Anti-HPV activity testing for sanitary pads is a laboratory evaluation that quantifies how effectively a hygiene product inactivates human papillomavirus (HPV) under controlled contact conditions. Performed by accredited third-party laboratories using HPV pseudovirus-based infectivity assays, this testing provides manufacturers, brands, and regulators with objective data to substantiate antiviral performance claims. This article explains the technical principles, sample requirements, testing items, methodologies, acceptance criteria, and practical applications of anti-HPV activity testing for sanitary products.
Technical Overview
Human papillomavirus (HPV) is a small, non-enveloped, double-stranded DNA virus belonging to the Papillomaviridae family. More than 200 HPV genotypes have been identified, among which high-risk types such as HPV-16 and HPV-18 are associated with the majority of cervical cancer cases, while low-risk types such as HPV-6 and HPV-11 are linked to benign lesions. Because HPV is transmitted through direct contact with skin and mucosal surfaces, feminine hygiene products such as sanitary pads are increasingly marketed with functional claims of antiviral or anti-HPV activity, typically achieved through surface treatments with metal-ion agents, quaternary ammonium compounds, herbal extracts, or pH-modifying formulations.
Anti-HPV activity testing is designed to verify whether such functional materials can actually reduce the infectivity of HPV under standardized laboratory conditions. A key technical challenge is that authentic HPV cannot be efficiently propagated in conventional cell culture. Therefore, the internationally accepted approach is to use HPV pseudoviruses (PsV): single-round infectious particles assembled from recombinant L1 and L2 capsid proteins that package a reporter gene instead of the viral oncogene-containing genome. Pseudovirus systems are the same platform used worldwide in HPV vaccine neutralization assays and are recognized as a scientifically valid surrogate for infectivity measurement.
The core test principle is straightforward: a standardized pseudovirus inoculum is brought into contact with the test material for a defined period, the residual virus is recovered, and its remaining infectivity is quantified on susceptible reporter cells. The result is compared with an untreated control sample and expressed as an inactivation rate (percentage) and/or a log10 reduction value. The general methodological framework draws on ISO 18184:2019 (Textiles — Determination of antiviral activity of textile products) and ISO 21702:2019 (Measurement of antiviral activity on plastics and other non-porous surfaces), adapted for disposable hygiene products, with safety and hygiene compliance anchored in GB 15979 (Hygienic standard for disposable sanitary products) and biocompatibility principles from the ISO 10993 / GB/T 16886 series. Emerging industry group standards (designated with the "T/" prefix) have further specified pseudovirus-based anti-HPV performance requirements for disposable sanitary products.
Testing Samples
Finished Sanitary Pads and Panty Liners
Complete retail products, including day-use pads, night-use pads, and panty liners, can be tested as received. Testing the finished product evaluates the combined performance of all functional layers and is the most representative basis for a product-level anti-HPV claim.
Surface Nonwoven Fabrics (Top Sheets)
The top sheet is the layer in direct contact with skin and is frequently the carrier of the antiviral functional agent. Roll or cut samples of treated nonwoven fabric, with a matched untreated fabric serving as the negative control, are the most common test specimens for material-level verification.
Functional Chips, Coatings, and Additives
Many products incorporate discrete functional components, such as antiviral chips, negative-ion chips, plant-extract-infused strips, or antimicrobial coatings applied to a substrate. These components are tested individually to characterize the contribution of the active technology before integration into the finished product.
Absorbent Core and Supporting Components
Fluff pulp and superabsorbent polymer composites, transfer layers, and barrier materials may also be evaluated, particularly when the functional formulation is expected to migrate through the product structure during use.
General sample requirements include: sufficient quantity (typically 30–50 finished pieces or no less than 20 g of raw material per test condition), intact original packaging, documented batch and lot information, samples drawn from at least three production batches for consistency assessment, and confirmation that samples have been stored under the conditions specified by the manufacturer.
Testing Items
Typical test items for an anti-HPV evaluation program include:
- Anti-HPV inactivation rate against HPV-16 and HPV-18 pseudoviruses (the two principal high-risk types, optionally supplemented by HPV-6/HPV-11 low-risk types)
- Antiviral activity value expressed as log10 reduction of infectious titer
- Time-course inactivation profiles at multiple contact times (for example, 5 minutes, 30 minutes, 1 hour, and 2 hours)
- Antibacterial and antifungal activity against Staphylococcus aureus, Escherichia coli, and Candida albicans, determined per GB/T 20944 or equivalent plate and broth dilution methods
- pH and chemical safety screening of the product extract
- Supporting biocompatibility items such as cytotoxicity and skin irritation assessment per the ISO 10993 / GB/T 16886 series
- Claim durability verification after accelerated aging to support shelf-life statements
Testing Methods
Sample Preparation and Pretreatment
Specimens are cut to standardized dimensions or weighed to a defined mass, conditioned in a controlled environment, and, where necessary, surface-sterilized by an appropriate method that does not degrade the functional agent. Each test series includes an untreated control specimen, a virus-only control, and a cell viability control to ensure assay validity.
HPV Pseudovirus Preparation and Titration
Pseudoviruses are produced by transient transfection of HEK 293T/293FT cells with plasmids encoding codon-optimized L1 and L2 capsid proteins together with a reporter plasmid carrying firefly luciferase or green fluorescent protein. Following cell lysis, nuclease treatment, and density-gradient purification, the pseudovirus stock is titrated on reporter cells to establish the working infectivity. Because pseudoviruses are replication-defective and lack the HPV oncogene-containing genome, they can be handled under appropriate containment with a markedly reduced biosafety burden compared with authentic oncogenic HPV.
Contact, Incubation, and Virus Recovery
A defined volume of pseudovirus suspension is inoculated directly onto the test specimen and the untreated control, then incubated for the specified contact time at controlled temperature, commonly 25 °C ± 1 °C in line with ISO 18184 practice, or at a temperature justified by intended use. After the contact period, residual virus is eluted from each specimen using chilled culture medium. Parallel elutions at time zero establish the baseline recoverable titer.
Infectivity Determination and Molecular Quantification
Recovered virus is applied to susceptible reporter cells in microplate culture. After 48–72 hours of incubation, infectivity is quantified by luminescence (relative light units) or fluorescence signal, which correlates directly with the number of infectious particles. In parallel, quantitative real-time PCR (qPCR) can be performed on the eluates to measure residual reporter DNA copies, allowing laboratories to distinguish true loss of infectivity from mere physical retention of particles within the absorbent structure.
Calculation and Acceptance Criteria
The anti-HPV inactivation rate is calculated as (A − B) / A × 100%, where A is the infectivity recovered from the untreated control and B is the infectivity recovered from the treated specimen after the same contact time. The antiviral activity value is expressed as the log10 difference between control and treated titers, consistent with the calculation structure of ISO 18184. In common industry practice, an inactivation rate of at least 90% (a log10 reduction of at least 1.0) is regarded as the threshold for demonstrating anti-HPV activity, while a rate of 99.9% or higher (log10 reduction of at least 3.0) supports a strong virucidal performance claim. The test is considered valid only when virus recovery from the control meets the predefined minimum, control cell viability remains within acceptable limits, and replicate variability falls within specified tolerance.
Applications
Anti-HPV activity testing serves multiple purposes across the product life cycle:
- Claim substantiation and marketing compliance: objective laboratory evidence allows brands to make accurate, defensible antiviral claims and helps prevent the exaggerated or misleading advertising that regulatory authorities have increasingly scrutinized in the hygiene products sector.
- Research and development: comparative testing of formulations, dosages, and carrier materials guides the optimization of antiviral technologies before commercialization.
- Quality control and batch release: periodic verification of production batches ensures that the functional treatment remains consistent throughout manufacturing.
- E-commerce and retail platform requirements: major sales channels increasingly require third-party test reports as supporting documentation for functional product listings.
- Export support: test data aligned with ISO-based methodologies can be presented to international buyers and distributors as technical evidence of product performance.
- Regulatory communication: documented laboratory results support dialogue with market supervision authorities regarding product function statements.
FAQ
Why is a pseudovirus used instead of live HPV?
Authentic HPV cannot be reproducibly cultured in standard in vitro systems, and propagating oncogenic HPV would raise significant biosafety and ethical concerns. Pseudoviruses share the same capsid structure and cell-entry mechanism as native HPV but carry a harmless reporter genome and can complete only a single infection round. They are the globally accepted surrogate in HPV research, including vaccine neutralization testing coordinated under World Health Organization laboratory networks.
Which HPV types are typically tested?
HPV-16 and HPV-18 pseudoviruses are the standard test strains because these high-risk types account for the majority of HPV-associated severe disease. Testing against additional types such as HPV-6 and HPV-11 can be added to broaden the evidence base.
Does a positive test result mean the product prevents HPV infection or cervical cancer?
No. A positive result demonstrates that the material reduces HPV pseudovirus infectivity under controlled laboratory contact conditions. It does not constitute evidence of prevention of HPV transmission, protection against sexually transmitted infection, or prevention of any disease. Responsible claims must be limited to laboratory performance, and consumers should rely on vaccination, medical screening, and professional guidance for HPV-related health protection.
How long does the testing take?
A standard single-condition anti-HPV inactivation test, including pseudovirus preparation and cell-based readout, typically requires three to six weeks. Multi-time-point profiles, additional virus types, or combined antibacterial and biocompatibility programs may extend the timeline.
Is anti-HPV testing mandatory for sanitary pads?
Baseline compliance with GB 15979 and related hygiene standards is mandatory, but anti-HPV activity testing itself is not a compulsory national requirement. It becomes necessary in practice whenever a manufacturer wishes to make an antiviral or anti-HPV functional claim, as such claims must be supported by credible laboratory data.
What sample quantity should be submitted?
Laboratories generally request 30–50 finished products or a minimum of about 20 g of raw material per test condition, drawn from representative production batches with intact packaging and complete batch documentation. Exact requirements should be confirmed with the testing laboratory before submission.
How are results reported?
A typical report states the test virus type, contact time and temperature, recovered infectivity values for treated and control specimens, the calculated inactivation rate and log10 reduction, assay validity checks, and a conclusion referencing the applicable acceptance criteria. Reports from accredited third-party laboratories carrying recognized accreditation marks provide the strongest commercial and regulatory credibility.
