Environmental Monitoring for Biological Threat Agents Using the Autonomous Pathogen Detection System with Multiplexed Polymerase Chain Reaction

Sentinel cells programmed to respond to environmental DNA including human sequences

Monitoring environmental DNA can track the presence of organisms, from viruses to animals, but requires continuous sampling of transient sequences from a complex milieu. Here we designed living sentinels using Bacillus subtilis to report the uptake of a DNA sequence after matching it to a preencoded target. Overexpression of ComK increased DNA uptake 3,000-fold, allowing for femtomolar detection in samples dominated by background DNA. This capability was demonstrated using human sequences containing single-nucleotide polymorphisms (SNPs) associated with facial features. Sequences were recorded with high efficiency and were protected from nucleases for weeks. The SNP could be determined by sequencing or in vivo using CRISPR interference to turn on reporter expression in response to a specific base. Multiple SNPs were recorded by one cell or through a consortium in which each member recorded a different sequence. Sentinel cells could surveil for specific sequences over long periods of time for applications spanning forensics, ecology and epidemiology.

Environmental monitoring for filamentous fungal pathogens in hematopoietic cell transplant units

The incidence of invasive fungal disease (IFD) is on the rise due to increasing numbers of highly immunocompromized patients. Nosocomial IFD remains common despite our better understanding of its risk factors and pathophysiology. High-efficiency particulate air filtration with or without laminar air flow, frequent air exchanges, a positive pressure care environment, and environmental hygiene, amongst other measures, have been shown to reduce the mould burden in the patient environment. Environmental monitoring for moulds in areas where high-risk patients are cared for, such as hematopoietic cell transplant units, has been considered an adjunct to other routine environmental precautions. As a collaborative effort between authors affiliated to the Infection Prevention and Control Working Group and the Fungal Infection Working Group of the International Society of Antimicrobial Chemotherapy (ISAC), we reviewed the English language literature and international guidance to describe the evidence behind the need for environmental monitoring for filamentous fungi as a quality assurance approach with an emphasis on required additional precautions during periods of construction. Many different clinical sampling approaches have been described for air, water, and surface sampling with significant variation in laboratory methodologies between reports. Importantly, there are no agreed-upon thresholds that correlate with an increase in the clinical risk of mould infections. We highlight important areas for future research to assure a safe environment for highly immunocompromized patients.

Lab-on-a-chip technology for in situ combined observations in oceanography

The oceans sustain the global environment and diverse ecosystems through a variety of biogeochemical processes and their complex interactions. In order to understand the dynamism of the local or global marine environments, multimodal combined observations must be carried out in situ. On the other hand, instrumentation of in situ measurement techniques enabling biological and/or biochemical combined observations is challenging in aquatic environments, including the ocean, because biochemical flow analyses require a more complex configuration than physicochemical electrode sensors. Despite this technical hurdle, in situ analyzers have been developed to measure the concentrations of seawater contents such as nutrients, trace metals, and biological components. These technologies have been used for cutting-edge ocean observations to elucidate the biogeochemical properties of water mass with a high spatiotemporal resolution. In this context, the contribution of lab-on-a-chip (LoC) technology toward the miniaturization and functional integration of in situ analyzers has been gaining momentum. Due to their mountability, in situ LoC technologies provide ideal instrumentation for underwater analyzers, especially for miniaturized underwater observation platforms. Consequently, the appropriate combination of reliable LoC and underwater technologies is essential to realize practical in situ LoC analyzers suitable for underwater environments, including the deep sea. Moreover, the development of fundamental LoC technologies for underwater analyzers, which operate stably in extreme environments, should also contribute to in situ measurements for public or industrial purposes in harsh environments as well as the exploration of the extraterrestrial frontier.

The Concept of Making On-Chip Thermal Cycler for RT-PCR Using Conjugate Heat Transfer in Diverging Microchannel

Covid-19 is pandemic to which the world is fighting. Various precautionary measures are being imposed all over the world which is affecting the routine life of an individual and also the economy worldwide. Although, a definite vaccine is still not known to medical science but they are able to distinguish Covid-19 from the other types of flu. Presently this is being done by detecting the SARS-CoV-2 virus using RT-PCR technique as recommended by the World Health Organization (WHO) (WHO, Geneva, 2020). Reverse Transcription Polymerase Chain Reaction (RT-PCR) is a nucleic acid amplification test that converts the RNA into DNA and subsequently amplifies the specific DNA targets. This method was already being employed to detect the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) (Emery et al. in Emerg Infect Dis 10(2):311, 2004). The entire process of DNA amplification takes place in three steps: denaturation, annealing, and extension for which the sample is required to be maintained at constant temperatures of 95, 55 and 72 °C, respectively. This article introduces the technology to achieve a constant temperature which can be tweaked to develop on-chip RT-PCR.

A re-organizing biosurveillance framework based on fog and mobile edge computing

Biological threats are becoming a serious security issue for many countries across the world. Effective biosurveillance systems can primarily support appropriate responses to biological threats and consequently save human lives. Nevertheless, biosurveillance systems are costly to implement and hard to operate. Furthermore, they rely on static infrastructures that might not cope with the evolving dynamics of the monitored environment. In this paper, we present a reorganizing biosurveillance framework for the detection and localization of biological threats with fog and mobile edge computing support. In the proposed framework, a hierarchy of fog nodes are responsible for aggregating monitoring data within their regions and detecting potential threats. Although fog nodes are deployed on a fixed base station infrastructure, the framework provides an innovative technique for reorganizing the monitored environment structure to adapt to the evolving environmental conditions and to overcome the limitations of the static base station infrastructure. Evaluation results illustrate the ability of the framework to localize biological threats and detect infected areas. Moreover, the results show the effectiveness of the reorganization mechanisms in adjusting the environment structure to cope with the highly dynamic environment.

Identification of microbial key-indicators of oil contamination at sea through tracking of oil biotransformation: An Arctic field and laboratory study

In this paper, a molecular analytical approach for detecting hydrocarbonoclastic bacteria in water is suggested as a proxy measurement for tracking petroleum discharges in industrialized or pristine aquatic environments. This approach is tested for general application in cold marine regions (freezing to 5 °C). We used amplicon sequencing and qPCR to quantify 16S rRNA and GyrB genes from oleophilic bacteria in seawater samples from two different crude oil enrichments. The first experiment was conducted in a controlled environment using laboratory conditions and natural North Sea fjord seawater (NSC) at a constant temperature of 5 °C. The second was performed in the field with natural Arctic seawater (ARC) and outdoor temperature conditions from -7 °C to around 4 °C. Although the experimental conditions for NSC and ARC differed, the temporal changes in bacterial communities were comparable and reflected oil biotransformation processes. The common bacterial OTUs for NSC and ARC had the highest identity to Colwellia rossensis and Oleispira antarctica rRNA sequences and were enriched within a few days in both conditions. Other typical oil degrading bacteria such as Alcanivorax (n-alkane degrader) and Cycloclasticus (polycyclic aromatic hydrocarbons degrader) were rapidly enriched only in NSC conditions. Both the strong correlation between Oleispira SSU gene copies and oil concentration, and the specificity of the Oleispira assay suggest that this organism is a robust bioindicator for seawater contaminated by petroleum in cold water environments. Further optimization for automation of the Oleispira assay for in situ analysis with a genosensing device is underway. The assay for Colwellia quantification requires more specificity to fewer Colwellia OTUs and a well-established dose-response relationship before those taxa are used for oil tracking purposes.

A transcription aptasensor: amplified, label-free and culture-independent detection of foodborne pathogens via light-up RNA aptamers

We report a transcription aptasensor by using a light-up RNA aptamer. It allows for sensitive, label-free and culture-free detection of intact foodborne pathogens, and no separation, purification or enrichment processes are involved.

Detecting Biothreat Agents: From Current Diagnostics to Developing Sensor Technologies

Although a fundamental understanding of the pathogenicity of most biothreat agents has been elucidated and available treatments have increased substantially over the past decades, they still represent a significant public health threat in this age of (bio)terrorism, indiscriminate warfare, pollution, climate change, unchecked population growth, and globalization. The key step to almost all prevention, protection, prophylaxis, post-exposure treatment, and mitigation of any bioagent is early detection. Here, we review available methods for detecting bioagents including pathogenic bacteria and viruses along with their toxins. An introduction placing this subject in the historical context of previous naturally occurring outbreaks and efforts to weaponize selected agents is first provided along with definitions and relevant considerations. An overview of the detection technologies that find use in this endeavor along with how they provide data or transduce signal within a sensing configuration follows. Current "gold" standards for biothreat detection/diagnostics along with a listing of relevant FDA approved in vitro diagnostic devices is then discussed to provide an overview of the current state of the art. Given the 2014 outbreak of Ebola virus in Western Africa and the recent 2016 spread of Zika virus in the Americas, discussion of what constitutes a public health emergency and how new in vitro diagnostic devices are authorized for emergency use in the U.S. are also included. The majority of the Review is then subdivided around the sensing of bacterial, viral, and toxin biothreats with each including an overview of the major agents in that class, a detailed cross-section of different sensing methods in development based on assay format or analytical technique, and some discussion of related microfluidic lab-on-a-chip/point-of-care devices. Finally, an outlook is given on how this field will develop from the perspective of the biosensing technology itself and the new emerging threats they may face.

A simple and novel way of maintaining constant wall temperature in microdevices

Constant wall temperature /homogeneity in wall temperature is the need of various lab-on-chip devices employed in biological and chemical investigations. However method to maintain this condition does not seem to be available. In this work, a novel and simple way of maintaining constant wall temperature is proposed. A diverging microchannel along with conjugate effects is utilized towards this end. Both measurements and three dimensional numerical simulations are undertaken to prove the design. The investigation has been carried out over a large parameter range (divergence angle: 1–8°; length: 10–30 mm; depth: 86–200 μm; solid-to-fluid thickness ratio: 1.5–4.0, and solid-to-fluid thermal conductivity ratio: 27–646) and input conditions (mass flow rate: 4.17 × 10⁻⁵ −9.17 × 10⁻⁵ kg/s, heat flux: 2.4–9.6 W/cm²) which helped in establishing the finding. It is observed that a nearly constant wall temperature condition can be achieved over a large parameter range investigated. A model to arrive at the design parameter values is also proposed. The method is further demonstrated for series of microchannels where we successfully maintain each station at different temperature within ±1 °C. The finding is therefore significant and can be employed in both single and multi-stage processes such as PCR requiring different constant wall temperature with a fine resolution.

Metagenomic analysis of the airborne environment in urban spaces

The organisms in aerosol microenvironments, especially densely populated urban areas, are relevant to maintenance of public health and detection of potential epidemic or biothreat agents. To examine aerosolized microorganisms in this environment, we performed sequencing on the material from an urban aerosol surveillance program. Whole metagenome sequencing was applied to DNA extracted from air filters obtained during periods from each of the four seasons. The composition of bacteria, plants, fungi, invertebrates, and viruses demonstrated distinct temporal shifts. Bacillus thuringiensis serovar kurstaki was detected in samples known to be exposed to aerosolized spores, illustrating the potential utility of this approach for identification of intentionally introduced microbial agents. Together, these data demonstrate the temporally dependent metagenomic complexity of urban aerosols and the potential of genomic analytical techniques for biosurveillance and monitoring of threats to public health.

Quantitative and sensitive RNA based detection of Bacillus spores

The fast and reliable detection of bacterial spores is of great importance and still remains a challenge. Here we describe a direct RNA-based diagnostic method for the specific detection of viable bacterial spores which does not depends on an enzymatic amplification step and therefore is directly appropriate for quantification. The procedure includes the following steps: (i) heat activation of spores, (ii) germination and enrichment cultivation, (iii) cell lysis, and (iv) analysis of 16S rRNA in crude cell lysates using a sandwich hybridization assay. The sensitivity of the method is dependent on the cultivation time and the detection limit; it is possible to detect 10 spores per ml when the RNA analysis is performed after 6 h of enrichment cultivation. At spore concentrations above 10(6) spores per ml the cultivation time can be shortened to 30 min. Total analysis times are in the range of 2-8 h depending on the spore concentration in samples. The developed procedure is optimized at the example of Bacillus subtilis spores but should be applicable to other organisms. The new method can easily be modified for other target RNAs and is suitable for specific detection of spores from known groups of organisms.

Catch and release: integrated system for multiplexed detection of bacteria

An integrated system with automated immunomagnetic separation and processing of fluidic samples was demonstrated for multiplexed optical detection of bacterial targets. Mixtures of target-specific magnetic bead sets were processed in the NRL MagTrap with the aid of rotating magnet arrays that entrapped and moved the beads within the channel during reagent processing. Processing was performed in buffer and human serum matrixes with 10-fold dilutions in the range of 10(2)-10(6) cells/mL of target bacteria. Reversal of magnets' rotation post-processing released the beads back into the flow and moved them into the microflow cytometer for optical interrogation. Identification of the beads and the detection of PE fluorescence were performed simultaneously for multiplexed detection. Multiplexing was performed with specifically targeted bead sets to detect E. coli 0157.H7, Salmonella Common Structural Antigen, Listeria sp., and Shigella sp., dose-response curves were obtained, and limits of detection were calculated for each target in the buffer and clinical matrix. Additional tests demonstrated the potential for using the MagTrap to concentrate target from larger volumes of sample prior to the addition of assay reagents.

Point-of-Care Testing for Pandemic Influenza and Biothreats

New and reemerging infectious diseases, such as pandemic viruses and resistant bacteria, pose a serious threat in the 21st century. Some of these agents represent global security threats. This review provides an overview of diagnostic challenges presented by pandemic influenza and biothreat agents. The article summarizes recent pandemics and disease outbreaks, point-of-care influenza diagnostic tests, biothreat agents, biothreat instrument systems, and technologies in development. It highlights how medical innovation and health care initiatives can help prepare health care professionals and public health personnel to handle future crises. Based on gap analysis for current point-of-care testing deficiencies, it concludes with policy recommendations that will enhance preparedness. (Disaster Med Public Health Preparedness. 2009;3(Suppl 2):S193–S202)

Development and comparison of two assay formats for parallel detection of four biothreat pathogens by using suspension microarrays

Microarrays provide a powerful analytical tool for the simultaneous detection of multiple pathogens. We developed diagnostic suspension microarrays for sensitive and specific detection of the biothreat pathogens Bacillus anthracis, Yersinia pestis, Francisella tularensis and Coxiella burnetii. Two assay chemistries for amplification and labeling were developed, one method using direct hybridization and the other using target-specific primer extension, combined with hybridization to universal arrays. Asymmetric PCR products for both assay chemistries were produced by using a multiplex asymmetric PCR amplifying 16 DNA signatures (16-plex). The performances of both assay chemistries were compared and their advantages and disadvantages are discussed. The developed microarrays detected multiple signature sequences and an internal control which made it possible to confidently identify the targeted pathogens and assess their virulence potential. The microarrays were highly specific and detected various strains of the targeted pathogens. Detection limits for the different pathogen signatures were similar or slightly higher compared to real-time PCR. Probit analysis showed that even a few genomic copies could be detected with 95% confidence. The microarrays detected DNA from different pathogens mixed in different ratios and from spiked or naturally contaminated samples. The assays that were developed have a potential for application in surveillance and diagnostics.

Biosurveillance: a review and update

Since the terrorist attacks and anthrax release in 2001, almost $32 billion has been allocated to biodefense and biosurveillance in the USA alone. Surveillance in health care refers to the continual systematic collection, analysis, interpretation, and dissemination of data. When attempting to detect agents of bioterrorism, surveillance can occur in several ways. Syndromic surveillance occurs by monitoring clinical manifestations of certain illnesses. Laboratory surveillance occurs by looking for certain markers or laboratory data, and environmental surveillance is the process by which the ambient air or environment is continually sampled for the presence of biological agents. This paper focuses on the ways by which we detect bioterrorism agents and the effectiveness of these systems.

Underwater application of quantitative PCR on an ocean mooring

The Environmental Sample Processor (ESP) is a device that allows for the underwater, autonomous application of DNA and protein probe array technologies as a means to remotely identify and quantify, in situ, marine microorganisms and substances they produce. Here, we added functionality to the ESP through the development and incorporation of a module capable of solid-phase nucleic acid extraction and quantitative PCR (qPCR). Samples collected by the instrument were homogenized in a chaotropic buffer compatible with direct detection of ribosomal RNA (rRNA) and nucleic acid purification. From a single sample, both an rRNA community profile and select gene abundances were ascertained. To illustrate this functionality, we focused on bacterioplankton commonly found along the central coast of California and that are known to vary in accordance with different oceanic conditions. DNA probe arrays targeting rRNA revealed the presence of 16S rRNA indicative of marine crenarchaea, SAR11 and marine cyanobacteria; in parallel, qPCR was used to detect 16S rRNA genes from the former two groups and the large subunit RuBisCo gene (rbcL) from Synecchococcus. The PCR-enabled ESP was deployed on a coastal mooring in Monterey Bay for 28 days during the spring-summer upwelling season. The distributions of the targeted bacterioplankon groups were as expected, with the exception of an increase in abundance of marine crenarchaea in anomalous nitrate-rich, low-salinity waters. The unexpected co-occurrence demonstrated the utility of the ESP in detecting novel events relative to previously described distributions of particular bacterioplankton groups. The ESP can easily be configured to detect and enumerate genes and gene products from a wide range of organisms. This study demonstrated for the first time that gene abundances could be assessed autonomously, underwater in near real-time and referenced against prevailing chemical, physical and bulk biological conditions.

A sample-in-answer-out instrument for the detection of multiple respiratory pathogens in unprepared nasopharyngeal swab samples

Multiplex RT-PCR suspension array assays provide a powerful tool for identifying the causative agent(s) of respiratory infections. These assays are time consuming and laborious on a time-per-sample basis if only a few samples require processing. To address this shortcoming and provide an automated solution for fast detection and identification of viral pathogens, we developed the first automated multiplex RT-PCR suspension array instrument capable of handling unprepared clinical samples. The instrument requires less than 3 minutes of hands-on time for a result generated in approximately 2.5 hours. In analytical studies, the instrument performed as well as manually performed assays. The performance of the instrument and loaded multiplex viral detection assay was then tested using unprepared nasopharyngeal samples. The instrument-performed assay detected 61 of 71 RSV positive samples, for a sensitivity of 85.9%. Adenovirus (n = 5) and influenza B (n = 3) were less prevalent in the sample set, but detected to similar levels, 80% and 75%, respectively. The same sample set was also tested using FDA approved immuno-assay rapid tests, and the instrument was found to be more sensitive than the rapid tests with the sole exception being influenza A (n = 16), which was poorly detected due to significant sequence mismatches between the influenza A primer/probe set included in the multiplex mixture and the circulating influenza A strains. Overall, these data demonstrate the developed prototype platform performs multiplex array assays as well as hand-performed assays, and that the instrument's sensitivity and specificity are dictated by the quality of the loaded multiplex assay.