Multiplex Solid-Phase Melt Curve Analysis for the Point-of-Care Detection of HIV-1 Drug Resistance

Semiautomated Electrochemical Melting Curve Analysis Device for the Detection of an Osteoporosis Associated Single Nucleotide Polymorphism in Blood

The detection of single nucleotide polymorphisms (SNPs) is of increasing importance in many areas including clinical diagnostics, patient stratification for pharmacogenomics, and advanced forensic analysis. In the work reported, we apply a semiautomated system for solid-phase electrochemical melting curve analysis (éMCA) for the identification of the allele present at a specific SNP site associated with an increased risk of bone fracture and predisposition to osteoporosis. Asymmetric isothermal recombinase polymerase amplification using ferrocene labeled forward primers was employed to generate single stranded redox labeled amplicons. In a first approach to demonstrate the proof of concept of combining asymmetric RPA with solid-phase éMCA, a simplified system housing a multielectrode array within a polymeric microsystem, sandwiched between two aluminum plates of a heater device, was used. Sample manipulation through the microfluidic channel was controlled by a syringe pump, and an external Ag/AgCl reference electrode was employed. Individual electrodes of the array were functionalized with four different oligonucleotide probes, each probe equivalent in design with the exception of the middle nucleotide. The isothermally generated amplicons were allowed to hybridize to the surface-tethered probes and subsequently subjected to a controlled temperature ramp, and the melting of the duplex was monitored electrochemically. A clear difference between the fully complementary and a single mismatch was observed. Having demonstrated the proof-of-concept, a device for automated éMCA with increased flexibility to house diverse electrode arrays with internal quasi-gold reference electrodes, higher resolution, and broader melting temperature range was developed and exploited for the detection of SNP hetero/homozygosity. Using the optimized conditions, the system was applied to the identification of the allele present at an osteoporosis associated SNP site, rs2741856, in 10 real fingerprick/venous blood samples, with results validated using Sanger sequencing.

Point-of-Care Tests for HIV Drug Resistance Monitoring: Advances and Potentials

HIV/AIDS is a global public health crisis that is yet to be contained. Effective management of HIV drug resistance (HIVDR) supported by close resistance monitoring is essential in achieving the WHO 95-95-95 targets, aiming to end the AIDS epidemic by 2030. Point-of-care tests (POCT) enable decentralized HIVDR testing with a short turnaround time and minimal instrumental requirement, allowing timely initiation of effective antiretroviral therapy (ART) and regimen adjustment as needed. HIVDR POCT is of particular significance in an era when ART access is scaling up at a global level and enhanced HIVDR monitoring is urgently needed, especially for low-to-middle-income countries. This article provides an overview of the currently available technologies that have been applied or potentially used in HIVDR POCT. It may also benefit the continued research and development efforts toward more innovative HIVDR diagnostics.

Low-Cost Platform for Multiplexed Electrochemical Melting Curve Analysis

Detection and identification of single nucleotide polymorphisms (SNPs) have garnered increasing interest in the past decade, finding potential application in detection of antibiotic resistance, advanced forensic science, as well as clinical diagnostics and prognostics, moving toward the realization of personalized medicine. Many different techniques have been developed for genotyping SNPs, and ideally these techniques should be rapid, easy-to-use, cost-effective, flexible, scalable, easily automated, and requiring minimal end-user intervention. While high-resolution melting curve analysis has been widely used for the detection of SNPs, fluorescence detection does not meet many of the desired requirements, and electrochemical detection is an attractive alternative due to its high sensitivity, simplicity, cost-effectiveness, and compatibility with microfabrication. Herein, we describe the multiplexed electrochemical melting curve analysis of duplex surfaces tethered to electrodes of an array. In this approach, thiolated probes designed to hybridize to a DNA sequence containing the SNP to be interrogated are immobilized on gold electrodes. Asymmetric PCR using a ferrocene-labeled forward primer is used to generate this single-stranded redox-labeled PCR amplicon. Following hybridization with the probe immobilized on the electrode surface, the electrode array is exposed to a controlled ramping of temperature, with concomitant constant washing of the electrode array surface while simultaneously carrying out voltammetric measurements. The optimum position of the site complementary to the SNP site in the immobilized probe to achieve maximum differentiation in melting temperature between wild-type and single base mismatch, thus facilitating allelic discrimination, was determined and applied to the detection of a cardiomyopathy associated SNP.

Biophysical Characterization of Novel DNA Aptamers against K103N/Y181C Double Mutant HIV-1 Reverse Transcriptase

The human immunodeficiency virus type-1 Reverse Transcriptase (HIV-1 RT) plays a pivotal role in essential viral replication and is the main target for antiviral therapy. The anti-HIV-1 RT drugs address resistance-associated mutations. This research focused on isolating the potential specific DNA aptamers against K103N/Y181C double mutant HIV-1 RT. Five DNA aptamers showed low IC50 values against both the KY-mutant HIV-1 RT and wildtype (WT) HIV-1 RT. The kinetic binding affinity forms surface plasmon resonance of both KY-mutant and WT HIV-1 RTs in the range of 0.06–2 μM and 0.15–2 μM, respectively. Among these aptamers, the KY44 aptamer was chosen to study the interaction of HIV-1 RTs-DNA aptamer complex by NMR experiments. The NMR results indicate that the aptamer could interact with both WT and KY-mutant HIV-1 RT at the NNRTI drug binding pocket by inducing a chemical shift at methionine residues. Furthermore, KY44 could inhibit pseudo-HIV particle infection in HEK293 cells with nearly 80% inhibition and showed low cytotoxicity on HEK293 cells. These together indicated that the KY44 aptamer could be a potential inhibitor of both WT and KY-mutant HIV-RT.

Rapid HIV-1 drug resistance testing in a resource limited setting: the Pan Degenerate Amplification and Adaptation assay (PANDAA)

Introduction

pre-treatment drug resistance (PDR) can compromise the 3^rd 95-95-95 global target for viral load suppression. The high complexity and cost of genotyping assays limits routine testing in many resource limited settings (RLS). We assessed the performance of a rapid HIV-1 drug resistance assay, the Pan Degenerate Amplification and Adaptation (PANDAA) assay when screening for significant HIV-1 drug resistance mutations (DRMs) such as K65R, K103NS, M184VI, Y181C and G190A. Methods: we used previously generated amplicons from a cross-sectional study conducted between October 2018 and February 2020 of HIV-1 infected antiretroviral therapy (ART)-naïve or those reinitiating 1^st line ART (18 years or older). The performance of the PANDAA assay in screening K65R, K103NS, M184VI, Y181C, and G190A mutations compared to the reference assay, Sanger sequencing was evaluated by Cohen´s kappa coefficient on Stata version 14 (StataCorp LP, College Station, TX, USA).

Results

one hundred and twenty samples previously characterized by Sanger sequencing were assessed using PANDAA. PDR was found in 14% (17/120). PDR to non-nucleoside reverse transcriptase inhibitors (NNRTIs) was higher at 13% (16/120) than PDR to nucleotide reverse transcriptase inhibitors (NRTIs), 3% (3/120). The PANDAA assay showed a strong agreement with the reference assay, i.e. Sanger sequencing for all five target DRMs (kappa (95%CI); 0.93 (0.78-0.98)) and NNRTI DRMs (kappa (95%CI); 0.93 (0.77-0.980), and a perfect agreement for NRTI DRMs (kappa (95%CI); 1.00 (0.54-1.00)).

Conclusion

the PANDAA assay is a simple and rapid method to identify significant HIV DRMs in plasma samples as an alternative to Sanger sequencing in many RLS.

Near-point-of-care assay with a visual readout for detection of HIV-1 drug resistance mutations: A proof-of-concept study

Human immunodeficiency virus (HIV) infection is a chronic disease that can be treated with antiretroviral (ARV) therapy. However, the success of this treatment has been jeopardized by the emergence of HIV infections resistant to ARV drugs. In low-to middle-income countries (LMICs), where transmission of resistant viruses has increased over the past decade, there is an urgent need to improve access to HIV drug resistance testing. Here, we present a proof-of-concept study of a rapid and simple molecular method to detect two major mutations (K103 N, Y181C) conferring resistance to first-line nonnucleoside reverse transcriptase inhibitor regimens. Our near-point-of-care (near-POC) diagnostic test, combining a sequence-specific primer extension and a lateral flow DNA microarray strip, allows visual detection of HIV drug resistance mutations (DRM) in a short turnaround time (4 h 30). The assay has a limit of detection of 100 copies of plasmid DNA and has a higher sensitivity than standard Sanger sequencing. The analytical performance was assessed by use of 16 plasma samples from individuals living with HIV-1 and results demonstrated the specificity and the sensitivity of this approach for multiplex detection of the two DRMs in a single test. Furthermore, this near-POC assay could be easily taylored to detect either new DRMs or DRM of from various HIV clades and might be useful for pre-therapy screening in LMICs with high levels of transmitted drug resistance.

Geospatial Spread of Antimicrobial Resistance, Bacterial and Fungal Threats to Coronavirus Infectious Disease 2019 (COVID-19) Survival, and Point-of-Care Solutions

CONTEXT.—

Point-of-care testing (POCT) is inherently spatial, that is, performed where needed, and intrinsically temporal, because it accelerates decision-making. POCT efficiency and effectiveness have the potential to facilitate antimicrobial resistance (AMR) detection, decrease risks of coinfections for critically ill patients with coronavirus infectious disease 2019 (COVID-19), and improve the cost-effectiveness of health care.

OBJECTIVES.—

To assess AMR identification by using POCT, describe the United States AMR Diagnostic Challenge, and improve global standards of care for infectious diseases.

DATA SOURCES.—

PubMed, World Wide Web, and other sources were searched for papers focusing on AMR and POCT. EndNote X9.1 (Clarivate Analytics) consolidated abstracts, URLs, and PDFs representing approximately 500 articles were assessed for relevance. Panelist insights at Tri•Con 2020 in San Francisco and finalist POC technologies competing for a US $20,000,000 AMR prize are summarized.

CONCLUSIONS.—

Coinfections represent high risks for COVID-19 patients. POCT potentially will help target specific pathogens, refine choices for antimicrobial drugs, and prevent excess morbidity and mortality. POC assays that identify patterns of pathogen resistance can help tell us how infected individuals spread AMR, where geospatial hotspots are located, when delays cause death, and how to deploy preventative resources. Shared AMR data "clouds" could help reduce critical care burden during pandemics and optimize therapeutic options, similar to use of antibiograms in individual hospitals. Multidisciplinary health care personnel should learn the principles and practice of POCT, so they can meet needs with rapid diagnostic testing. The stakes are high. Antimicrobial resistance is projected to cause millions of deaths annually and cumulative financial loses in the trillions by 2050.

Genotypic Methods for HIV Drug Resistance Monitoring: The Opportunities and Challenges Faced by China

AIDS is a globalized infectious disease. In 2014, UNAIDS launched a global project of "90-90-90" to end the HIV epidemic by 2030. The second and third 90 require 90% of HIV-1 infected individuals receiving antiretroviral therapy (ART) and durable virological suppression. However, wide use of ART will greatly increase the emergence and spreading of HIV drug resistance and current HIV drug resistance test (DRT) assays in China are seriously lagging behind, hindering to achieve virological suppression. Therefore, recommending an appropriate HIV DRT method is critical for HIV routine surveillance and prevention in China. In this review, we summarized the current existing HIV drug resistance genotypic testing methods around the world and discussed the advantages and disadvantages of these methods.