Comparison of automated and manual nucleic acid extraction methods for detection of enterovirus RNA

Evaluation of Commercial RNA Extraction Protocols for Avian Influenza Virus Using Nanopore Metagenomic Sequencing

Avian influenza virus (AIV) is a significant threat to the poultry industry, necessitating rapid and accurate diagnosis. The current AIV diagnostic process relies on virus identification via real-time reverse transcription-polymerase chain reaction (rRT-PCR). Subsequently, the virus is further characterized using genome sequencing. This two-step diagnostic process takes days to weeks, but it can be expedited by using novel sequencing technologies. We aim to optimize and validate nucleic acid extraction as the first step to establishing Oxford Nanopore Technologies (ONT) as a rapid diagnostic tool for identifying and characterizing AIV from clinical samples. This study compared four commercially available RNA extraction protocols using AIV-known-positive clinical samples. The extracted RNA was evaluated using total RNA concentration, viral copies as measured by rRT-PCR, and purity as measured by a 260/280 absorbance ratio. After NGS testing, the number of total and influenza-specific reads and quality scores of the generated sequences were assessed. The results showed that no protocol outperformed the others on all parameters measured; however, the magnetic particle-based method was the most consistent regarding CT value, purity, total yield, and AIV reads, and it was less error-prone. This study highlights how different RNA extraction protocols influence ONT sequencing performance.

A semi-automated and high-throughput approach for the detection of honey bee viruses in bee samples

Deformed wing virus (DWV) was first detected in dead honey bees in 1982 but has been in honey bees for at least 300 years. Due to its high prevalence and virulence, they have been linked with the ongoing decline in honey bee populations worldwide. A rapid, simple, semi-automated, high-throughput, and cost-effective method of screening colonies for viruses would benefit bee research and the beekeeping industry. Here we describe a semi-automated approach that combines an RNA-grade liquid homogenizer followed by magnetic bead capture for total virus nucleic acid extraction. We compare it to the more commonly applied nucleic acid column-based purification method and use qPCR plus Oxford Nanopore Technologies sequencing to evaluate the accuracy of analytical results for both methods. Our results showed high reproducibility and accuracy for both approaches. The semi-automated method described here allows for faster screening of viral loads in units of 96 samples at a time. We developed this method to monitor viral loads in honey bee colonies, but it could be easily applied for any PCR or genomic-based screening assays.

Comparison of Manual and Automated Nucleic Acid (RNA) Extraction Methods for the Detection of SARS-CoV-2 by qRT-PCR

Objectives During the COVID-19 pandemic, several laboratories used different RNA extraction methods based on the resources available. Hence this study was done to compare the Ct values in qRT-PCR, time taken (sample processing-loading to PCR), manpower requirement, and cost of consumables between manual and automated methods. Materials and methods A cross-sectional study was done on 120 nasopharyngeal/oropharyngeal swabs received in VRDL for RT-PCR testing. Based on the results of automated RNA extraction (Genetix, HT 96 Purifier) and RT-PCR (Trivitron PCR Kit) detecting E gene (screening) and ORF gene (confirmatory), the division into Group- I (Ct 15-22), Group- II (Ct 23-29), Group-III (Ct 30-36) and Group-IV (Ct >36) was done. Manual RNA extraction was done using magnetic beads (Lab system, Trivitron). Statistical analysis Data were analyzed by SPSS 19.0 version software. Ct values obtained in the two methods were compared by paired t-test, GroupWise. Z test was used to compare the other parameters. Results The difference in Ct values for target genes was statistically significant (p<0.05) in Group-I to III; however, no variation in result interpretation. The difference in time, manpower, and cost were statistically significant (p<0.05). The manual method required twice more manpower; 40 minutes more time & automated method cost 3.5 times more for consumables. Conclusion The study showed that RNA yield was better with automated extraction in comparison to manual extraction. The samples extracted by the automated method detected the virus at a lower Ct range by PCR than the manual method. Automated method processed samples in less time and with less manpower. Considering the cost factor, manual extraction can be preferred in resource-limited settings as there was no difference in the results of the test. The manual method requires more hands-on time with potential chances of cross-contamination and technical errors.

High-Throughput and Automated Detection of HLA-B*27 Using the LabTurboTM AIO System

The adoption of an automated system can decrease the hands-on time requirements in a clinical laboratory setting. For the detection of HLA-B*27, implementing a high-throughput and fully automated system has several advantages over using manual methods. Therefore, this study aimed to evaluate automation efficiency for the detection of HLA-B*27. Peripheral blood samples were obtained from 50 participants, and DNA was isolated from these samples. A Pharmigene PG27 detection kit was used for the qualitative detection of HLA-B*27. The performances of the semi-automated and fully automated LabTurbo^TM AIO systems in the detection of HLA-B*27 were compared. The mean absorbance (optical density) values for the Maelstrom^TM 8 and LabTurbo^TM AIO systems were found to be 1.88 and 1.9, respectively. The housekeeping gene was amplified and quantified using a real-time PCR assay across all DNA extracts to check the quality of the extracted human DNA. The results were expressed as the cycle threshold (Ct) values for all DNA extracts from both platforms. The mean Ct values for the Roche Cobas z480 and LabTurbo^TM AIO systems were found to be 22.7 and 20.4, respectively. This study demonstrated that the semi-automated method and the LabTurbo^TM AIO system yield consistent results for the detection of HLA-B*27. However, compared to the semi-automated method, the LabTurbo^TM AIO system provides standardized procedures, avoids manual handling, and improves turnaround time.

Direct capture and amplification of nucleic acids using a universal, elution-free magnetic bead-based method for rapid pathogen detection in multiple types of biological samples

Nucleic acid amplification tests (NAATs) have become an attractive approach for pathogen detection, and obtaining high-quality nucleic acid extracts from biological samples plays a critical role in ensuring accurate NAATs. In this work, we established an elution-free magnetic bead (MB)-based method by introducing polyethylene-polypropylene glycol (PEPPG) F68 in lysis buffer and using NaOH solution instead of alcohols as the washing buffer for rapid nucleic acid extraction from multiple types of biological samples, including nasopharyngeal swabs, serum, milk, and pork, which bypassed the nucleic acid elution step and allowed the nucleic acid/MB composite to be directly used as the template for amplification reactions. The entire extraction process was able to be completed in approximately 7 min. Even though the nucleic acid/MB composite could not be used for quantitative real-time PCR (qPCR) assays, this elution-free MB-based method significantly improved the sensitivity of the loop-mediated isothermal amplification (LAMP) assay. The sensitivity of the quantitative real-time LAMP (qLAMP) assays combined with this elution-free MB-based method showed an improvement of one to three orders of magnitude compared with qLAMP or qPCR assays combined with the traditional MB-based method. In addition to manual operation, like the traditional MB-based method, this universal, rapid, and facile nucleic acid extraction method also has potential for integration into automated robotic processing, making it particularly suitable for the establishment of an analysis platform for ultrafast and sensitive pathogen detection in various biological samples both in centralized laboratories and at remote sites.

Easy Express Extraction (TripleE)-A Universal, Electricity-Free Nucleic Acid Extraction System for the Lab and the Pen

The complexity of the current nucleic acid isolation methods limits their use outside of the modern laboratory environment. Here, we describe a fast and affordable method (easy express extraction, called TripleE) as a centrifugation-free and electricity-free nucleic acid isolation method. The procedure is based on the well-established magnetic-bead extraction technology using an in-house self-made magnetic 8-channel and a rod cover. With this extraction system, nucleic acids can be isolated with two simple and universal protocols. One method was designed for the extraction of the nucleic acid in resource-limited “easy labs”, and the other method can be used for RNA/DNA extraction in the field for so-called molecular “pen-side tests”. In both scenarios, users can extract up to 8 samples in 6 to 10 min, without the need for any electricity, centrifuges or robotic systems. In order to evaluate and compare both methods, clinical samples from various viruses (African swine fever virus; lumpy skin disease virus; peste des petits ruminants virus; bluetongue virus), matrices and animals were tested and compared with standard magnetic-bead nucleic acid extraction technology based on the KingFisher platform. Hence, validation data were generated by evaluating two DNA viruses as well as one single-stranded and one double-stranded RNA virus. The results showed that the fast, easy, portable and electricity-free extraction protocols allowed rapid and reliable nucleic acid extraction for a variety of viruses and most likely also for other pathogens, without a substantial loss of sensitivity compared to standard procedures. The speed and simplicity of the methods make them ideally suited for molecular applications, both within and outside the laboratory, including limited-resource settings.

Contribution of magnetic particles in molecular diagnosis of human viruses

Viral diseases are the primary source of death, making a worldwide influence on healthcare, social, and economic development. Thus, diagnosis is the vital approach to the main aim of virus control and elimination. On the other hand, the prompt advancement of nanotechnology in the field of medicine possesses the probability of being beneficial to diagnose infections normally in labs as well as specifically. Nanoparticles are efficiently in use to make novel strategies because of permitting analysis at cellular in addition to the molecular scale. Henceforth, they assist towards pronounced progress concerning molecular analysis at the nanoscale. In recent times, magnetic nanoparticles conjugated through covalent bonds to bioanalytes for instance peptides, antibodies, nucleic acids, plus proteins are established like nanoprobes aimed at molecular recognition. These modified magnetic nanoparticles could offer a simple fast approach for extraction, purification, enrichment/concentration, besides viruses' recognition precisely also specifically. In consideration of the above, herein insight and outlook into the limitations of conventional methods and numerous roles played by magnetic nanoparticles to extract, purify, concentrate, and additionally in developing a diagnostic regime for viral outbreaks to combat viruses especially the ongoing novel coronavirus (COVID-19).

COVID-19: A systematic review and update on prevention, diagnosis, and treatment

Since the rapid onset of the COVID-19 or SARS-CoV-2 pandemic in the world in 2019, extensive studies have been conducted to unveil the behavior and emission pattern of the virus in order to determine the best ways to diagnosis of virus and thereof formulate effective drugs or vaccines to combat the disease. The emergence of novel diagnostic and therapeutic techniques considering the multiplicity of reports from one side and contradictions in assessments from the other side necessitates instantaneous updates on the progress of clinical investigations. There is also growing public anxiety from time to time mutation of COVID-19, as reflected in considerable mortality and transmission, respectively, from delta and Omicron variants. We comprehensively review and summarize different aspects of prevention, diagnosis, and treatment of COVID-19. First, biological characteristics of COVID-19 were explained from diagnosis standpoint. Thereafter, the preclinical animal models of COVID-19 were discussed to frame the symptoms and clinical effects of COVID-19 from patient to patient with treatment strategies and in-silico/computational biology. Finally, the opportunities and challenges of nanoscience/nanotechnology in identification, diagnosis, and treatment of COVID-19 were discussed. This review covers almost all SARS-CoV-2-related topics extensively to deepen the understanding of the latest achievements (last updated on January 11, 2022).

Optimization of RNA storage in a biobank, as well as methods for manual and automated isolation of RNA from whole blood and leukocyte fraction

Aim. To optimize the technique for the isolation and storage of ribonucleic acid (RNA) from whole blood and leukocyte fraction.

Materials and methods. Comparison of isolation quality was carried out for RNA samples obtained from 228 leukocyte samples and 198 whole blood samples. Isolation was performed from fresh and frozen samples using ExtractRNA™ reagent and a MagNA Pure Compact automated system. Various methods of removing erythrocytes (centrifugation and treatment with hemolytic agents from two manufacturers) were tested, as well as freezing with and without preservatives for subsequent RNA isolation.

Results. Twenty-one combinations of conditions were tested. The highest quality RNA was isolated by manual extraction using the ExtractRNA™ reagent from a fresh leukocyte fraction, purified by the Amplisens hemolytic agent (successful extraction — 94%, median RIN=8,4); frozen in IntactRNA™, purified by leukocyte fraction centrifugation (successful extraction — 100%, median RIN=8); frozen in ExtractRNA™, purified by leukocyte fraction centrifugation (successful extraction — 100%, median RIN=9,3).

Conclusion. RNA can be isolated from frozen blood fractions, which is not inferior in quality to that isolated from fresh samples. Thus, it is not necessary to isolate RNA immediately after the receipt of biological material.

The Use of Flocked Swabs with a Protective Medium Increases the Recovery of Live Brucella spp. and DNA Detection

Brucellosis is a worldwide zoonosis caused by bacteria from the genus Brucella. Once established, it is very hard to eradicate this disease, since it contaminates animals, the environment, and humans, causing problems for veterinary and public health as well as wildlife protection programs. Swabs are used for sampling in bacteriological and/or molecular diagnostics, from seropositive animals with disease symptoms, from genitalia or tissue lesions, as well as from contaminated environments. The aim of this study was to compare main of the commercially used swab types for sampling and diagnostics of Brucella spp. and determine the optimal storage conditions and time frame for testing. To achieve this, we tested bacterial and molecular methods for detection of Brucella abortus, Brucella melitensis, and Brucella suis using nine swab types, all with different tip materials, treated immediately after spiking, after 72 h at +4°C, and after 72 h at −20°C. Flocked swabs showed the highest capacity to preserve bacterial viability and DNA quality, regardless the storage conditions. Flocked swabs immersed in a protective medium provided the best conditions for Brucella survival in all three storage conditions. At the same time, the efficacy of quantitative PCR (qPCR) detection for all swabs, including the positive control, was above 50%, irrespective of the storage conditions, while bacterial survival was significantly lowered when swabs were kept at +4°C or −20°C for 72 h (48.2% and 27.5%, respectively). Compared to the positive control and other types, the flocked swabs maintained higher reproducibility regarding their capacity to preserve live bacteria in all three storage conditions.

IMPORTANCE In order to protect public and veterinary health from highly zoonotic bacteria such as members of the genus Brucella and prevent their dissemination into the environment, direct diagnostics are of utmost importance. However, in addition to the highly specific diagnostic tests, the sampling methods, time necessary for specimens to reach the laboratories, and transport conditions are important factors to consider in order to increase the sensitivity of performed tests, especially bacterial culturing and qPCR. This paper shows how different swab types and storage conditions influence classical bacteriological diagnostics of the most prevalent Brucella species – B. melitensis, B. abortus, and B. suis – but have little impact on molecular methods. The presented results highlight (i) the choice of swab regarding the storage and transport conditions, (ii) the importance of immediate swab treatment upon sampling, and (iii) that molecular methods do not depend on storage conditions, unlike classical bacteriological isolation.

RNA Extraction from Equine Samples for Equine Influenza Virus

The primary goals of this chapter are to discuss common viral RNA isolation and purification methods that are routinely used by various diagnostic laboratories and to highlight the advantages and drawbacks of each method and to identify the most suitable and reliable method to increase the sensitivity and specificity of RT-PCR assays for the detection of equine influenza virus (EIV) in clinical specimens. Our experiences and review of literature show that magnetic bead-based nucleic extraction methods (manual and automatic) work well for isolation and purification of EIV RNA from nasal swab specimens. Furthermore, most of the information presented in this chapter could be directly applicable to isolation and purification of nucleic acids (both DNA and RNA) from other equine clinical samples.

Guidelines for Setting Up a mRNA Sequencing Experiment and Best Practices for Bioinformatic Data Analysis

RNA-sequencing, commonly referred to as RNA-seq, is the most recently developed method for the analysis of transcriptomes. It uses high-throughput next-generation sequencing technologies and has revolutionized our understanding of the complexity and dynamics of whole transcriptomes.In this chapter, we recall the key developments in transcriptome analysis and dissect the different steps of the general workflow that can be run by users to design and perform a mRNA-seq experiment as well as to process mRNA-seq data obtained by the Illumina technology. The chapter proposes guidelines for completing a mRNA-seq study properly and makes available recommendations for best practices based on recent literature and on the latest developments in technology and algorithms. We also remark the large number of choices available (especially for bioinformatic data analysis) in front of which the scientist may be in trouble.In the last part of the chapter we discuss the new frontiers of single-cell RNA-seq and isoform sequencing by long read technology.

External Quality Assessment for Molecular Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Clinical Laboratories

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a huge threat to public health. Viral nucleic acid testing is the diagnostic gold standard and can play an important role in the prevention and control of this infection. In this study, bacteriophage MS2 virus-like particles encapsulating specific RNA sequences of SARS-CoV-2 and other coronaviruses were prepared by genetic engineering. The assessment panel, consisting of four positive samples with concentrations of 2.8, 3.5, 4.2, and 4.9 log₁₀ copies/mL and five negative samples with other human coronaviruses, was prepared and distributed to evaluate the accuracy of routine viral RNA detection. Results of 931 panels from 844 laboratories were collected. The overall percentage agreement, positive percentage agreement (PPA), and negative percentage agreement, defined as the percentage of agreement between the correct results and total results submitted for all, positive, and negative samples were 96.8% (8109/8379), 93.9% (3497/3724), and 99.1% (4612/4655), respectively. For samples with concentrations of 4.9 and 4.2 log₁₀ copies/mL, the PPAs were >95%. However, for 3.5 and 2.8 log₁₀ copies/mL, the PPAs were 94.6% (881/931) and 84.9% (790/931), respectively. For all negative samples, the negative percentage agreement values were >95%. Thus, most laboratories can reliably detect SARS-CoV-2. However, further improvement and optimization are required to ensure the accuracy of detection in panel members with lower concentrations of viral RNA.

Comparison of Nucleic Acid Extraction Methods for a Viral Metagenomics Analysis of Respiratory Viruses

Viral metagenomics next-generation sequencing (mNGS) is increasingly being used to characterize the human virome. The impact of viral nucleic extraction on virome profiling has been poorly studied. Here, we aimed to compare the sensitivity and sample and reagent contamination of three extraction methods used for viral mNGS: two automated platforms (eMAG; MagNA Pure 24, MP24) and the manual QIAamp Viral RNA Mini Kit (QIAamp). Clinical respiratory samples (positive for Respiratory Syncytial Virus or Herpes Simplex Virus), one mock sample (including five viruses isolated from respiratory samples), and a no-template control (NTC) were extracted and processed through an mNGS workflow. QIAamp yielded a lower proportion of viral reads for both clinical and mock samples. The sample cross-contamination was higher when using MP24, with up to 36.09% of the viral reads mapping to mock viruses in the NTC (vs. 1.53% and 1.45% for eMAG and QIAamp, respectively). The highest number of viral reads mapping to bacteriophages in the NTC was found with QIAamp, suggesting reagent contamination. Our results highlight the importance of the extraction method choice for accurate virome characterization.

Toscana, West Nile, Usutu and tick-borne encephalitis viruses: external quality assessment for molecular detection of emerging neurotropic viruses in Europe, 2017

BackgroundNeurotropic arboviruses are increasingly recognised as causative agents of neurological disease in Europe but underdiagnosis is still suspected. Capability for accurate diagnosis is a prerequisite for adequate clinical and public health response.AimTo improve diagnostic capability in EVD-LabNet laboratories, we organised an external quality assessment (EQA) focusing on molecular detection of Toscana (TOSV), Usutu (USUV), West Nile (WNV) and tick-borne encephalitis viruses (TBEV).MethodsSixty-nine laboratories were invited. The EQA panel included two WNV RNA-positive samples (lineages 1 and 2), two TOSV RNA-positive samples (lineages A and B), one TBEV RNA-positive sample (Western subtype), one USUV RNA-positive sample and four negative samples. The EQA focused on overall capability rather than sensitivity of the used techniques. Only detection of one, clinically relevant, concentration per virus species and lineage was assessed.ResultsThe final EQA analysis included 51 laboratories from 35 countries; 44 of these laboratories were from 28 of 31 countries in the European Union/European Economic Area (EU/EEA). USUV diagnostic capability was lowest (28 laboratories in 18 countries), WNV detection capacity was highest (48 laboratories in 32 countries). Twenty-five laboratories were able to test the whole EQA panel, of which only 11 provided completely correct results. The highest scores were observed for WNV and TOSV (92%), followed by TBEV (86%) and USUV (75%).ConclusionWe observed wide variety in extraction methods and RT-PCR tests, showing a profound absence of standardisation across European laboratories. Overall, the results were not satisfactory; capacity and capability need to be improved in 40 laboratories.

Automation of RNA-based biomarker extraction from dried blood spots for the detection of blood doping

Aim: Transcriptomic biomarkers originating from reticulocytes measured in dried blood spots (DBSs) may be reliable indicators of blood doping. Methods/results: Here, we examined changes in the expression levels of the erythropoiesis-related ALAS2, CA1 and SLC4A1 genes in DBS samples from elite athletes and volunteers of clinical study with recombinant erythropoietin dose. Conclusion: By comparing the mean intraday coefficients of variation for ALAS2L, ALASLC, CA1 and SLC4A1 between manual and automated RNA extractions, an average improvement was observed, whereas the assessment of interday variability provided comparable results for both manual and automated approaches. Our results confirmed that RNA biomarkers on DBS support are efficient to detect blood doping.

Kharat P, S. Saraf T, B. Somwanshi S, B. Shejul S, M. Jadhav K. Multifunctional nano-magnetic particles assisted viral RNA-extraction protocol for potential detection of COVID-19

The enduring outbreak of the corona virus disease (COVID-19) originated from China illustrates global concerns owing to their infective nature and time-consuming incubation. Even though diagnostic tools based on RT-PCR are being extensively employed at present, well-timed and precise diagnostics are still restricted because of the long-period and exhaustive man-power requirement. To tackle this problem, we herewith report the fabrication of the surface functionalised magnetic nanoparticles (MNP’s) and viral RNA-extraction protocol for potential detection of COVID-19. The zinc ferrite nanoparticles were prepared by combustion synthesis and its surface was functionalised by silica and carboxyl-modified polyvinyl alcohol. The MNP’s were characterized to confirm the nano-scale appearance and functionalization. The proposed model may provide the ability to extract the viral RNA from several specimens through automation process. In light of ease and proficiency, this protocol may significantly lessen the operation period and necessities for the present molecular-level diagnostic of COVID-19.

Development and validation of an RT-qPCR assay for rapid detection and quantification of hepatitis C virus RNA for routine testing in Moroccan clinical specimens

A one-step reverse transcription quantitative PCR (RT-qPCR) assay in combination with rapid RNA extraction was evaluated for routine testing of hepatitis C virus (HCV) RNA. Specific primers and probes were designed for the detection of a 150 bp sequence located in the 5'untranslated region (5'UTR) of HCV RNA. The target sequence was selected as the most conserved region between the six known HCV subtype sequences following an alignment. The assay was able to quantify a dynamic linear range of 10⁸ to 10¹ plasmid copies/reaction (r²  = 0.98) containing the target sequence. Two copies of this HCV plasmid corresponds to one international unit (IU) measured using a standard obtained by serial dilutions of the World Health Organization (WHO) standard. The detection limit of the assay was about 10 IU/mL of HCV RNA (20 copies/mL) in plasma samples. The assay was comparable to Cobas AmpliPrep/Cobas TaqMan® HCV Test, v2.0 Quantitative assay (Roche Molecular Systems, Inc., Branchburg, NJ) with correlation coefficient r²  = 0.98. The present assay could be completed within 3 hours from RNA extraction to data analysis of at least 30 plasma samples. Our test provides sufficient sensitivity, specificity, and reproducibility and proved to be fast, labor-saving, and cost-effective. Indeed, our system will definitely allow low-income countries to monitor accurately this viral infection and to efficiently treat their infected patients.

Comparison of oral Candida carriage in waterpipe smokers, cigarette smokers, and non-smokers

The aim of the present cohort study was to compare oral carriage of Candida in waterpipe smokers (WS), cigarette smokers (CS), and non-smokers (NS). A total of 141 individuals (46 WS, 45 CS, and 50 NS) were included. A questionnaire was used to gather demographic information and data on the daily frequency and duration of smoking habits, the reasons for smoking, and daily oral hygiene maintenance habits. Oral Candida (C.) samples were cultured and yeast species were identified using polymerase chain reaction. Unstimulated whole salivary flow rate (UWSFR) was also recorded. The numbers of missing teeth (MT) were counted and tongue lesions were clinically identified. C. albicans was the most prevalent yeast species isolated from all groups. Oral C. albicans carriage was higher among WS (P < 0.05) and CS (P < 0.05) than among NS. Oral C. tropicalis carriage, age, UWSFR and the number of MT were comparable among the groups. Oral Candida carriage was significantly higher among WS and CS than among NS. Therefore it appears that WS and CS are at an increased risk of developing oral candida infections.

Evaluation of a new extraction platform in combination with molecular assays useful for monitoring immunosuppressed patients

BACKGROUND

In the immunosuppressed, detection of viral reactivation at the earliest convenience and molecular monitoring are of paramount importance. Nucleic acid extraction has a major impact on the reliability of results obtained from molecular assays.

OBJECTIVES

The aim of this study was to investigate the accuracy of the new EMAG^® nucleic acid extraction platform and to compare the performance of the new platform to that of the standard NucliSENS^® easyMAG^® instrument in the routine clinical laboratory.

STUDY DESIGN

For accuracy testing, reference material and for comparison studies, clinical specimens were used. In addition, a lab-flow analysis including estimation of hands-on time and that for automated extraction was performed.

RESULTS

When accuracy was tested, all 89 results obtained were found to be concordant with the results expected. When 648 clinical results were compared, 85.7% were found to be within ±0.5 log₁₀ unit, 9.5% between ±0.5 and ±1.0 log₁₀ unit, and 4.8% more than ±1.0 log₁₀ unit. The overall time required for nucleic acid extraction of 8 samples in parallel was 94 min for the fully automated extraction mode and 82 min for the partly automated mode with the new platform, and 73 min with the standard instrument. Hands-on time was found to be shorter with the new platform.

CONCLUSIONS

The extraction performance of both platforms was found to be similar for EDTA whole blood, BAL, and urine specimens. The total turn-around time for nucleic acid extraction was found to be longer with the EMAG^® platform, whereas hands-on time was reduced.

Study on the anti-endotoxin effect of sinomenine using an Agilent genome array

BACKGROUND

Endotoxin is a significant contributing factor underlying the occurrence of fever, diarrhea, inflammation, edema, coagulation, shock and other syndromes associated with gram-negative bacterial infections. To date, there is no effective treatment for endotoxemia.

AIM

The aim of this study was to characterize differentially expressed genes in sinomenine-treated and lipopolysaccharide (LPS)-induced endothelial cells by microarray analysis and to determine the potential pharmacological activity of sinomenine.

DESIGN

The cultured cells of five treatment groups (n = 3) were collected. Participants: total RNA was extracted and subjected to Agilent Porcine 4 × 44 K whole genome microarray.

METHODS

Kyoto encyclopedia of genes and genomes and gene ontology software were applied to screen and analyze differentially regulated genes.

RESULTS

The results showed that 723 differentially regulated genes were identified including 410 up-regulated genes and 313 down-regulated genes in therapy group vs. LPS group. Ten genes may be key controlled genes in the pathogenesis of LPS, including five up-regulated genes (ARG1, TLR2, IL1A, VCAM1, DKK3) and five down-regulated genes (HABP2, ID1, CHDH, GPX3, PTGFR), which primarily contribute to biological processes such as inflammatory response, vascular lesion, metabolic process and cell cycle. IL1A and FMO3 were considered as potent target genes.

CONCLUSION

Global gene expression profile analysis showed that sinomenine might effectively be useful to regulate inflammatory responses as part of future anti-endotoxin therapies.

Nucleic Acid Extraction and Enrichment

Nucleic acid extraction is the first step of any amplification experiment no matter what kind of amplification is used to detect a specific pathogen. Efficient nucleic acid extraction is essential to obtain good results using any molecular test. The optimal extraction method should fulfill the following conditions: speed, short working time, cost-effectiveness, high sensitivity and specificity, good reproducibility, and safety. The methods can be divided into solution or column based according to differences of their principles. The automated extraction instruments have many advantages, and these have proven to be very useful. Moreover, in recent years, fully automated instruments combining NA extraction and amplification have been commercially available. However, the method itself does not provide assurance, and the DNA recovery can be different among various kits or instruments that use the similar principles. Therefore, it is important to carefully evaluate the performance of any extraction method used in the clinical microbiology laboratory even though manufacturers may have reported good validation results with specific organisms.

Persistence of Zika virus in conjunctival fluid of convalescence patients

A widespread epidemic of Zika fever, caused by Zika virus (ZIKAV) has spread throughout the Pacific islands, the Americas and Southeast Asia. The increased incidences of ocular anomalies observed in ZIKAV-infected infants and adults may be associated with the rapid spread of ZIKAV. The objective of this study was to check if ZIKAV could be detected in human tears after the first week of infection. Twenty-nine patients with PCR confirmed ZIKAV infection during the Singapore August 2016 ZIKAV outbreak were enrolled for the study. Detection and quantification of ZIKAV RNA was performed on conjunctival swabs collected from both eyes of these patients at the late convalescent phase (30 days post-illness). Efficiency of viral isolation from swab samples was confirmed by the limit of detection (as low as 0.1 PFU/µL, equivalent to copy number of 4.9) in spiked swabs with different concentrations of ZIKAV (PFU/µL). Samples from three patients were found positive by qRT-PCR for ZIKAV and the viral RNA copy numbers detected in conjunctival swabs ranged from 5.2 to 9.3 copies respectively. ZIKAV could persist in the tears of infected patients for up to 30 days post-illness, and may therefore possess a potential public health risk of transmission.

The Effect of Nucleic Acid Extraction Platforms and Sample Storage on the Integrity of Viral RNA for Use in Whole Genome Sequencing

Extraction of viral RNA and the storage of sample material are extremely important factors in the detection and whole genome sequencing (WGS) of viral pathogens. Although PCR-based detection methods focus on small amplicons, viral WGS applications require RNA of high quality and integrity for adequate sequence coverage and depth. This study examined the fitness of one manual and four automated RNA extraction platforms commonly used in diagnostic laboratories for use in metagenomic sequencing, how the practice of storing sample material in Qiagen buffer AVL before extraction affected the integrity of viral RNA and its suitability for use in amplicon-based WGS methods, and how the addition of Triton X-100 to buffer AVL affected the capability of the extraction platforms and the integrity of viral RNA in stored samples. This study found that the EZ1 platform gave the best performance of the automated platforms and gave comparable results to the frequently used manual Qiagen extraction protocol when extracted viral RNA was used in metagenomics sequencing. To maintain high levels of viral RNA integrity suitable for amplicon-based WGS, nucleic acid should be extracted from samples immediately, because even short storage periods in buffer AVL have a severe effect on integrity, and the addition of Triton X-100 had little effect on the quality of viral material for WGS.

A sensitive one-step TaqMan amplification approach for detection of rubella virus clade I and II genotypes in clinical samples

Although teratogenic rubella virus (RV) causes a vaccine-preventable disease, it is still endemic in several countries worldwide. Thus, there is a constant risk of RV importation into non-endemic areas. RV monitoring, especially during measles and Zika virus outbreaks, requires reliable diagnostic tools. For this study, a TaqMan-based one-step reverse transcription-quantitative PCR (RT-qPCR) assay, with the p90 gene as a novel and so far unexplored target for detection of clade I and II genotypes, was developed and evaluated. Automated nucleic acid extraction was carried out. Performance characteristics of the TaqMan RT-qPCR assay were determined for a RV plasmid standard and RNA extracted from virus-infected cell culture supernatants representing clade I and II genotypes. Diagnostic specificity and sensitivity were validated against other RNA and DNA viruses, relevant for RV diagnostic approaches and for RV-positive clinical samples, respectively. The assay is specific and highly sensitive with a limit of detection as low as five to one copies per reaction or 200 infectious virus particles per ml. The coefficients of variation (CV) were specified as intra- (within one run) and inter- (between different runs) assay variation, and calculated based on the standard deviations for the obtained Ct values of the respective samples. Intra- and inter-assay CV values were low, with a maximum of 3.4% and 2.4%, respectively. The assay was shown to be suitable and specific for the analysis of clinical samples. With p90 as a novel target, the highly sensitive and specific TaqMan assay outlined in this study is suitable for RV diagnosis worldwide.

Comparison of four commercial DNA extraction kits for the recovery of Bacillus spp. spore DNA from spiked powder samples

Bacillus spp. include human pathogens such as Bacillus anthracis, the causative agent of anthrax and a biothreat agent. Bacillus spp. form spores that are physically highly resistant and may remain active over sample handling. We tested four commercial DNA extraction kits (QIAamp DNA Mini Kit, RTP Pathogen Kit, ZR Fungal/Bacterial DNA MiniPrep, and genesig Easy DNA/RNA Extraction kit) for sample inactivation and DNA recovery from two powders (icing sugar and potato flour) spiked with Bacillus thuringiensis spores. The DNA was analysed using a B. thuringiensis-specific real-time PCR assay. The detection limit was 3×10(1)CFU of spiked B. thuringiensis spores with the QIAamp DNA Mini, RTP Pathogen, and genesig Easy DNA/RNA Extraction kits, and 3×10(3)CFU with the ZR Fungal/Bacterial DNA MiniPrep kit. The results showed that manual extraction kits are effective and safe for fast and easy DNA extraction from powder samples even in field conditions. Adding a DNA filtration step to the extraction protocol ensures the removal of Bacillus spp. spores from DNA samples without affecting sensitivity.

16S rRNA gene sequencing is a non-culture method of defining the specific bacterial etiology of ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is an acquired respiratory tract infection following tracheal intubation. The most common hospital-acquired infection among patients with acute respiratory failure, VAP is associated with a mortality rate of 20-30%. The standard bacterial culture method for identifying the etiology of VAP is not specific, timely, or accurate in identifying the bacterial pathogens. This study used 16S rRNA gene metagenomic sequencing to identify and quantify the pathogenic bacteria in lower respiratory tract and oropharyngeal samples of 55 VAP patients. Sequencing of the 16S rRNA gene has served as a valuable tool in bacterial identification, particularly when other biochemical, molecular, or phenotypic identification techniques fail. In this study, 16S rRNA gene sequencing was performed in parallel with the standard bacterial culture method to identify and quantify bacteria present in the collected patient samples. Sequence analysis showed the colonization of multidrug-resistant strains in VAP secretions. Further, this method identified Prevotella, Proteus, Aquabacter, and Sphingomonas bacterial genera that were not detected by the standard bacterial culture method. Seven categories of bacteria, Streptococcus, Neisseria, Corynebacterium, Acinetobacter, Staphylococcus, Pseudomonas and Klebsiella, were detectable by both 16S rRNA gene sequencing and standard bacterial culture methods. Further, 16S rRNA gene sequencing had a significantly higher sensitivity in detecting Streptococcus and Pseudomonas when compared to standard bacterial culture. Together, these data present 16S rRNA gene sequencing as a novel VAP diagnosis tool that will further enable pathogen-specific treatment of VAP.

A review of traditional and contemporary assays for direct and indirect detection of Equid herpesvirus 1 in clinical samples

Equid herpesvirus 1 (EHV-1) is one of the most economically important equine viral pathogens. Its clinical manifestations in horses vary from acute upper respiratory tract disease, abortion, or neonatal death, to neurological disease termed equine herpesviral myeloencephalopathy, which may lead to paralysis and a fatal outcome. Successful identification of EHV-1 infection in horses depends on a variety of factors such as suitable case selection with emphasis on timing of sample collection, selection of appropriate sample(s) based on the clinical manifestations, application of relevant diagnostic technique(s) and/or test(s), and careful evaluation and interpretation of laboratory results. Several traditional serologic and virus isolation assays have been described; however, these assays have inherent limitations that prevent rapid and reliable detection of EHV-1. The advent of molecular biologic techniques has revolutionized the diagnosis of infectious diseases in humans and animal species. Specifically, polymerase chain reaction (PCR)-based assays have allowed detection of nucleic acid in clinical specimens precisely and rapidly as compared to the traditional methods that detect the agent or antigen, or agent-specific antibodies in serum. The new molecular methods, especially real-time PCR, can be a very useful means of EHV-1 detection and identification. Veterinarians involved in equine practice must be aware of the advantages and disadvantages of various real-time PCR assays, interpretation of viral genetic marker(s), and latency in order to provide the best standard of care for their equine patients.

Comparison of three magnetic bead surface functionalities for RNA extraction and detection

Magnetic beads are convenient for extracting nucleic acid biomarkers from biological samples prior to molecular detection. These beads are available with a variety of surface functionalities designed to capture particular subsets of RNA. We hypothesized that bead surface functionality affects binding kinetics, processing simplicity, and compatibility with molecular detection strategies. In this report, three magnetic bead surface chemistries designed to bind nucleic acids, silica, oligo (dT), and a specific oligonucleotide sequence were evaluated. Commercially available silica-coated and oligo (dT) beads, as well as beads functionalized with oligonucleotides complementary to respiratory syncytial virus (RSV) nucleocapsid gene, respectively recovered ∼75, ∼71, and ∼7% target RSV mRNA after a 1 min of incubation time in a surrogate patient sample spiked with the target. RSV-specific beads required much longer incubation times to recover amounts of the target comparable to the other beads (∼77% at 180 min). As expected, silica-coated beads extracted total RNA, oligo (dT) beads selectively extracted total mRNA, and RSV-specific beads selectively extracted RSV N gene mRNA. The choice of bead functionality is generally dependent on the target detection strategy. The silica-coated beads are most suitable for applications that require nucleic acids other than mRNA, especially with detection strategies that are tolerant of a high concentration of nontarget background nucleic acids, such as RT-PCR. On the other hand, oligo (dT) beads are best-suited for mRNA targets, as they bind biomarkers rapidly, have relatively high recovery, and enable detection strategies to be performed directly on the bead surface. Sequence-specific beads may be best for applications that are not tolerant of a high concentration of nontarget nucleic acids that require short RNA sequences without poly(A) tails, such as microRNAs, or that perform RNA detection directly on the bead surface.

RNA extraction from equine samples for equine influenza virus

The primary goals of this chapter are to discuss common viral RNA isolation and purification methods that are routinely used by various diagnostic laboratories, to highlight the advantages and drawbacks of each method, and to identify the most suitable and reliable method to increase the sensitivity and specificity of RT-PCR assays for the detection of equine influenza virus (EIV) in clinical specimens. Our experiences and review of literature show that magnetic bead-based nucleic extraction methods (manual and automatic) work well for isolation and purification of EIV RNA from nasal swab specimens. Furthermore, most of the information presented in this chapter could be directly applicable to isolation and purification of nucleic acids (both DNA and RNA) from other equine clinical samples.

Expression profiles uncover the relationship between erythropoietin and cell proliferation in rat hepatocytes after a partial hepatectomy

Erythropoietin (EPO) has a beneficial effect on hepatic cell proliferation during liver regeneration. However, the underlying mechanism has not yet been elucidated. To uncover the proliferation response of EPO in rat liver regeneration after partial hepatectomy (PH) at the cellular level, hepatocytes (HCs) were isolated using Percoll density gradient centrifugation. The genes of the EPO-mediated signaling pathway and the target genes of the transcription factor (TF) in the pathway were identified in a pathway and TF database search. Their expression profiles were then detected using Rat Genome 230 2.0 Microarray. The results indicated that the EPO-mediated signaling pathway is involved in 19 paths and that 124 genes participate, of which 32 showed significant changes and could be identified as liver regeneration-related genes. In addition, 443 targets regulated by the TFs of the pathway and 60 genes associated with cell proliferation were contained in the array. Subsequently, the synergetic effect of these genes in liver regeneration was analyzed using the E(t) mathematical model based on their expression profiles. The results demonstrated that the E(t) values of paths 3, 8, 12 and 14-17 were significantly strengthened in the progressing phase of liver regeneration through the RAS/MEK/ERK or PI3K/AκT pathways. The synergetic effect of the target genes, in parallel with target-related cell proliferation, was also enhanced 12-72 h after PH, suggesting a potential positive effect of EPO on HC proliferation during rat liver regeneration. These data imply that the EPO receptor may allow EPO to promote HC proliferation through paths 3, 8, 12 and 14-17, mediating the RAS/MEK/ERK and PI3K/AκT pathways in rat liver regeneration after PH.

Association between glycemic status and oral Candida carriage in patients with prediabetes

OBJECTIVE

This study assessed the association between glycemic status and oral Candida carriage among patients with prediabetes.

STUDY DESIGN

This was a comparative study of oral Candida carriage among individuals with prediabetes. Oral yeast samples were collected from 150 individuals: group A was 43 patients with prediabetes (fasting blood glucose levels and hemoglobin A1c, 100 to 125 mg/dL and ≥5%, respectively); group B was 37 individuals previously considered prediabetic but having fasting blood glucose levels <100 mg/dL and hemoglobin A1c <5%; and group C was 70 medically healthy individuals. Oral yeasts were identified using standard techniques. Unstimulated whole salivary flow rate and number of missing teeth were recorded.

RESULTS

Oral Candida was isolated from 100% of patients with prediabetes and from 65.7% of control participants. Candida albicans carriage was higher among patients with prediabetes (48.7%) (P < .01) and patients in group A (51.2%) (P < .01) than among controls (25.7%). Candida carriage, unstimulated whole salivary flow rate, and number of missing teeth were similar in groups A and B.

CONCLUSIONS

Oral Candida carriage was higher in patients with prediabetes than in controls and was independent of glycemic status in patients with prediabetes.

Gene profile in the spleen under massive partial hepatectomy using complementary DNA microarray and pathway analysis

BACKGROUND AND AIM

In general, the spleen is one of the abdominal organs connected by the portal system, and a splenectomy improves hepatic functions in the settings of partial hepatectomy (Hx) for portal hypertensive cases or living donor liver transplantation with excessive portal vein flow. Those precise mechanisms remain still unclear; therefore, we investigated the DNA expression profile in the spleen after 90% Hx in rats using complementary DNA microarray and pathway analysis.

METHODS

Messenger RNAs (mRNAs) were prepared from three rat spleens at each time point (0, 3, and 6 h after 90% Hx). Using the gene chip, mRNA was hybridized to Affymetrix GeneChip Rat Genome 230 2.0 Array (Affymetrix®) and pathway analysis was done with Ingenuity Pathway Analysis (IPA®).

RESULTS

We determined the 3-h or 6-h/0-h ratio to assess the influence of Hx, and cut-off values were set at more than 2.0-fold or less than 1/2 (0.5)-fold. Chemokine activity-related genes including Cxcl1 (GRO1) and Cxcl2 (MIP-2) related pathway were upregulated in the spleen. Also, immediate early response genes including early growth response-1 (EGR1), FBJ murine osteosarcoma (FOS) and activating transcription factor 3 (ATF3) related pathway were upregulated in the spleen.

CONCLUSIONS

We concluded that in the spleen the expression of numerous inflammatory-related genes would occur after 90% Hx. The spleen could take a harmful role and provide a negative impact during post Hx phase due to the induction of chemokine and transcription factors including GRO1 and EGR1.

An integrated lab-on-chip for rapid identification and simultaneous differentiation of tropical pathogens

Tropical pathogens often cause febrile illnesses in humans and are responsible for considerable morbidity and mortality. The similarities in clinical symptoms provoked by these pathogens make diagnosis difficult. Thus, early, rapid and accurate diagnosis will be crucial in patient management and in the control of these diseases. In this study, a microfluidic lab-on-chip integrating multiplex molecular amplification and DNA microarray hybridization was developed for simultaneous detection and species differentiation of 26 globally important tropical pathogens. The analytical performance of the lab-on-chip for each pathogen ranged from 10² to 10³ DNA or RNA copies. Assay performance was further verified with human whole blood spiked with Plasmodium falciparum and Chikungunya virus that yielded a range of detection from 200 to 4×10⁵ parasites, and from 250 to 4×10⁷ PFU respectively. This lab-on-chip was subsequently assessed and evaluated using 170 retrospective patient specimens in Singapore and Thailand. The lab-on-chip had a detection sensitivity of 83.1% and a specificity of 100% for P. falciparum; a sensitivity of 91.3% and a specificity of 99.3% for P. vivax; a positive 90.0% agreement and a specificity of 100% for Chikungunya virus; and a positive 85.0% agreement and a specificity of 100% for Dengue virus serotype 3 with reference methods conducted on the samples. Results suggested the practicality of an amplification microarray-based approach in a field setting for high-throughput detection and identification of tropical pathogens.

Tropical diseases consist of a group of debilitating and fatal infections that occur primarily in rural and urban settings of tropical and subtropical countries. While the primary indices of an infection are mostly the presentation of clinical signs and symptoms, outcomes due to an infection with tropical pathogens are often unspecific. Accurate diagnosis is crucial for timely intervention, appropriate and adequate treatments, and patient management to prevent development of sequelae and transmission. Although, multiplex assays are available for the simultaneous detection of tropical pathogens, they are generally of low throughput. Performing parallel assays to cover the detection for a comprehensive scope of tropical infections that include protozoan, bacterial and viral infections is undoubtedly labor-intensive and time consuming. We present an integrated lab-on-chip using microfluidics technology coupled with reverse transcription (RT), PCR amplification, and microarray hybridization for the simultaneous identification and differentiation of 26 tropical pathogens that cause 14 globally important tropical diseases. Such diagnostics capacity would facilitate evidence-based management of patients, improve the specificity of treatment and, in some cases, even allow contact tracing and other disease-control measures.

Effects of splenectomy on hepatic gene expression profiles after massive hepatectomy in rats

BACKGROUND AND AIM

Possible spleno-hepatic relationships affected by hepatectomy still remained unclear. We have previously reported that splenectomy may ameliorate liver injuries and promote appropriate liver regeneration after massive hepatectomy. Therefore, we investigated the effects of splenectomy on the DNA expression profile in the liver after massive hepatectomy in rats.

METHODS

Rats were divided into the following two groups: 90% hepatectomy (Hx group) and 90% hepatectomy with splenectomy (Hx + Sp group). Rats were sacrificed 3 and 6 h after surgery, and mRNA from liver tissue was isolated and hybridized to Affymetrix GeneChip Rat Genome 230 2.0 Array (Affymetrix, Santa Clara, CA, USA) and a pathway analysis was done with Ingenuity Pathway Analysis (Ingenuity Systems, Mountain View, CA, USA).

RESULTS

We determined the Hx + Sp/Hx ratio to assess the influence of splenectomy, and cut-off values were set at more than 2.0-fold or less than 1/2 (0.5)-fold. Immediate early response gene including early growth response-1 and FBJ murine osteosarcoma-related pathways were markedly downregulated by splenectomy. In contrast, heme oxygenase-1 gene-related pathway was upregulated by splenectomy.

CONCLUSIONS

Splenectomy provided the protective effects for liver failure and promoted liver regeneration, possibly owing to the downregulation of immediate early response genes and upregulation of the heat shock protein, heme oxygenase-1.

Nucleic Acid Extraction Techniques

Since thermostable Taq DNA polymerase was discovered in 1987, nucleic acid amplification techniques have made great strides and contributed greatly to progress in the life sciences. These techniques were introduced into the clinical laboratory and have produced great changes in diagnostic tools and tests. In particular, there have been many innovative molecular testing developments in the field of diagnostic microbiology.

Oral Candida carriage and species prevalence amongst habitual gutka-chewers and non-chewers

Oral Candida colonisation is higher in tobacco smokers as compared to non-smokers; however, it remains unknown whether smokeless tobacco chewers are susceptible to increased oral Candida colonisation. The aim was to determine the oral Candida carriage and species prevalence amongst habitual gutka-chewers and non-chewers in a cohort from Karachi, Pakistan. Forty-five gutka-chewers and 45 non-chewers were included. Information regarding age, sex, duration of gutka-chewing habit, daily frequency of gutka consumption, duration of holding gutka in the mouth, daily frequency of tooth-brushing and tongue brushing was collected using a questionnaire. Oral yeast samples were collected by scraping the dorsum of the tongue and bilateral buccal mucosa with a sterile cotton swab. Identification of yeast species was performed using standard techniques. Tongue lesions were identified and recorded. Unstimulated whole salivary flow rate (UWSFR) was also measured. There was no significant difference in the mean age, UWSFR and oral Candida carriage among gutka-chewers and non-chewers. Individuals were chewing gutka since 4·4 years and were consuming five gutka sachets daily. Candida albicans (C. albicans) was the most common yeast species isolated from 57·8% gutka-chewers and 64.4% non-chewers. In 24.4% gutka-chewers and 22·2% non-chewers, two candidal strains (C. albicans and Candida tropicalis) were isolated. In conclusion, the present results indicated no significant difference in oral Candida carriage in habitual gutka-chewers and non-chewers.

Evaluation of four different systems for extraction of RNA from stool suspensions using MS-2 coliphage as an exogenous control for RT-PCR inhibition

Knowing when, and to what extent co-extracted inhibitors interfere with molecular RNA diagnostic assays is of utmost importance. The QIAamp Viral RNA Mini Kit (A); MagNA Pure LC2.0 Automatic extractor (B); KingFisher (C); and NucliSENS EasyMag (D) RNA extraction systems were evaluated for extraction efficiency and co-purification of inhibitors from stool suspensions. Real-Time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR) of MS-2 coliphage spiked into each system's lysis buffer served as an external control for both. Cycle thresholds (Cts) of the MS2 were determined for RNA extracted from stool suspensions containing unknown (n = 93) or varying amounts of inhibitors (n = 92). Stool suspensions from the latter group were also used to determine whether MS-2 and enterovirus rRT-PCR inhibitions were correlated. Specifically 23 RNA extracts from stool suspensions were spiked with enterovirus RNA after extraction and 13 of these stool suspension were spiked with intact enterovirus before extraction. MS2 rRT-PCR inhibition varied for RNAs extracted by the different systems. Inhibition was noted in 12 (13.0%), 26 (28.3%), 7 (7.6%), and 7 (7.6%) of the first 93 RNA extracts, and 58 (63.0%), 55 (59.8%), 37 (40.2%) and 30 (32.6%) of the second 92 extracts for A, B, C, and D, respectively. Furthermore, enterovirus rRT-PCR inhibition correlated with MS2 rRT-PCR inhibition for added enterovirus RNA or virus particles. In conclusion, rRT-PCR for MS-2 RNA is a good predictor of inhibition of enterovirus RNA extracted from stool suspensions. EasyMag performed the best, however all four extraction methods were suitable provided that external controls identified problematic samples.

Genotype 3 diversity and quantification of hepatitis E virus RNA

Genotype 3 hepatitis E viruses (HEVs) are distributed across the world and are now considered to be an emerging public health concern in industrialized countries. At least 10 genotype 3 subtypes have been identified in humans and animals worldwide. It was recently reported that the sensitivities of HEV RNA assays differ greatly. We have assessed the influence of genotype 3 diversity on the performances of two HEV RNA assays: one targeting the ORF3 gene and the other targeting the ORF2 gene. We tested a panel of 5 HEV-positive reference samples of genotypes 3a, 3b, 3c, 3e, and 3f at 10-fold serial dilutions. The HEV RNA concentrations obtained with both reverse transcription (RT)-PCRs were correlated, but the RT-PCR based on ORF2 underestimated the HEV RNA concentrations. The mean [ORF3 - ORF2] difference was 1.41 log copies/ml. We also tested 34 clinical specimens of genotypes 3c (n = 15), 3e (n = 4), and 3f (n = 15), representing the most prevalent subtypes in Europe. The mean [ORF3 - ORF2] differences were 1.41 log copies/ml for genotype 3c, 0.96 log copies/ml for genotype 3e, and 0.70 log copies/ml for genotype 3f. The bias between the 2 RT-PCR assays was significantly greater for genotype 3c than for genotype 3f (P = 0.007). We therefore recommend the use of an RT-PCR protocol based on ORF3 to quantify HEV RNA of genotype 3 strains.