Rapid Identification of SARS-CoV-2 Variants of Concern Using a Portable peakPCR Platform.

The need for tools that facilitate rapid detection and continuous monitoring of SARS-CoV-2 variants of concern (VOCs) is greater than ever, as these variants are more transmissible and therefore increase the pressure of COVID-19 on healthcare systems. To address this demand, we aimed at developing and evaluating a robust and fast diagnostic approach for the identification of SARS-CoV-2 VOC-associated spike gene mutations. Our diagnostic assays detect the E484K and N501Y single-nucleotide polymorphisms (SNPs) as well as a spike gene deletion (HV69/70) and can be run on standard laboratory equipment or on the portable rapid diagnostic technology platform peakPCR. The assays achieved excellent diagnostic performance when tested with RNA extracted from culture-derived SARS-CoV-2 VOC lineages and clinical samples collected in Equatorial Guinea, Central-West Africa. Simplicity of usage and the relatively low cost are advantages that make our approach well suitable for decentralized and rapid testing, especially in resource-limited settings.

Correction: Development and evaluation of PlasmoPod: A cartridge-based nucleic acid amplification test for rapid malaria diagnosis and surveillance.

[This corrects the article DOI: 10.1371/journal.pgph.0001516.].

Development and evaluation of PlasmoPod: A cartridge-based nucleic acid amplification test for rapid malaria diagnosis and surveillance.

Malaria surveillance is hampered by the widespread use of diagnostic tests with low sensitivity. Adequate molecular malaria diagnostics are often only available in centralized laboratories. PlasmoPod is a novel cartridge-based nucleic acid amplification test for rapid, sensitive, and quantitative detection of malaria parasites. PlasmoPod is based on reverse-transcription quantitative polymerase chain reaction (RT-qPCR) of the highly abundant Plasmodium spp. 18S ribosomal RNA/DNA biomarker and is run on a portable qPCR instrument which allows diagnosis in less than 30 minutes. Our analytical performance evaluation indicates that a limit-of-detection as low as 0.02 parasites/µL can be achieved and no cross-reactivity with other pathogens common in malaria endemic regions was observed. In a cohort of 102 asymptomatic individuals from Bioko Island with low malaria parasite densities, PlasmoPod accurately detected 83 cases, resulting in an overall detection rate of 81.4%. Notably, there was a strong correlation between the Cq values obtained from the reference RT-qPCR assay and those obtained from PlasmoPod. In an independent cohort, using dried blood spots from malaria symptomatic children living in the Central African Republic, we demonstrated that PlasmoPod outperforms malaria rapid diagnostic tests based on the PfHRP2 and panLDH antigens as well as thick blood smear microscopy. Our data suggest that this 30-minute sample-to-result RT-qPCR procedure is likely to achieve a diagnostic performance comparable to a standard laboratory-based RT-qPCR setup. We believe that the PlasmoPod rapid NAAT could enable widespread accessibility of high-quality and cost-effective molecular malaria surveillance data through decentralization of testing and surveillance activities, especially in elimination settings.

YestroSens, a field-portable S. cerevisiae biosensor device for the detection of endocrine-disrupting chemicals: Reliability and stability.

Farming, industry and urbanization lead to increases in the concentrations of potentially harmful compounds in waste, surface and drinking waters. One example of such pollution are estrogens, the steroidal female reproductive hormones. Already at a few nanograms per litre, these hormones can trigger endocrine disruption and cause acute and chronic health problems in humans and wildlife. Here, we present a Saccharomyces cerevisiae estrogen biosensor capable of detecting estradiol, as well as ethinylestradiol, at concentrations of 1 nM. After an initial characterization of the sensor strain performance in an optimal laboratory setting, we focused on developing a biosensor device. We addressed current limitations of biosensors, such as the requirement of the cells for a liquid growth matrix, controlled storage conditions required to preserve cell viability, and the usually required bulky, as well as expensive, laboratory equipment. Our study provides significant new insights into the field of applied biosensors. The system presented in this work takes microorganism-based analytics one step closer to field application in decentralized locations.