Infectious Titres of Human Papillomaviruses (HPVs) in Patient Lesions, Methodological Considerations in Evaluating HPV Infectivity and Implications for the Efficacy of High-Level Disinfectants

Abstract

Background: Recent publications from a single research group have suggested that aldehyde-based high-level disinfectants (HLDs), such as ortho-phthalaldehyde (OPA), are not effective at inactivating HPVs and that therefore, patients may be at risk of HPV infection from medical devices. These results could have significant public health consequences and therefore necessitated evaluation of their reproducibility and clinical relevance. Methods: We developed methods and used standardised controls to: (1) quantify the infectious levels of clinically-sourced HPVs from patient lesions and compare them to laboratory-derived HPVs, (2) evaluate experimental factors that should be controlled to ensure consistent and reproducible infectivity measurements of different HPV genotypes, and (3) determine the efficacy of select HLDs. Findings: A novel focus forming unit (FFU) infectivity assay demonstrated that exfoliates from patient anogenital lesions and respiratory papillomas yielded infectious HPV burdens up to 2·7x103 FFU; therefore, using 2·2x102 to 1·0x104 FFU of laboratory-derived HPVs in disinfection assays provides a relevant range for clinical exposures. RNase and neutralising antibody sensitivities were used to ensure valid infectivity measures of tissue-derived and recombinant HPV preparations. HPV infectivity was demonstrated over a dynamic range of 4 to 5 log10; and disinfection with OPA and hypochlorite was achieved over 3 to >4 log10 with multiple genotypes of tissue-derived and recombinant HPV isolates. Interpretation: This work, along with a companion publication from an independent lab in this issue, address a major public health question by showing that HPVs are susceptible to HLDs. Funding: Advanced Sterilization Products; US NIH (R01CA207368, U19AI084081, P30CA118100). Declaration of Interests: M.A.O. reports grants, personal fees and non-financial support from Advanced Sterilization Products, grants from U.S. National Institutes of Health, during the conduct of the study; In addition, Dr. Ozbun has a patent “Quantitative Methods for Assessing Papillomavirus Infections” pending. A.G.W. reports personal fees and non-financial support from ASCCP, non-financial support from ACOG, non-financial support from Loktal Medical Electronics, personal fees and non-financial support from CSCCP (Chinese Society for colposcopy and cervical pathology, personal fees and non- financial support from Henan People's Regional Hospital, personal fees from SouthCentral Foundation (Alaska Native Corp), non-financial support from FECOLSOG (Colombian colposcopy society), non- financial support from COMEGIC (Mexican colposcopy society), non-financial support from Doctors Hospital at Renaissance, non-financial support from MD Anderson, non-financial support from Univ Texas Rio Grande Valley, non-financial support from Global Coalition against Cervical Cancer, non-financial support from AIDS Malignancy Consortium, personal fees and non-financial support from Deaconess Beth Israel Hospital, personal fees and non-financial support from Texas Tech University, personal fees and non-financial support from ABPTGIC (Brazilian colposcopy society), outside the submitted work. V.B., N.A.P, R.T.S., E.C.B. and R.M. have nothing to disclose. A.S., J.Y. and M.R. are employees of Advanced Sterilization Products. G.E. is an employee and shareholder of Johnson & Johnson, which was the parent company for Advanced Sterilization Products and Janssen Pharmaceutica NV at the time the research was conducted. Ethics Approval Statement: The collection of clinical material used in this study complied with the Helsinki Declaration of 1975, as revised in 1983 and described previously and was approved by the University of New Mexico Health Sciences Center’s Human Research Protections Office (UNM HRPO #17-202 IRB Approved Protocol).