that they have no conflict of interest.

Author contributions

Conceptualization, L.T., A.V.; methodology, L.T., M.L., F.M., W.H.D.V.; formal analysis, L.T.; resources, P.D., W.H.D.V., A.V.; data curation, L.T.; writing – original draft preparation, L.T.; writing – review and editing, L.T., M.L., F.M., P.D., W.H.D.V., A.V.; visualization, L.T.; supervision, W.H.D.V., A.V.; project administration, L.T., A.V.; funding acquisition, A.V. All authors read and approved the final manuscript.

Clinical trial registration

The study was registered on clinicaltrials.gov: NCT04391647.

Data availability statement

The data underlying this article will be shared on reasonable request to the corresponding author. Image analysis scripts are available on Github.

Ethics approval statement

The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board (or Ethics Committee) of UZA/University of Antwerp (B3002020000025, 30 April 2020).

Patient consent statement

All participants provided consent before participation.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2330168.

Additional information

Funding

This study was funded by the Industrial Research Fund of the University of Antwerp [IOF‐SBO, 44754], Merck Investigator Studies Program (MISP, 59401), and the European Union [ERC, URISAMP, 101040588]. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council Executive Agency. Neither the European Union nor the granting authority can be held responsible for them. W.H.D.V. is supported by the Research Foundation Flanders [FWO 1152918N, FWO G005819N, FWO I003420N and FWO IRI I000321N] and the University of Antwerp [BOF IMARK, mNEURO, IOF FFI210242].