Point of Care Technologies for HIV

Recent advances in nanobiosensors for sustainable healthcare applications: A systematic literature review

The need for novel healthcare treatments and drugs has increased due to the expanding human population, detection of newer diseases, and looming pandemics. The development of nanotechnology offers a platform for cutting-edge in vivo non-invasive monitoring and point-of-care-testing (POCT) for rehabilitative disease detection and management. The advancement and uses of nanobiosensors are currently becoming more common in a variety of scientific fields, such as environmental monitoring, food safety, biomedical, clinical, and sustainable healthcare sciences, since the advent of nanotechnology. The identification and detection of biological patterns connected to any type of disease (communicable or not) have been made possible in recent years by several sensing techniques utilizing nanotechnology concerning biosensors and nanobiosensors. In this work, 2218 articles are drawn and screened from six digital databases out of which 17 were shortlisted for this review by using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) technique. As a result, this study uses a systematic methodology to review some recently developed extremely sensitive nanobiosensors, along with their biomedical, point-of-care diagnostics (POCD), or healthcare applications and their capabilities, particularly for the prediction of some fatal diseases based on a few of the most recent publications. The potential of nanobiosensors for medicinal, therapeutic, or other sustainable healthcare applications, notably for ailments diagnostics, is also recognized as a way forward in the manifestation of future trends.

Contribution des diagnostics au points de service dans l’identification de la maladie à VIH avancée

BACKGROUND

Médecins Sans Frontières Belgium installed point-of-care (POC) diagnostics for the early detection of advanced HIV disease (AHD), and in its presence, TB and cryptococcosis, in six health centres (Kasai, St Ambroise, St Joseph, Libondi, Lisanga and Kimia) in Kinshasa, Democratic Republic of the Congo (DRC).

OBJECTIVE

To document their contribution to the diagnosis of these conditions.

METHOD

This is a retrospective cross-sectional study of HIV-positive adolescents and adults admitted with suspected AHD. A comparison 2 years before and 2 years after installation of POC was performed.

RESULTS

A total of 745 and 887 patients were included before and after POC, respectively. The mean age was 39.7 years (standard deviation [SD] 12.04); 66% (n = 1,077) were women. Patients with CD4 counts increased from 40.3% (n = 300) to 64.4% (n = 573) (P < 0.001). After the installation of POC, they ranged from 47.8% (Lisanga) to 97.1% (Kasai). The proportion of AHD was comparable (n = 158, 52.7% vs. n = 288, 50.3%; P = 0.779). Among patients with AHD, TB was detected in 28.5% (n = 82), of which 41.5% (n = 34) were confirmed; cryptococcosis was detected in 24.7% (n = 71), of which 9.9% (n = 7) were confirmed. Disparities between centres were observed.

CONCLUSION

The POCs have increased patient access to CD4 testing and diagnosis of AHD in the six centres in DRC. However, actions are required to improve this performance, including screening for TB and cryptococcosis.

Point-of-care viral load tests to detect high HIV viral load in people living with HIV/AIDS attending health facilities

BACKGROUND

Viral load (VL) testing in people living with HIV (PLHIV) helps to monitor antiretroviral therapy (ART). VL is still largely tested using central laboratory-based platforms, which have long test turnaround times and involve sophisticated equipment. VL tests with point-of-care (POC) platforms capable of being used near the patient are potentially easy to use, give quick results, are cost-effective, and could replace central or reference VL testing platforms.

OBJECTIVES

To estimate the diagnostic accuracy of POC tests to detect high viral load levels in PLHIV attending healthcare facilities.

SEARCH METHODS

We searched eight electronic databases using standard, extensive Cochrane search methods, and did not use any language, document type, or publication status limitations. We also searched the reference lists of included studies and relevant systematic reviews, and consulted an expert in the field from the World Health Organization (WHO) HIV Department for potentially relevant studies. The latest search was 23 November 2020.

SELECTION CRITERIA

We included any primary study that compared the results of a VL test with a POC platform to that of a central laboratory-based reference test to detect high viral load in PLHIV on HIV/AIDS care or follow-up. We included all forms of POC tests for VL as defined by study authors, regardless of the healthcare facility in which the test was conducted. We excluded diagnostic case-control studies with healthy controls and studies that did not provide sufficient data to create the 2 × 2 tables to calculate sensitivity and specificity. We did not limit our study inclusion to age, gender, or geographical setting.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles, abstracts, and full texts of the search results to identify eligible articles. They also independently extracted data using a standardized data extraction form and conducted risk of bias assessment using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Using participants as the unit of analysis, we fitted simplified univariable models for sensitivity and specificity separately, employing a random-effects model to estimate the summary sensitivity and specificity at the current and commonly reported World Health Organization (WHO) threshold (≥ 1000 copies/mL). The bivariate models did not converge to give a model estimate.

MAIN RESULTS

We identified 18 studies (24 evaluations, 10,034 participants) defining high viral loads at main thresholds ≥ 1000 copies/mL (n = 20), ≥ 5000 copies/mL (n = 1), and ≥ 40 copies/mL (n = 3). All evaluations were done on samples from PLHIV retrieved from routine HIV/AIDS care centres or health facilities. For clinical applicability, we included 14 studies (20 evaluations, 8659 participants) assessing high viral load at the clinical threshold of ≥ 1000 copies/mL in the meta-analyses. Of these, sub-Saharan Africa, Europe, and Asia contributed 16, three, and one evaluation respectively. All included participants were on ART in only nine evaluations; in the other 11 evaluations the proportion of participants on ART was either partial or not clearly stated. Thirteen evaluations included adults only (n = 13), five mixed populations of adults and children, whilst in the remaining two the age of included populations was not clearly stated. The majority of evaluations included commercially available tests (n = 18). Ten evaluations were POC VL tests conducted near the patient in a peripheral or onsite laboratory, whilst the other 10 were evaluations of POC VL tests in a central or reference laboratory setting. The test types evaluated as POC VL tests included Xpert HIV-1 Viral Load test (n = 8), SAMBA HIV-1 Semi-Q Test (n = 9), Alere Q NAT prototype assay for HIV-1 (n = 2) and m-PIMA HIV-1/2 Viral Load test (n = 1). The majority of evaluations (n = 17) used plasma samples, whilst the rest (n = 3) utilized whole blood samples. Pooled sensitivity (95% confidence interval (CI)) of POC VL at a threshold of ≥ 1000 copies/mL was 96.6% (94.8 to 97.8) (20 evaluations, 2522 participants), and pooled specificity (95% CI) was 95.7% (90.8 to 98.0) (20 evaluations, 6137 participants). Median prevalence for high viral load (≥ 1000 copies/mL) (n = 20) was 33.4% (range 6.9% to 88.5%). Limitations The risk of bias was mostly assessed as unclear across the four domains due to incomplete reporting.

AUTHORS' CONCLUSIONS

We found POC VL to have high sensitivity and high specificity for the diagnosis of high HIV viral load in PLHIV attending healthcare facilities at a clinical threshold of ≥ 1000 copies/mL.

Development of Loop-Mediated Isothermal Amplification Assay for Detection of Clinically Significant Members of Acinetobacter calcoaceticus-baumannii Complex and Associated Carbapenem Resistance

Background:Acinetobacter calcoaceticus–baumannii (ACB) complex has emerged as an important nosocomial pathogen and is associated with life-threatening infections, especially among ICU patients, including neonates. Carbapenem resistance in Acinetobacter baumannii has emerged globally and is commonly mediated by bla_OXA-23. Clinically significant infections with carbapenem-resistant Acinetobacter baumannii (CRAB) are a major concern since therapeutic options are limited and associated mortality is high. Early diagnosis of both the pathogen and resistance is important to initiate the optimal therapy and prevent selection of resistance. In the current study, a loop-mediated isothermal amplification (LAMP) assay was developed for rapid detection of the ACB complex and carbapenem resistance mediated by bla_OXA-23.

Methodology: Universal LAMP primers were designed for the detection of significant members of the ACB complex and carbapenem resistance targeting the ITS 16S–23S rRNA and bla_OXA-23 gene respectively. The optimal conditions for the LAMP assay were standardized for each primer set using standard ATCC strains. The sensitivity of the LAMP assay was assessed based on the limit of detection (LOD) using different DNA concentrations and colony counts. The specificity of LAMP was determined using the non-ACB complex and non-Acinetobacter species. The results of the LAMP assay were compared with those of polymerase chain reaction (PCR).

Results: The optimal temperature for the LAMP assay was 65°C, and the detection time varied with various primers designed. Using the ITS Ab1 primer, LODs of LAMP and PCR assays were 100 pg/μl and 1 ng/μl of DNA concentration and 10⁴ cfu/ml and 10⁸ cfu/ml of colony count, respectively. The LAMP assay was 10- and 10⁴-fold more sensitive than PCR using DNA concentration and colony count, respectively. The LAMP assay was found to be specific for clinically important ACB complex species.

Significance of the study: The LAMP assay can be applied for early detection of significant species of the ACB complex from clinical samples and their carbapenem-resistant variants. Depending on the emerging pathogen and locally prevalent resistance genes, the LAMP assay can be modified for detection of colonization or infection by various resistant bugs.

Bioluminescent detection of isothermal DNA amplification in microfluidic generated droplets and artificial cells

Microfluidic droplet generation affords precise, low volume, high throughput opportunities for molecular diagnostics. Isothermal DNA amplification with bioluminescent detection is a fast, low-cost, highly specific molecular diagnostic technique that is triggerable by temperature. Combining loop-mediated isothermal nucleic acid amplification (LAMP) and bioluminescent assay in real time (BART), with droplet microfluidics, should enable high-throughput, low copy, sequence-specific DNA detection by simple light emission. Stable, uniform LAMP–BART droplets are generated with low cost equipment. The composition and scale of these droplets are controllable and the bioluminescent output during DNA amplification can be imaged and quantified. Furthermore these droplets are readily incorporated into encapsulated droplet interface bilayers (eDIBs), or artificial cells, and the bioluminescence tracked in real time for accurate quantification off chip. Microfluidic LAMP–BART droplets with high stability and uniformity of scale coupled with high throughput and low cost generation are suited to digital DNA quantification at low template concentrations and volumes, where multiple measurement partitions are required. The triggerable reaction in the core of eDIBs can be used to study the interrelationship of the droplets with the environment and also used for more complex chemical processing via a self-contained network of droplets, paving the way for smart soft-matter diagnostics.

Optimizing viral load suppression in Kenyan children on antiretroviral therapy (Opt4Kids)

Background

As many as 40% of the 1 million children living with HIV (CLHIV) receiving antiretroviral treatment (ART) in resource limited settings have not achieved viral suppression (VS). Kenya has a large burden of pediatric HIV with nearly 140,000 CLHIV. Feasible, scalable, and cost-effective approaches to ensure VS in CLHIV are urgently needed. The goal of this study is to determine the feasibility and impact of point-of-care (POC) viral load (VL) and targeted drug resistance mutation (DRM) testing to improve VS in children on ART in Kenya.

Methods

We are conducting a randomized controlled study to evaluate the use of POC VL and targeted DRM testing among 704 children aged 1-14 years on ART at health facilities in western Kenya. Children are randomized 1:1 to intervention (higher frequency POC VL and targeted DRM testing) vs. control (standard-of-care) arms and followed for 12 months. Our primary outcome is VS (VL < 1000 copies/mL) 12 months after enrollment by study arm. Secondary outcomes include time to VS and the impact of targeted DRM testing on VS. In addition, key informant interviews with patients and providers will generate an understanding of how the POC VL intervention functions. Finally, we will model the cost-effectiveness of POC VL combined with targeted DRM testing.

Discussion

This study will provide critical information on the impact of POC VL and DRM testing on VS among CLHIV on ART in a resource-limited setting and directly address the need to find approaches that maximize VS among children on ART.

Trials registration

NCT03820323.

Improved Enumeration of Weakly Fluorescent CD4+ T-lymphocytes by Confining Cells in a Spinning Sample Cartridge with a Helical Minichannel

The CD4 (cluster of differentiation 4) counting method is used to measure the number of CD4+ T-lymphocytes per microliter of blood and to evaluate the timing of the initiation of antiretroviral therapy as well as the effectiveness of treatment in patients with human immunodeficiency virus. We developed a three-dimensional helical minichannel-based sample cartridge in which a thread-like microgroove formed in the cylindrical surface and configured a particle-positioning and imaging system equipped with a single DC (direct current) motor that can be controlled by a smartphone application. Confinement and enrichment of CD4 cells within a sharp focal depth along the helical minichannel is accomplished by spinning the cylindrical sample cartridge at high speed before acquiring cell images and thus CD4+ cells with weak fluorescence intensity can be detected even in a channel much deeper than existing two-dimensional flat chambers without an autofocusing module. By detecting more cells in a larger sample volume, the accuracy of the CD4 cell count is improved by a factor of 5.8 with a channel of 500 μm depth and the precision is enhanced by a factor of 1.5 with a coefficient of variation of 2.6%.

Point-of-care viral load monitoring: outcomes from a decentralized HIV programme in Malawi

Introduction

Routinely monitoring the HIV viral load (VL) of people living with HIV (PLHIV) on anti‐retroviral therapy (ART) facilitates intensive adherence counselling and faster ART regimen switch when treatment failure is indicated. Yet standard VL‐testing in centralized laboratories can be time‐intensive and logistically difficult in low‐resource settings. This paper evaluates the outcomes of the first four years of routine VL‐monitoring using Point‐of‐Care technology, implemented by Médecins Sans Frontières (MSF) in rural clinics in Malawi.

Methods

We conducted a retrospective cohort analysis of patients eligible for routine VL‐ testing between 2013 and 2017 in four decentralized ART‐clinics and the district hospital in Chiradzulu, Malawi. We assessed VL‐testing coverage and the treatment failure cascade (from suspected failure (first VL>1000 copies/mL) to VL suppression post regimen switch). We used descriptive statistics and multivariate logistic regression to assess factors associated with suspected failure.

Results and Discussion

Among 21,400 eligible patients, VL‐testing coverage was 85% and VL suppression was found in 89% of those tested. In the decentralized clinics, 88% of test results were reviewed on the same day as blood collection, whereas in the district hospital the median turnaround‐time for results was 85 days. Among first‐line ART patients with suspected failure (N = 1544), 30% suppressed (VL<1000 copies/mL), 35% were treatment failures (confirmed by subsequent VL‐testing) and 35% had incomplete VL follow‐up. Among treatment failures, 80% (N = 540) were switched to a second‐line regimen, with a higher switching rate in the decentralized clinics than in the district hospital (86% vs. 67%, p < 0.01) and a shorter median time‐to‐switch (6.8 months vs. 9.7 months, p < 0.01). Similarly, the post‐switch VL‐testing rate was markedly higher in the decentralized clinics (61% vs. 26%, p < 0.01). Overall, 79% of patients with a post‐switch VL‐test were suppressed.

Conclusions

Viral load testing at the point‐of‐care in Chiradzulu, Malawi achieved high coverage and good drug regimen switch rates among those identified as treatment failures. In decentralized clinics, same‐day test results and shorter time‐to‐switch illustrated the game‐changing potential of POC‐based VL‐testing. Nevertheless, gaps were identified along all steps of the failure cascade. Regular staff training, continuous monitoring and creating demand are essential to the success of routine VL‐testing.

Full Dynamic Range Quantification using Loop-mediated Amplification (LAMP) by Combining Analysis of Amplification Timing and Variance between Replicates at Low Copy Number

Quantification of nucleic acid targets at low copy number is problematic with the limit of detection at 95 percent confidence predicted to be 3 molecules or higher for quantitative PCR. Conversely the accuracy of digital PCR is diminished at higher concentrations of template approaching 100 percent positive partitions, with the Poisson distribution showing that an average of only 3 molecules per partition represents an amplification frequency of greater than 95 percent. Therefore a full range of template concentrations cannot be quantified accurately with these methods alone without dilution. Here we report the development of quantification metrics for use with loop-mediated amplification (LAMP) as a bridge between concentrated and dilute template concentrations. The basis for this is that real-time monitoring of LAMP reactions either by bioluminescent reporting (BART) or by fluorescent dye binding shows increasing variation in timings between replicates at low copy number due to the LAMP amplification mechanism. This effect increases with decreasing copy number, closely associated with the amplification frequency. The use of an artificial template showed that the increasing variation is not linked to the use of displacement primers during the initiation of amplification and is therefore a fundamental feature of the LAMP initiation event. Quantification between 1 and 10 copies of a template was successfully achieved with a number of methods with a low number of replicates with the strongest correlation to timing variance. These ultra-quantification methods for LAMP amplification either singularly or in combination have potential in a full dynamic range quantification strategy based on LAMP, in a closed tube, undiluted sample molecular diagnostic.

Reduced False Positives and Improved Reporting of Loop-Mediated Isothermal Amplification using Quenched Fluorescent Primers

Loop-mediated isothermal amplification (LAMP) is increasingly used in molecular diagnostics as an alternative to PCR based methods. There are numerous reported techniques to detect the LAMP amplification including turbidity, bioluminescence and intercalating fluorescent dyes. In this report we show that quenched fluorescent labels on various LAMP primers can be used to quantify and detect target DNA molecules down to single copy numbers. By selecting different fluorophores, this method can be simply multiplexed. Moreover this highly specific LAMP detection technique can reduce the incidence of false positives originating from mispriming events. Attribution of these events to particular primers will help inform and improve LAMP primer design.

Field evaluation of near point of care Cepheid GeneXpert HIV-1 Qual for early infant diagnosis

Background

Access to point-of-care HIV testing shortens turn-around times, time to diagnosis and reduces loss to follow-up hence minimizing barriers to early linkage to care and treatment among HIV infected infants. Currently samples for early infant HIV diagnosis are sent to centralized testing facilities which are few and located only at specific regions in Kenya. However, there are Point of Care (POC) early infant diagnosis [EID] technologies elsewhere such as SAMBA and ALERE-Q that are yet to be evaluated in Kenya despite the urgent need for data to inform policy formulation regarding EID. The Cepheid GeneXpert HIV-1 Qual (GeneXpert) technology for POC EID offers a great opportunity to minimize HIV associated morbidity, mortality and loss to follow-up through decentralization of early infant HIV testing to the clinics. This technology also allows for same-day results thus facilitating prompt linkage to care.

Methods

We evaluated the GeneXpert HIV Qual EID POC in Homabay County against the standard of care platform, Roche CAP/CTM HIV-1 qualitative PCR, using dried blood spots (DBS). Between February—July 2016, DBS samples were collected from HIV exposed children <18 months of age enrolled in a cross-sectional study. Samples were collected by qualified nurse counselors, and were tested by trained technicians using field based GeneXpert and conventional laboratory based Roche CAP/CTM HIV-1 qualitative PCR. Sensitivity and specificity were determined.

Results

Overall, 3,814 mother/infant pairs were included in the study, out of which 921 infants were HIV exposed as per the mothers’ HIV status and based on the infant’s HIV rapid test. A total of 969 PCR tests were performed, out of which 30 (3.3%) infants were concordantly positive using both platforms. GeneXpert HIV-1 Qual yielded a sensitivity of 94.1% and specificity of 99.8% with an overall error rate of 0.7%.

Conclusion

Our findings show that GeneXpert HIV-1 Qual performs well compared to CAP/CTM using DBS samples, suggesting that this technology may be adopted in decentralized laboratories as a near POC device. It may contribute to prompt diagnosis of HIV exposed infants hence enabling early linkage to care, thus advancing further gains in EID.

Optimised LAMP allows single copy detection of 35Sp and NOSt in transgenic maize using Bioluminescent Assay in Real Time (BART)

Loop-mediated amplification (LAMP) has been widely used to amplify and hence detect nucleic acid target sequences from various pathogens, viruses and genetic modifications. Two distinct types of primer are required for LAMP; hairpin-forming LAMP and displacement. High specificity arises from this use of multiple primers, but without optimal conditions for LAMP, sensitivity can be poor. We confirm here the importance of LAMP primer design, concentrations and ratios for efficient LAMP amplification. We further show that displacement primers are non-essential to the LAMP reaction at certain concentrations providing accelerating loop primers are present. We investigate various methods to quantify DNA extracts from GM maize certified reference materials to calculate the target copy numbers of template presented to the LAMP reaction, and show that LAMP can amplify transgenic promoter/terminator sequences in DNA extracted from various maize GM events using primers designed to target the 35S promoter (35Sp) or NOS terminator (NOSt) sequences, detection with both bioluminescence in real-time (BART) and fluorescent methods. With prior denaturation and HPLC grade LAMP primers single copy detection was achieved, showing that optimised LAMP conditions can be combined with BART for single copy targets, with simple and cost efficient light detection electronics over fluorescent alternatives.

p24 revisited: a landscape review of antigen detection for early HIV diagnosis

: Despite major advances in HIV testing, early detection of infection at the point of care (PoC) remains a key challenge. Although rapid antibody PoC and laboratory-based nucleic acid amplification tests dominate the diagnostics market, the viral capsid protein p24 is recognized as an alternative early virological biomarker of infection. However, the detection of ultra-low levels of p24 at the PoC has proven challenging. Here we review the landscape of p24 diagnostics to identify knowledge gaps and barriers and help shape future research agendas. Five hundred and seventy-four research articles to May 2018 that propose or evaluate diagnostic assays for p24 were identified and reviewed. We give a brief history of diagnostic development, and the utility of p24 as a biomarker in different populations such as infants, the newly infected, those on preexposure prophylaxis and self-testers. We review the performance of commercial p24 assays and consider elements such as immune complex disruption, resource-poor settings, prevalence, and assay antibodies. Emerging and ultrasensitive assays are reviewed and show a number of promising approaches but further translation has been limited. We summarize studies on the health economic benefits of using antigen testing. Finally, we speculate on the future uses of high-performance p24 assays, particularly, if available in self-test format.

Brief Report: Point of Care Cryptococcal Antigen Screening: Pipetting Finger-Prick Blood Improves Performance of Immunomycologics Lateral Flow Assay

BACKGROUND

Cryptococcal antigen (CrAg) screening at the point of care could improve cryptococcal meningitis prevention where laboratory resources are limited. We evaluated the accuracy of Immunomycologics (IMMY, Norman, OK) CrAg lateral flow assay (LFA) using different techniques at point of care.

SETTING

Two tertiary-level hospitals in Johannesburg and a community health clinic in Soweto, South Africa.

METHODS

A case-control diagnostic validation study and a prospective clinic-based implementation study using the IMMY CrAg LFA on finger-prick blood. Accuracy, using direct application of LFA to sample, or pipette to transfer sample to diluent, and reading after 10 and 20 minutes, was compared with laboratory-based plasma testing.

RESULTS

The validation study tested 64 CrAg-positive and 152 CrAg-negative patients with no symptoms or signs of meningitis, identified by routine laboratory screening, recruited by convenience sampling. Consecutively diagnosed HIV-infected adults (n = 654) were included in the implementation study. Sensitivity was 82% and 20% when the LFA was read 10 minutes after direct application to finger-prick blood in the validation and implementation studies, respectively. Using a pipette to transfer blood and reading after 20 minutes improved sensitivity to 100%, while retaining 100% specificity, in both studies.

CONCLUSIONS

Although the IMMY CrAg LFA performs well when applied directly to finger-prick blood for diagnosing cryptococcal meningitis, this technique may not provide adequate volume to detect low concentrations of CrAg when screening asymptomatic patients. Using a pipette to transfer larger volumes of blood to diluent before CrAg LFA testing and reading results after 20 minutes is a more reliable point-of-care method.

A highly sensitive aptamer-based HIV reverse transcriptase detection assay

Although many new assays for HIV have been developed, several labs still use simple and reliable radioactivity-based reverse transcriptase (RT) nucleotide incorporation assays for detection and quantification. We describe here a new assay for detection and quantitation of HIV RT activity that is based on a high affinity DNA aptamer to RT. The aptamer is sequestered on 96-well plates where it can bind to RT and other constituents can be removed by extensive washing. Since the aptamer mimics a primer-template, upon radiolabeled nucleotide addition, bound RT molecules can extend the aptamer and the radioactive signal can be detected by standard methods. In addition to being procedurally simple, the assay demonstrated high sensitivity (detection limits for RT and virions were ≤6400 molecules (∼4 × 10^-8 units) and ∼100-300 virions, respectively) and was essentially linear over a range of at least 10⁴. Both wild type and drug-resistant forms of HIV-1 RT were detectable as was HIV-2 RT, although there were some modest differences in sensitivity.

Point of Care Diagnostics for HIV in Resource Limited Settings: An Overview

Human immunodeficiency virus (HIV) is a global health problem. Early diagnosis, rapid antiretroviral therapy (ART) initiation and monitoring of viral load are the key strategies for effective HIV management. Many people in resource limited settings where timely access to medical care is a challenge and healthcare infrastructure is poor have no access to laboratory facilities and diagnosis is dependent on the presence of point of care (POC) devices. POC instruments have shown to be easy to operate, maintain and transport and can easily be operated by less skilled health workers. Additionally, POC tests do not require laboratory technicians to operate. POC devices have resulted in a growing number of people testing for HIV and thereby receiving treatment early. In recent years, there has been great improvement in the development of POC technologies for early HIV diagnosis, HIV viral load and cluster of differentiation 4 (CD4) measurement. This review discusses POC technologies that are currently available and in the pipeline for diagnosing and monitoring HIV. We also give an overview of the technical and commercialization challenges in POC diagnostics for HIV.

Molecular Microbiology

Background

Nucleic acid (NA) amplification techniques are now commonly used to diagnose and manage patients with infectious diseases. The growth in the number of Food and Drug Administration–approved test kits and analyte-specific reagents has facilitated the use of this technology in clinical laboratories. Technological advances in NA amplification techniques, automation, NA sequencing, and multiplex analysis have reinvigorated the field and created new opportunities for growth. Simple, sample-in, answer-out molecular test systems are now widely available that can be deployed in a variety of laboratory and clinical settings. Molecular microbiology remains the leading area in molecular pathology in terms of both the numbers of tests performed and clinical relevance. NA-based tests have reduced the dependency of the clinical microbiology laboratory on more traditional antigen detection and culture methods and created new opportunities for the laboratory to impact patient care.

Content

This chapter reviews NA testing as it applies to specific pathogens or infectious disease syndromes, with a focus on those diseases for which NA testing is now considered the standard of care and highlights the unique challenges and opportunities that these tests present for clinical laboratories.

Nucleic acid purification from plants, animals and microbes in under 30 seconds

Nucleic acid amplification is a powerful molecular biology tool, although its use outside the modern laboratory environment is limited due to the relatively cumbersome methods required to extract nucleic acids from biological samples. To address this issue, we investigated a variety of materials for their suitability for nucleic acid capture and purification. We report here that untreated cellulose-based paper can rapidly capture nucleic acids within seconds and retain them during a single washing step, while contaminants present in complex biological samples are quickly removed. Building on this knowledge, we have successfully created an equipment-free nucleic acid extraction dipstick methodology that can obtain amplification-ready DNA and RNA from plants, animals, and microbes from difficult biological samples such as blood and leaves from adult trees in less than 30 seconds. The simplicity and speed of this method as well as the low cost and availability of suitable materials (e.g., common paper towelling), means that nucleic acid extraction is now more accessible and affordable for researchers and the broader community. Furthermore, when combined with recent advancements in isothermal amplification and naked eye DNA visualization techniques, the dipstick extraction technology makes performing molecular diagnostic assays achievable in limited resource settings including university and high school classrooms, field-based environments, and developing countries.

Point-of-care diagnostics to improve maternal and neonatal health in low-resource settings

Each day, approximately 830 women and 7400 newborns die from complications during pregnancy and childbirth. Improving maternal and neonatal health will require bringing rapid diagnosis and treatment to the point of care in low-resource settings. However, to date there are few diagnostic tools available that can be used at the point of care to detect the leading causes of maternal and neonatal mortality in low-resource settings. Here we review both commercially available diagnostics and technologies that are currently in development to detect the leading causes of maternal and neonatal mortality, highlighting key gaps in development where innovative design could increase access to technology and enable rapid diagnosis at the bedside.

Fast, Sensitive, and Quantitative Point-of-Care Platform for the Assessment of Drugs of Abuse in Urine, Serum, and Whole Blood

Drug abuse is a major public health problem in many countries in Europe and North America. Currently available platforms for drug abuse assessment are facing technical challenges of nonquantitation, inaccuracy, low throughput, incompatibility with diverse complex specimens, long assay times, and requirement of instrument and/or expertise for readout. Here, we report an integrated competitive volumetric-bar-chart chip (CV-Chip) to assay multiple drug targets at the point-of-care (POC). To the best of our knowledge, it is the first time that a POC platform has been demonstrated to fully address the above-mentioned limitations. We applied this integrated CV-chip platform to assay multiple drugs in 38 patient urine and serum samples and validated the on-chip results with an LC-MS/MS method, indicating a clinical sensitivity and specificity of 0.94 and 1.00, respectively. We further demonstrated that the combination of an on-chip blood separator with the CV-Chip enabled the platform to directly assay finger-prick whole blood samples, which have always been recognized as an ideal biospecimen for POC detections. In summary, this integrated CV-Chip is able to serve as a sensitive, accurate, fast, portable, readout visible, and minimally invasive platform for drug abuse assessment.

GeneXpert HIV-1 quant assay, a new tool for scale up of viral load monitoring in the success of ART programme in India

BACKGROUND

Recent WHO guidelines identify virologic monitoring for diagnosing and confirming ART failure. In view of this, validation and scale up of point of care viral load technologies is essential in resource limited settings.

METHODS

A systematic validation of the GeneXpert® HIV-1 Quant assay (a point-of-care technology) in view of scaling up HIV-1 viral load in India to monitor the success of national ART programme was carried out. Two hundred nineteen plasma specimens falling in nine viral load ranges (<40 to >5 L copies/ml) were tested by the Abbott m2000rt Real Time and GeneXpert HIV-1 Quant assays. Additionally, 20 seronegative; 16 stored specimens and 10 spiked controls were also tested. Statistical analysis was done using Stata/IC and sensitivity, specificity, PPV, NPV and %misclassification rates were calculated as per DHSs/AISs, WHO, NACO cut-offs for virological failure.

RESULTS

The GeneXpert assay compared well with the Abbott assay with a higher sensitivity (97%), specificity (97-100%) and concordance (91.32%). The correlation between two assays (r = 0.886) was statistically significant (p < 0.01), the linear regression showed a moderate fit (R² = 0.784) and differences were within limits of agreement. Reproducibility showed an average variation of 4.15 and 3.52% while Lower limit of detection (LLD) and Upper limit of detection (ULD) were 42 and 1,740,000 copies/ml respectively. The misclassification rates for three viral load cut offs were not statistically different (p = 0.736). All seronegative samples were negative and viral loads of the stored samples showed a good fit (R² = 0.896 to 0.982).

CONCLUSION

The viral load results of GeneXpert HIV-1 Quant assay compared well with Abbott HIV-1 m2000 Real Time PCR; suggesting its use as a Point of care assay for viral load estimation in resource limited settings. Its ease of performance and rapidity will aid in timely diagnosis of ART failures, integrated HIV-TB management and will facilitate the UNAIDS 90-90-90 target.

A low-cost smartphone-based platform for highly sensitive point-of-care testing with persistent luminescent phosphors

Through their computational power and connectivity, smartphones are poised to rapidly expand telemedicine and transform healthcare by enabling better personal health monitoring and rapid diagnostics. Recently, a variety of platforms have been developed to enable smartphone-based point-of-care testing using imaging-based readout with the smartphone camera as the detector. Fluorescent reporters have been shown to improve the sensitivity of assays over colorimetric labels, but fluorescence readout necessitates incorporating optical hardware into the detection system, adding to the cost and complexity of the device. Here we present a simple, low-cost smartphone-based detection platform for highly sensitive luminescence imaging readout of point-of-care tests run with persistent luminescent phosphors as reporters. The extremely bright and long-lived emission of persistent phosphors allows sensitive analyte detection with a smartphone by a facile time-gated imaging strategy. Phosphors are first briefly excited with the phone's camera flash, followed by switching off the flash, and subsequent imaging of phosphor luminescence with the camera. Using this approach, we demonstrate detection of human chorionic gonadotropin using a lateral flow assay and the smartphone platform with strontium aluminate nanoparticles as reporters, giving a detection limit of ≈45 pg mL-1 (1.2 pM) in buffer. Time-gated imaging on a smartphone can be readily adapted for sensitive and potentially quantitative testing using other point-of-care formats, and is workable with a variety of persistent luminescent materials.

Detection of Acute and Early HIV-1 Infections in an HIV Hyper-Endemic Area with Limited Resources

BACKGROUND

Two thirds of the world's new HIV infections are in sub-Saharan Africa. Acute HIV infection (AHI) is the time of virus acquisition until the appearance of HIV antibodies. Early HIV infection, which includes AHI, is the interval between virus acquisition and establishment of viral load set-point. This study aimed to detect acute and early HIV infections in a hyper-endemic setting.

METHODS

This was a cross-sectional diagnostic study that enrolled individuals who had negative rapid HIV results in five clinics in South Africa. Pooled nucleic acid amplification testing (NAAT) was performed, followed by individual sample testing in positive pools. NAAT-positive participants were recalled to the clinics for confirmatory testing and appropriate management. HIV antibody, p24 antigen, Western Blot and avidity tests were performed for characterization of NAAT-positive samples.

RESULTS

The study enrolled 6910 individuals with negative rapid HIV results. Median age was 27 years (interquartile range {IQR}: 23-31). NAAT was positive in 55 samples, resulting in 0.8% newly diagnosed HIV-infected individuals (95% confidence interval {CI}: 0.6-1.0). The negative predictive value for rapid HIV testing was 99.2% (95% CI: 99.0-99.4). Characterization of NAAT-positive samples revealed that 0.04% (95% CI: 0.000-0.001) had AHI, 0.3% (95% CI: 0.1-0.4) had early HIV infection, and 0.5% (95% CI: 0.5-0.7) had chronic HIV infection. Forty-seven (86%) of NAAT-positive participants returned for follow-up at a median of 4 weeks (IQR: 2-8). Follow-up rapid tests were positive in 96% of these participants.

CONCLUSIONS

NAAT demonstrated that a substantial number of HIV-infected individuals are misdiagnosed at South African points-of-care. Follow-up rapid tests done within a 4 week interval detected early and chronic HIV infections initially missed by rapid HIV testing. This may be a practical and affordable strategy for earlier detection of these infections in resource-constrained settings. Newer molecular tests that can be used at the points-of-care should be evaluated for routine diagnosis of HIV in hyper-endemic settings.

Getting into the brain: Potential of nanotechnology in the management of NeuroAIDS

In spite of significant advances in antiretroviral (ARV) therapy, the elimination of human immunodeficiency virus (HIV) reservoirs from the periphery and the central nervous system (CNS) remains a formidable task. The incapability of ARV to go across the blood-brain barrier (BBB) after systemic administration makes the brain one of the dominant HIV reservoirs. Thus, screening, monitoring, and elimination of HIV reservoirs from the brain remain a clinically daunting and key task. The practice and investigation of nanomedicine possesses potentials for therapeutics against neuroAIDS. This review highlights the advancements in nanoscience and nanotechnology to design and develop specific size therapeutic cargo for efficient navigation across BBB so as to recognize and eradicate HIV brain reservoirs. Different navigation and drug release strategies, their biocompatibility and efficacy with related challenges and future prospects are also discussed. This review would be an excellent platform to understand nano-enable multidisciplinary research to formulate efficient nanomedicine for the management of neuroAIDS.

Performance Evaluation of the Becton Dickinson FACSPresto™ Near-Patient CD4 Instrument in a Laboratory and Typical Field Clinic Setting in South Africa

Background

The BD-FACSPresto^™ CD4 is a new, point-of-care (POC) instrument utilising finger-stick capillary blood sampling. This study evaluated its performance against predicate CD4 testing in South Africa.

Methods

Phase-I testing: HIV+ patient samples (n = 214) were analysed on the Presto^™ under ideal laboratory conditions using venous blood. During Phase-II, 135 patients were capillary-bled for CD4 testing on FACSPresto^™, performed according to manufacturer instruction. Comparative statistical analyses against predicate PLG/CD4 method and industry standards were done using GraphPad Prism 6. It included Bland-Altman with 95% limits of agreement (LOA) and percentage similarity with coefficient of variation (%CV) analyses for absolute CD4 count (cells/μl) and CD4 percentage of lymphocytes (CD4%).

Results

In Phase-I, 179/217 samples yielded reportable results with Presto^™ using venous blood filled cartridges. Compared to predicate, a mean bias of 40.4±45.8 (LOA of -49.2 to 130.2) and %similarity (%CV) of 106.1%±7.75 (7.3%) was noted for CD4 absolute counts. In Phase-2 field study, 118/135 capillary-bled Presto^™ samples resulted CD4 parameters. Compared to predicate, a mean bias of 50.2±92.8 (LOA of -131.7 to 232) with %similarity (%CV) 105%±10.8 (10.3%), and 2.87±2.7 (LOA of -8.2 to 2.5) with similarity of 94.7±6.5% (6.83%) noted for absolute CD4 and CD4% respectively. No significant clinical differences were indicated for either parameter using two sampling methods.

Conclusion

The Presto^™ produced remarkable precision to predicate methods, irrespective of venous or capillary blood sampling. A consistent, clinically insignificant over-estimation (5–7%) of counts against PLG/CD4 and equivalency to FACSCount^™ was noted. Further field studies are awaited to confirm longer-term use.

Genetic Variability of HIV-1 for Drug Resistance Assay Development

A hybridization-based point-of-care (POC) assay for HIV-1 drug resistance would be useful in low- and middle-income countries (LMICs) where resistance testing is not routinely available. The major obstacle in developing such an assay is the extreme genetic variability of HIV-1. We analyzed 27,203 reverse transcriptase (RT) sequences from the Stanford HIV Drug Resistance Database originating from six LMIC regions. We characterized the variability in a 27-nucleotide window surrounding six clinically important drug resistance mutations (DRMs) at positions 65, 103, 106, 181, 184, and 190. The number of distinct codons at each DRM position ranged from four at position 184 to 11 at position 190. Depending on the mutation, between 11 and 15 of the 24 flanking nucleotide positions were variable. Nonetheless, most flanking sequences differed from a core set of 10 flanking sequences by just one or two nucleotides. Flanking sequence variability was also lower in each LMIC region compared with overall variability in all regions. We also describe an online program that we developed to perform similar analyses for mutations at any position in RT, protease, or integrase.

The HIV Treatment Gap: Estimates of the Financial Resources Needed versus Available for Scale-Up of Antiretroviral Therapy in 97 Countries from 2015 to 2020

BACKGROUND

The World Health Organization (WHO) released revised guidelines in 2015 recommending that all people living with HIV, regardless of CD4 count, initiate antiretroviral therapy (ART) upon diagnosis. However, few studies have projected the global resources needed for rapid scale-up of ART. Under the Health Policy Project, we conducted modeling analyses for 97 countries to estimate eligibility for and numbers on ART from 2015 to 2020, along with the facility-level financial resources required. We compared the estimated financial requirements to estimated funding available.

METHODS AND FINDINGS

Current coverage levels and future need for treatment were based on country-specific epidemiological and demographic data. Simulated annual numbers of individuals on treatment were derived from three scenarios: (1) continuation of countries' current policies of eligibility for ART, (2) universal adoption of aspects of the WHO 2013 eligibility guidelines, and (3) expanded eligibility as per the WHO 2015 guidelines and meeting the Joint United Nations Programme on HIV/AIDS "90-90-90" ART targets. We modeled uncertainty in the annual resource requirements for antiretroviral drugs, laboratory tests, and facility-level personnel and overhead. We estimate that 25.7 (95% CI 25.5, 26.0) million adults and 1.57 (95% CI 1.55, 1.60) million children could receive ART by 2020 if countries maintain current eligibility plans and increase coverage based on historical rates, which may be ambitious. If countries uniformly adopt aspects of the WHO 2013 guidelines, 26.5 (95% CI 26.0 27.0) million adults and 1.53 (95% CI 1.52, 1.55) million children could be on ART by 2020. Under the 90-90-90 scenario, 30.4 (95% CI 30.1, 30.7) million adults and 1.68 (95% CI 1.63, 1.73) million children could receive treatment by 2020. The facility-level financial resources needed for scaling up ART in these countries from 2015 to 2020 are estimated to be US$45.8 (95% CI 45.4, 46.2) billion under the current scenario, US$48.7 (95% CI 47.8, 49.6) billion under the WHO 2013 scenario, and US$52.5 (95% CI 51.4, 53.6) billion under the 90-90-90 scenario. After projecting recent external and domestic funding trends, the estimated 6-y financing gap ranges from US$19.8 billion to US$25.0 billion, depending on the costing scenario and the U.S. President's Emergency Plan for AIDS Relief contribution level, with the gap for ART commodities alone ranging from US$14.0 to US$16.8 billion. The study is limited by excluding above-facility and other costs essential to ART service delivery and by the availability and quality of country- and region-specific data.

CONCLUSIONS

The projected number of people receiving ART across three scenarios suggests that countries are unlikely to meet the 90-90-90 treatment target (81% of people living with HIV on ART by 2020) unless they adopt a test-and-offer approach and increase ART coverage. Our results suggest that future resource needs for ART scale-up are smaller than stated elsewhere but still significantly threaten the sustainability of the global HIV response without additional resource mobilization from domestic or innovative financing sources or efficiency gains. As the world moves towards adopting the WHO 2015 guidelines, advances in technology, including the introduction of lower-cost, highly effective antiretroviral regimens, whose value are assessed here, may prove to be "game changers" that allow more people to be on ART with the resources available.

Integrated Microfluidic Nucleic Acid Isolation, Isothermal Amplification, and Amplicon Quantification

Microfluidic components and systems for rapid (<60 min), low-cost, convenient, field-deployable sequence-specific nucleic acid-based amplification tests (NAATs) are described. A microfluidic point-of-care (POC) diagnostics test to quantify HIV viral load from blood samples serves as a representative and instructive example to discuss the technical issues and capabilities of “lab on a chip” NAAT devices. A portable, miniaturized POC NAAT with performance comparable to conventional PCR (polymerase-chain reaction)-based tests in clinical laboratories can be realized with a disposable, palm-sized, plastic microfluidic chip in which: (1) nucleic acids (NAs) are extracted from relatively large (~mL) volume sample lysates using an embedded porous silica glass fiber or cellulose binding phase (“membrane”) to capture sample NAs in a flow-through, filtration mode; (2) NAs captured on the membrane are isothermally (~65 °C) amplified; (3) amplicon production is monitored by real-time fluorescence detection, such as with a smartphone CCD camera serving as a low-cost detector; and (4) paraffin-encapsulated, lyophilized reagents for temperature-activated release are pre-stored in the chip. Limits of Detection (LOD) better than 10³ virons/sample can be achieved. A modified chip with conduits hosting a diffusion-mode amplification process provides a simple visual indicator to readily quantify sample NA template. In addition, a companion microfluidic device for extracting plasma from whole blood without a centrifuge, generating cell-free plasma for chip-based molecular diagnostics, is described. Extensions to a myriad of related applications including, for example, food testing, cancer screening, and insect genotyping are briefly surveyed.

Using BD Vacutainer CD4 Stabilization Tubes for Absolute Cluster of Differentiation Type 4 Cell Count Measurement on BD FacsCount and Partec Cyflow Cytometers: A Method Comparison Study from Zimbabwe

Background

Blood collected in conventional EDTA tubes requires laboratory analysis within 48 hours to provide valid CD4 cell count results. This restricts access to HIV care for patients from rural areas in resource-constraint settings due to sample transportation problems. Stabilization Tubes with extended storage duration have been developed but not yet evaluated comprehensively.

Objective

To investigate stability of absolute CD4 cell count measurement of samples in BD Vacutainer CD4 Stabilization Tubes over the course of 30 days.

Methods

This was a laboratory-based method comparison study conducted at a rural district hospital in Beitbridge, Zimbabwe. Whole peripheral blood from 88 HIV positive adults was drawn into BD Vacutainer CD4 Stabilization Tubes and re-tested 1, 2, 3, 5, 7, 14 and 30 days after collection on BD FacsCount and Partec Cyflow cytometers in parallel. Absolute CD4 cell levels were compared to results from paired samples in EDTA tubes analysed on BD FacsCount at the day of sample collection (references methodology). Bland-Altman analysis based on ratios of the median CD4 counts was used, with acceptable variation ranges for Limits of Agreements of +/-20%.

Results

Differences in ratios of the medians remained below 10% until day 21 on BD FacsCount and until day 5 on Partec Cyflow. Variations of Limits of Agreement were beyond 20% after day 1 on both cytometers. Specimen quality decreased steadily after day 5, with only 68% and 40% of samples yielding results on BD FacsCount and Partec Cyflow at day 21, respectively.

Conclusions

We do not recommend the use of BD Vacutainer CD4 Stabilization Tubes for absolute CD4 cell count measurement on BD FacsCount or Partec Cyflow due to large variation of results and decay of specimen quality. Alternative technologies for enhanced CD4 testing in settings with limited laboratory and sample transportation capacity still need to be developed.

Access to CD4 Testing for Rural HIV Patients: Findings from a Cohort Study in Zimbabwe

Background

CD4 cell count measurement remains an important diagnostic tool for HIV care in developing countries. Insufficient laboratory capacity in rural Sub-Saharan Africa is frequently mentioned but data on the impact at an individual patient level are lacking. Urban-rural discrepancies in CD4 testing have not been quantified to date. Such evidence is crucial for public health planning and to justify new yet more expensive diagnostic procedures that could circumvent access constraints in rural areas.

Objective

To compare CD4 testing among rural and urban HIV patients during the first year of treatment.

Methods

Records from 2,145 HIV positive adult patients from a Médecins sans Frontières (Doctors without Borders) HIV project in Beitbridge, Zimbabwe, during 2011 and 2012 were used for a retrospective cohort analysis. Covariate-adjusted risk ratios were calculated to estimate the effects of area of residence on CD4 testing at treatment initiation, six and 12 months among rural and urban patients.

Findings

While the proportion of HIV patients returning for medical consultations at six and 12 months decreased at a similar rate in both patient groups, CD4 testing during consultations dropped to 21% and 8% for urban, and 2% and 1% for rural patients at six and 12 months, respectively. Risk ratios for missing CD4 testing were 0.8 (95% CI 0.7-0.9), 9.2 (95% CI 5.5-15.3), and 7.6 (95% 3.7-17.1) comparing rural versus urban patients at treatment initiation, six and 12 months, respectively.

Conclusions

CD4 testing was low overall, and particularly poor in rural patients. Difficulties with specimen transportation were probably a major factor underlying this difference and requires new diagnostic approaches. Our findings point to severe health system constraints in providing CD4 testing overall that need to be addressed if effective monitoring of HIV patients is to be achieved, whether by alternative CD4 diagnostics or newly-recommended routine viral load testing.

Near patient CD4 count in a hospitalized HIV patient population

BACKGROUND

Point-of-care (POC) CD4 T-cell counting is increasingly recognized as providing improved linkage-to-care during management of HIV infection, particularly in resource-limited settings where disease burden is highest. This study evaluated prototype POC CD4 T-cell counters from MBio Diagnostics in the context of low CD4 count, hospitalized patients in Mozambique. This study measured system performance when presented with challenging, low count samples from HIV/AIDS patients with acute illnesses resulting in hospitalization.

METHODS

Forty whole blood samples were collected from donors on the medical service at Maputo Central Hospital and absolute CD4 counts were generated on the MBio CD4 system and a reference laboratory using flow cytometry.

RESULTS

The mean and median CD4 counts by the flow cytometry reference were 173 and 80 cells/µL, respectively. Correlation between the MBio CD4 System and the reference was good. Bland-Altman analysis showed a mean bias of +15 cells/µL (+9 to +21 cells/µL, 95% CI), and limits of agreement of -47 to 77 cells/µL. For samples with counts >100 cells/µL (N = 14), the mean coefficient of variation was 7.3%. For samples with counts <50 cells/µL, mean absolute bias of replicate samples was 4.8 cells/µL. When two MBio readers were compared, Bland-Altman bias was -4 cells/µL (-13 to +6 cells/µL, 95% CI), and limits of agreement of -63 and +55 cells/µL.

CONCLUSIONS

The MBio System holds promise as a POC system for quantitation of CD4 T cells in resource-limited settings given system throughput (80-100 cartridges/day), design simplicity, and ease-of-use. © 2015 International Clinical Cytometry Society.

Ion concentration polarization on paper-based microfluidic devices and its application to preconcentrate dilute sample solutions

Microfluidic paper-based analytical devices (μPADs) are a promising solution for a wide range of point-of-care applications. The feasibility of inducing ion concentration polarization (ICP) on μPADs has thus far attracted little attention. Accordingly, this study commences by demonstrating the ICP phenomenon in a μPAD with a Nafion ion-selective membrane. We are the first to measure the current-voltage curve on a Nafion-coated μPAD in order to indicate that the ion depletion occurs and the ICP is triggered when the current reaches the limiting current. The ICP effect is then exploited to preconcentrate fluorescein on μPADs incorporating straight and convergent channels. By an optimal geometric design, it is shown that the convergent channel results in a greater preconcentration effect than the straight channel. Specifically, a 20-fold enhancement in the sample concentration is achieved after 130 s given an initial concentration of [Formula: see text] M and an external potential of 50 V. By contrast, the straight channel yields only a 10-fold improvement in the concentration after 180 s. Further, the practical feasibility of the proposed convergent-channel μPAD is demonstrated using fluorescein isothiocyanate labeled bovine serum albumin. The experimental results show that a 15-fold enhancement of the initial sample concentration ([Formula: see text] M) is obtained after 120 s given an external potential of 50 V.

HIV in children in a general population sample in East Zimbabwe: prevalence, causes and effects

Background

There are an estimated half-million children living with HIV in sub-Saharan Africa. The predominant source of infection is presumed to be perinatal mother-to-child transmission, but general population data about paediatric HIV are sparse. We characterise the epidemiology of HIV in children in sub-Saharan Africa by describing the prevalence, possible source of infection, and effects of paediatric HIV in a southern African population.

Methods

From 2009 to 2011, we conducted a household-based survey of 3389 children (aged 2–14 years) in Manicaland, eastern Zimbabwe (response rate: 73.5%). Data about socio-demographic correlates of HIV, risk factors for infection, and effects on child health were analysed using multi-variable logistic regression. To assess the plausibility of mother-to-child transmission, child HIV infection was linked to maternal survival and HIV status using data from a 12-year adult HIV cohort.

Results

HIV prevalence was (2.2%, 95% CI: 1.6–2.8%) and did not differ significantly by sex, socio-economic status, location, religion, or child age. Infected children were more likely to be underweight (19.6% versus 10.0%, p = 0.03) or stunted (39.1% versus 30.6%, p = 0.04) but did not report poorer physical or psychological ill-health. Where maternal data were available, reported mothers of 61/62 HIV-positive children were deceased or HIV-positive. Risk factors for other sources of infection were not associated with child HIV infection, including blood transfusion, vaccinations, caring for a sick relative, and sexual abuse. The observed flat age-pattern of HIV prevalence was consistent with UNAIDS estimates which assumes perinatal mother-to-child transmission, although modelled prevalence was higher than observed prevalence. Only 19/73 HIV-positive children (26.0%) were diagnosed, but, of these, 17 were on antiretroviral therapy.

Conclusions

Childhood HIV infection likely arises predominantly from mother-to-child transmission and is associated with poorer physical development. Overall antiretroviral therapy uptake was low, with the primary barrier to treatment appearing to be lack of diagnosis.

Molecular oncology testing in resource-limited settings

Cancer prevalence and mortality are high in developing nations, where resources for cancer control are inadequate. Nearly one-quarter of cancers in resource-limited nations are infection related, and molecular assays can capitalize on this relationship by detecting pertinent pathogen genomes and human gene variants to identify those at highest risk for progression to cancer, to classify lesions, to predict effective therapy, and to monitor tumor burden over time. Prime examples are human papillomavirus in cervical neoplasia, Helicobacter pylori and Epstein-Barr virus in gastric adenocarcinoma and lymphoma, and hepatitis B or C virus in hepatocellular cancer. Research is underway to engineer devices that overcome social, economic, and technical barriers limiting effective laboratory support. Additional challenges include an educated workforce, infrastructure for quality metrics and record keeping, and funds to sustain molecular test services. The combination of well-designed interfaces, novel and robust electrochemical technology, and telemedicine tools will promote adoption by frontline providers. Fast turnaround is crucial for surmounting loss to follow-up, although increased use of cell phones, even in rural areas, enhances options for patient education and engagement. Links to a broadband network facilitate consultation and centralized storage of medical data. Molecular technology shows promise to address gaps in health care through rapid, user-friendly, and cost-effective devices reflecting clinical priorities in resource-poor areas.

Current perspectives on HIV-1 antiretroviral drug resistance

Current advancements in antiretroviral therapy (ART) have turned HIV-1 infection into a chronic and manageable disease. However, treatment is only effective until HIV-1 develops resistance against the administered drugs. The most recent antiretroviral drugs have become superior at delaying the evolution of acquired drug resistance. In this review, the viral fitness and its correlation to HIV-1 mutation rates and drug resistance are discussed while emphasizing the concept of lethal mutagenesis as an alternative therapy. The development of resistance to the different classes of approved drugs and the importance of monitoring antiretroviral drug resistance are also summarized briefly.