Advancing rapid point-of-care viral diagnostics to a clinical setting

Nanopore sensing of protein and peptide conformation for point-of-care applications

The global population's aging and growth will likely result in an increase in chronic aging-related diseases. Early diagnosis could improve the medical care and quality of life. Many diseases are linked to misfolding or conformational changes in biomarker peptides and proteins, which affect their function and binding properties. Current clinical methods struggle to detect and quantify these changes. Therefore, there is a need for sensitive conformational sensors that can detect low-concentration analytes in biofluids. Nanopore electrical detection has shown potential in sensing subtle protein and peptide conformation changes. This technique can detect single molecules label-free while distinguishing shape or physicochemical property changes. Its proven sensitivity makes nanopore sensing technology promising for ultra-sensitive, personalized point-of-care devices. We focus on the capability of nanopore sensing for detecting and quantifying conformational modifications and enantiomers in biomarker proteins and peptides and discuss this technology as a solution to future societal health challenges.

Disparities in cervical cancer screening programs in Cameroon: a scoping review of facilitators and barriers to implementation and uptake of screening

BACKGROUND

Cervical cancer is the fourth most common cancer worldwide. Organized screening has achieved significant reductions in cervical cancer incidence and mortality in many high-income countries (HICs). But the gap between HICs and low-and-middle-income countries (LMICs) is still substantial as the highest burden of the disease is in LMICs. Cameroon is a LMIC, where cervical cancer is the leading cause of cancer-related deaths among women, only 3-5% of eligible women have been screened and there is no effective national cervical cancer prevention program.

OBJECTIVE(S)

Identify facilitators and barriers to the implementation and uptake of existing cervical cancer screening programs in Cameroon to inform the implementation of a comprehensive national program.

METHODS

We conducted a scoping review using the Preferred Reporting Items for Systematic Reviews and Meta-analysis, extension for Scoping Reviews (PRISMA-ScR). Google Scholar and five electronic databases (PubMed, CINAHL, Embase, Cochrane library and Web of Science) were searched systematically from 2012 to 2022. Articles on cervical cancer screening programs in Cameroon were eligible for inclusion. Two reviewers independently screened search results and extracted relevant data.

RESULTS

A total of 182 articles were identified using our search strategy, and 20 were included. There was scarcity of publications from the North, Adamawa, East and South regions of Cameroon. Barriers and facilitators found were presented using the World Health Organisation framework for health systems. Cross-cutting barriers were: (1) the lack of a national training curriculum for screening providers with no elaborate, harmonized screening and treatment algorithm for cervical precancers; and (2) women's lack of information about cervical cancer screening activities. Conversely, provision of screening services at a low or no cost to women in some programs and the feasibility of using novel point of care screening methods like the Human Papillomavirus DNA test were identified as facilitators.

CONCLUSION

This scoping review indicates that there are knowledge and research gaps concerning the state of cervical cancer screening services in some regions of Cameroon. Moreover, it underlines the need for comprehensive cancer control policies and practices integrating all six-health system building blocks to reduce disparities between regions, and rural versus urban areas in Cameroon.

Sample-to-answer COVID-19 nucleic acid testing using a low-cost centrifugal microfluidic platform with bead-based signal enhancement and smartphone read-out

With its origin estimated around December 2019 in Wuhan, China, the ongoing SARS-CoV-2 pandemic is a major global health challenge. The demand for scalable, rapid and sensitive viral diagnostics is thus particularly pressing at present to help contain the rapid spread of infection and prevent overwhelming the capacity of health systems. While high-income countries have managed to rapidly expand diagnostic capacities, such is not the case in resource-limited settings of low- to medium-income countries. Aiming at developing cost-effective viral load detection systems for point-of-care COVID-19 diagnostics in resource-limited and resource-rich settings alike, we report the development of an integrated modular centrifugal microfluidic platform to perform loop-mediated isothermal amplification (LAMP) of viral RNA directly from heat-inactivated nasopharyngeal swab samples. The discs were pre-packed with dried n-benzyl-n-methylethanolamine modified agarose beads used to selectively remove primer dimers, inactivate the reaction post-amplification and allowing enhanced fluorescence detection via a smartphone camera. Sample-to-answer analysis within 1 hour from sample collection and a detection limit of approximately 100 RNA copies in 10 μL reaction volume were achieved. The platform was validated with a panel of 162 nasopharyngeal swab samples collected from patients with COVID-19 symptoms, providing a sensitivity of 96.6% (82.2-99.9%, 95% CI) for samples with Ct values below 26 and a specificity of 100% (90-100%, 95% CI), thus being fit-for-purpose to diagnose patients with a high risk of viral transmission. These results show significant promise towards bringing routine point-of-care COVID-19 diagnostics to resource-limited settings.

A novel RNA detection technique for point-of-care identification of pathogens

Despite significant progress in recent years to improve capabilities to diagnose infections at point-of-care (POC), there are still technical hurdles that need to be overcome to ensure proper medical interventions. Current microbial POC tests involve polymerase chain reaction (PCR) or sandwich immunoassay (IA) based detection formats. PCR is highly sensitive but requires complex instrumentation, whereas lateral flow (LF) based IA tests are handheld but lack sensitivity. We present here a portable and sensitive technique by integrating an isothermal RNA amplification approach with IA detection format. The technique comprises i) Nucleic Acid Sequence Based isothermal Amplification (NASBA), ii) amplicon tagging with hapten labeled probes, iii) capturing the amplicon and iv) formation of a sandwich complex with an antibody (Ab) that selectively recognizes the DNA-RNA duplex. The results can be extended to develop an automated, portable and highly sensitive diagnostic platform suitable for POC applications.

Automated optimization of double heater convective polymerase chain reaction devices based on CFD simulation database and artificial neural network model

This paper presents a framework for automated optimization of double-heater convective PCR (DH-cPCR) devices by developing a computational fluid dynamics (CFD) simulation database and artificial neural network (ANN) model. The optimization parameter space that includes the capillary tube geometries and the heater sizes of DH-cPCR is established, and a database consisting of nearly 10,000 CFD simulations is constructed. The database is then used to train a two-stage ANN models that select practically relevant data for modeling and predict PCR device performance. The trained ANN model is then combined with the gradient-based and the heuristics optimization approaches to search for optimal device configuration that possesses the shortest DNA doubling time. The entire design process including model meshing and configuration, parallel CFD computation, database organization, and ANN training and utilization is fully automated. Case studies confirm that the proposed framework can successfully find the optimal device configuration with an error of less than 0.3 s, and hence, representing a cost-effective and rapid solution of DH-cPCR device design.

Multiplexed Adaptive RT-PCR Based on L-DNA Hybridization Monitoring for the Detection of Zika, Dengue, and Chikungunya RNA

Reverse transcription polymerase chain reaction (RT-PCR) is the gold standard for the molecular diagnosis of many infectious diseases, including RNA viruses, but is generally limited to settings with access to trained personnel and laboratory resources. We have previously reported a fundamentally simpler thermal cycling platform called Adaptive PCR, which dynamically controls thermal cycling conditions during each cycle by optically monitoring the annealing and melting of mirror-image L-DNA surrogates of the PCR primers and targets. In this report, we integrate optically-controlled reverse transcription and single-channel monitoring of L-DNAs to develop a multiplexed Adaptive RT-PCR instrument and assay for the detection of Zika, dengue, and chikungunya virus RNA with high target specific and low limits of detection. The assay is demonstrated to detect as low as 5 copies/reaction of Zika or chikungunya RNA and 50 copies/reaction of dengue RNA. The multiplexed Adaptive RT-PCR instrument is robust and has many of the features required to implement diagnostic assays for RNA viruses in settings that lack traditional laboratory resources.

A fully-integrated and automated testing device for PCR-free viral nucleic acid detection in whole blood

Integrated devices for automated nucleic acid testing (NAT) are critical for infectious disease diagnosis to be performed outside of centralized laboratories. The gold standard methods for NAT are enzymatic amplification methods like the polymerase chain reaction that typically require expensive equipment and highly-trained personnel, limiting use in low-resource settings. A low-cost, integrated, rapid, portable and user-friendly point-of-care (POC) nucleic acid diagnostic device will improve the accessibility of NAT. Here, we present a fully integrated and simple-to-use POC device operated by a passive fluidic method that is able to perform a sequential multi-step assay to detect viral nucleic acids in blood. This simple device enabled the rapid detection of hepatitis C virus in blood in approximately 30 minutes with minimal sample handling by the user.

Estimating the value of point-of-care HPV testing in three low- and middle-income countries: a modeling study

Background

Where resources are available, the World Health Organization recommends cervical cancer screening with human papillomavirus (HPV) DNA testing and subsequent treatment of HPV-positive women with timely cryotherapy. Newer technologies may facilitate a same-day screen-and-treat approach, but these testing systems are generally too expensive for widespread use in low-resource settings.

Methods

To assess the value of a hypothetical point-of-care HPV test, we used a mathematical simulation model of the natural history of HPV and data from the START-UP multi-site demonstration project to estimate the health benefits and costs associated with a shift from a 2-visit approach (requiring a return visit for treatment) to 1-visit HPV testing (i.e., screen-and-treat). We estimated the incremental net monetary benefit (INMB), which represents the maximum additional lifetime cost per woman that could be incurred for a new point-of-care HPV test to be cost-effective, depending on expected loss to follow-up between visits (LTFU) in a given setting.

Results

For screening three times in a lifetime at 100% coverage of the target population, when LTFU was 10%, the INMB of the 1-visit relative to the 2-visit approach was I$13 in India, I$36 in Nicaragua, and I$17 in Uganda. If LTFU was 30% or greater, the INMB values for the 1-visit approach in all countries was equivalent to or exceeded total lifetime costs associated with screening three times in a lifetime. At a LTFU level of 70%, the INMB of the 1-visit approach was I$127 in India, I$399 in Nicaragua, and I$121 in Uganda.

Conclusions

These findings indicate that point-of-care technology for cervical cancer screening may be worthy of high investment if linkage to treatment can be assured, particularly in settings where LTFU is high.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3786-3) contains supplementary material, which is available to authorized users.

The Role of Affordable, Point-of-Care Technologies for Cancer Care in Low- and Middle-Income Countries: A Review and Commentary

As the burden of non-communicable diseases such as cancer continues to rise in low- and middle-income countries (LMICs), it is essential to identify and invest in promising solutions for cancer control and treatment. Point-of-care technologies (POCTs) have played critical roles in curbing infectious disease epidemics in both high- and low-income settings, and their successes can serve as a model for transforming cancer care in LMICs, where access to traditional clinical resources is often limited. The versatility, cost-effectiveness, and simplicity of POCTs warrant attention for their potential to revolutionize cancer detection, diagnosis, and treatment. This paper reviews the landscape of affordable POCTs for cancer care in LMICs with a focus on imaging tools, in vitro diagnostics, and treatment technologies and aspires to encourage innovation and further investment in this space.

Development of Multiplexed Infectious Disease Lateral Flow Assays: Challenges and Opportunities

Lateral flow assays (LFAs) are the mainstay of rapid point-of-care diagnostics, with the potential to enable early case management and transform the epidemiology of infectious disease. However, most LFAs only detect single biomarkers. Recognizing the complex nature of human disease, overlapping symptoms and states of co-infections, there is increasing demand for multiplexed systems that can detect multiple biomarkers simultaneously. Due to innate limitations in the design of traditional membrane-based LFAs, multiplexing is arguably limited to a small number of biomarkers. Here, we summarize the need for multiplexed LFA, key technical and operational challenges for multiplexing, inherent in the design and production of multiplexed LFAs, as well as emerging enabling technologies that may be able to address these challenges. We further identify important areas for research in efforts towards developing multiplexed LFAs for more impactful diagnosis of infectious diseases.

To expand coverage, or increase frequency: Quantifying the tradeoffs between equity and efficiency facing cervical cancer screening programs in low-resource settings

Cervical cancer is a leading cause of cancer death worldwide, with 85% of the disease burden residing in less developed regions. To inform evidence‐based decision‐making as cervical cancer screening programs are planned, implemented, and scaled in low‐ and middle‐income countries, we used cost and test performance data from the START‐UP demonstration project in Uganda and a microsimulation model of HPV infection and cervical carcinogenesis to quantify the health benefits, distributional equity, cost‐effectiveness, and financial impact of either (1) improving access to cervical cancer screening or (2) increasing the number of lifetime screening opportunities for women who already have access. We found that when baseline screening coverage was low (i.e., 30%), expanding coverage of screening once in a lifetime to 50% can yield comparable reductions in cancer risk to screening two or three times in a lifetime at 30% coverage, lead to greater reductions in health disparities, and cost 150 international dollars (I$) per year of life saved (YLS). At higher baseline screening coverage levels (i.e., 70%), screening three times in a lifetime yielded greater health benefits than expanding screening once in a lifetime to 90% coverage, and would have a cost‐effectiveness ratio (I$590 per YLS) below Uganda's per capita GDP. Given very low baseline coverage at present, we conclude that a policy focus on increasing access for previously unscreened women appears to be more compatible with improving both equity and efficiency than a focus on increasing frequency for a small subset of women.

What's new?

Most cervical cancer cases and deaths occur in less‐developed countries, where resource constraints challenge the planning and implementation of screening programs. The present report examines tradeoffs between equity and efficiency in cervical cancer screening approaches specifically in Uganda, where current baseline screening coverage is low. Analyses indicate that the expansion of access to once‐in‐a lifetime cervical cancer screening in areas with initially low baseline coverage is likely to yield greater benefits for health, distributional equity and cost‐effectiveness than increasing the number of screening opportunities per woman in low‐resource settings. Improving access for previously unscreened women should be a priority in such areas.

Consolidation of molecular testing in clinical virology

INTRODUCTION

The development of quantitative methods for the detection of viral nucleic acids have significantly improved our ability to manage disease progression and to assess the efficacy of antiviral treatment. Moreover, major advances in molecular technologies during the last decade have allowed the identification of new host genetic markers associated with antiviral drug response but have also strongly revolutionized the way we see and perform virus diagnostics in the coming years. Areas covered: In this review, we describe the history and development of virology diagnostic methods, dedicating particular emphasis on the gradual evolution and recent advances toward the introduction of multiparametric platforms for the syndromic diagnosis. In parallel, we outline the consolidation of viral genome quantification practice in different clinical settings. Expert commentary: More rapid, accurate and affordable molecular technology can be predictable with particular emphasis on emerging techniques (next generation sequencing, digital PCR, point of care testing and syndromic diagnosis) to simplify viral diagnosis in the next future.

Point-of-Care Viral Load Testing for Sub-Saharan Africa: Informing a Target Product Profile

Point-of-care viral load tests are being developed to monitor patients on antiretroviral therapy (ART) in sub-Saharan Africa. Test design involves trade-offs between test attributes, including accuracy, complexity, robustness, and cost. We used a model of the human immunodeficiency virus epidemic and ART program in Zimbabwe and found that the attributes of a viral load testing approach that are most influential for cost effectiveness are avoidance of a high proportion of failed tests or results not received, use of an approach that best facilitates retention on ART, and the ability to facilitate greater use of differentiated care, including through expanding coverage of testing availability.

New Approaches for Virus Detection through Multidisciplinary Partnerships

A critical requirement for controlling outbreaks of viral infection is sensitive and accurate diagnostics, which can be expensive and are frequently located in resource-intensive clinical laboratories. Outbreaks of many viral infections occur in countries where healthcare resources are limited and clinical laboratories scarce. This creates a fulfillment gap, one that could be filled through the development of inexpensive, sensitive, easy to use, and portable diagnostics. Here we describe our efforts to develop a diagnostic technology that detects viruses without needing to label the particle directly. Our approach has the advantage of speed and assay simplicity while maintaining high sensitivity. Essential in this approach has been the assembly of an integrated, diverse, and interdisciplinary team that worked together to evaluate technologies, spin-out a company, and produce a product for infectious disease diagnostics. The synergy of different individuals with complementary skills has been critical for the development of our transformative technology.

Adsorption and isolation of nucleic acids on cellulose magnetic beads using a three-dimensional printed microfluidic chip

While advances in genomics have enabled sensitive and highly parallel detection of nucleic acid targets, the isolation and extraction of the nucleic acids remain a critical bottleneck in the workflow. We present here a simple 3D printed microfluidic chip that allows for the vortex and centrifugation free extraction of nucleic acids. This novel microfluidic chip utilizes the presence of a water and oil interface to filter out the lysate contaminants. The pure nucleic acids, while bound on cellulose particles, are magnetically moved across the oil layer. We demonstrated efficient and rapid extraction of spiked Human Papillomavirus (HPV) 18 plasmids in specimen transport medium, in under 15 min. An overall extraction efficiency of 61% is observed across a range of HPV plasmid concentrations (5 × 10(1) to 5 × 10(6) copies/100 μl). The magnetic, interfacial, and viscous drag forces inside the microgeometries of the chip are modeled. We have also developed a kinetics model for the adsorption of nucleic acids on cellulose functionalized superparamagnetic beads. We also clarify here the role of carrier nucleic acids in the adsorption and isolation of nucleic acids. Based on the various mechanistic insights detailed here, customized microfluidic devices can be designed to meet the range of current and emerging point of care diagnostics needs.