qPCR Primers Research Articles

In Vivo Validation of Alternative FDXR Transcripts in Human Blood in Response to Ionizing Radiation.

Following cell stress such as ionising radiation (IR) exposure, multiple cellular pathways are activated. We recently demonstrated that ferredoxin reductase (FDXR) has a remarkable IR-induced transcriptional responsiveness in blood. Here, we provided a first comprehensive FDXR variant profile following DNA damage. First, specific quantitative real-time polymerase chain reaction (qPCR) primers were designed to establish dose-responses for eight curated FDXR variants, all up-regulated after IR in a dose-dependent manner. The potential role of gender on the expression of these variants was tested, and neither the variants response to IR nor the background level of expression was profoundly affected; moreover, in vitro induction of inflammation temporarily counteracted IR response early after exposure. Importantly, transcriptional up-regulation of these variants was further confirmed in vivo in blood of radiotherapy patients. Full-length nanopore sequencing was performed to identify other FDXR variants and revealed the high responsiveness of FDXR-201 and FDXR-208. Moreover, FDXR-218 and FDXR-219 showed no detectable endogenous expression, but a clear detection after IR. Overall, we characterised 14 FDXR transcript variants and identified for the first time their response to DNA damage in vivo. Future studies are required to unravel the function of these splicing variants, but they already represent a new class of radiation exposure biomarkers.

Combined Use of Diagnostic Fumarate Addition Metabolites and Genes Provides Evidence for Anaerobic Hydrocarbon Biodegradation in Contaminated Groundwater.

The widespread use of hydrocarbon-based fuels has led to the contamination of many natural environments due to accidental spills or leaks. While anaerobic microorganisms indigenous to many fuel-contaminated groundwater sites can play a role in site remediation (e.g., monitored natural attenuation, MNA) via hydrocarbon biodegradation, multiple lines of evidence in support of such bioremediation are required. In this study, we investigated two fuel-contaminated groundwater sites for their potential to be managed by MNA. Microbial community composition, biogeochemical indicators, fumarate addition metabolites, and genes diagnostic of both alkane and alkyl-monoaromatic hydrocarbon activation were assessed. Fumarate addition metabolites and catabolic genes were detected for both classes of hydrocarbon biodegradation at both sites, providing strong evidence for in situ anaerobic hydrocarbon biodegradation. However, relevant metabolites and genes did not consistently co-occur within all groundwater samples. Using newly designed mixtures of quantitative polymerase chain reaction (qPCR) primers to target diverse assA and bssA genes, we measured assA gene abundances ranging from 105–108 copies/L, and bssA gene abundances ranging from 105–1010 copies/L at the sites. Overall, this study demonstrates the value of investigating fuel-contaminated sites using both metabolites and genes diagnostic of anaerobic hydrocarbon biodegradation for different classes of hydrocarbons to help assess field sites for management by MNA.

BrassicaEDB: A Gene Expression Database for Brassica Crops.

The genus Brassica contains several economically important crops, including rapeseed (Brassica napus, 2n = 38, AACC), the second largest source of seed oil and protein meal worldwide. However, research in rapeseed is hampered because it is complicated and time-consuming for researchers to access different types of expression data. We therefore developed the Brassica Expression Database (BrassicaEDB) for the research community. In the current BrassicaEDB, we only focused on the transcriptome level in rapeseed. We conducted RNA sequencing (RNA-Seq) of 103 tissues from rapeseed cultivar ZhongShuang11 (ZS11) at seven developmental stages (seed germination, seedling, bolting, initial flowering, full-bloom, podding, and maturation). We determined the expression patterns of 101,040 genes via FPKM analysis and displayed the results using the eFP browser. We also analyzed transcriptome data for rapeseed from 70 BioProjects in the SRA database and obtained three types of expression level data (FPKM, TPM, and read counts). We used this information to develop the BrassicaEDB, including “eFP”, “Treatment”, “Coexpression”, and “SRA Project” modules based on gene expression profiles and “Gene Feature”, “qPCR Primer”, and “BLAST” modules based on gene sequences. The BrassicaEDB provides comprehensive gene expression profile information and a user-friendly visualization interface for rapeseed researchers. Using this database, researchers can quickly retrieve the expression level data for target genes in different tissues and in response to different treatments to elucidate gene functions and explore the biology of rapeseed at the transcriptome level.

Quantitative PCR assay for the simultaneous identification and enumeration of multiple Karenia species.

Quantitative PCR (qPCR) is the method of choice for specific detection and quantification of harmful algal bloom (HAB) species. Development of qPCR assay for simultaneous enumeration of species that frequently co-exist in HABs is required. A high sensitivity TaqMan qPCR assay, using probe and primers, located at ITS1-5.8S-ITS2 rDNA region, detecting, specifically, Karenia selliformis, K. bidigitata, and K. mikimotoi, was designed. ITS1-5.8S-ITS2 rDNA region copy numbers per Karenia cell genome were estimated to 217.697 ± 67.904, allowing cell quantification. An application of the designed methodology in field samples has been conducted, and it showed high sensitivity (detection of around 10-1 cell/100 mg of bivalve mollusk tissue, equivalent to about 20 copies of the target sequence). We suggest that the optimized method could contribute to early detection of three closely related Karenia species in seafood cultivating areas to promote control quality, guarantee a fast and effective intervention, and improve public health prevention.

Identification of Spruce Budworm Natural Enemies Using a qPCR-Based Molecular Sorting Approach

Annual monitoring of mortality agents in the course of a spruce budworm (Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae)) population cycle is essential to understanding the factors governing the rise and collapse of outbreaks. To date, assessments of causes of budworm mortality have relied on laboratory rearing of field-collected larvae, followed by visual identification of emerging parasitoids and/or microscopic analysis of pathogens in larval carcasses. Although this approach has provided vital information on the abundance and identity of mortality agents, the procedure is labor-intensive and has limits in terms of accuracy. To overcome these shortcomings, we developed a molecular identification tool that makes use of real-time quantitative PCR (qPCR) and TaqMan® technologies. The tool relies on taxon-specific molecular variants (single nucleotide polymorphism [SNP] markers) found in mitochondrial (COI) and nuclear (28S rDNA) genes, for parasitoids, and in the nuclear SSU rDNA gene for microsporidian pathogens; these are then used as molecular signatures targeted by qPCR primers and TaqMan probes. Thus, the design of several sets of primers and probes deployed in multiplex format enables the identification of natural enemies via a molecular sorting process, bypassing barcode sequencing. Crude budworm DNA extracts are processed through a first module that detects dipteran and hymenopteran parasitoids, and microsporidian infections. Positive samples are then processed for species determination using three additional modules, enabling the identification of 20 common natural enemies of the spruce budworm. The tool has been fully validated using DNA samples from all comprised taxa, and both its sensitivity and accuracy compared favorably with the rearing-based method in an analysis of field-collected budworms. Using this tool, sample processing can be completed within two days, does not require larval rearing, provides accurate species identification, and can be conducted by technical staff without extensive molecular biology or insect taxonomy training.

60 specific eDNA qPCR assays to detect invasive, threatened, and exploited freshwater vertebrates and invertebrates in Eastern Canada

AbstractPractical applications of environmental DNA (eDNA) are in exponential expansion, especially for the assessment and monitoring of freshwater metazoans. Because eDNA sampling and analysis is noninvasive, it improves the detection of threatened, invasive, and exploited species for which monitoring may be challenging. Species detection efforts using a combination of eDNA and qPCR have been highly successful and, as a result, their use in species monitoring is expanding rapidly. We developed qPCR primers and probes in order to monitor many invasive, threatened, or exploited aquatic species as part of various monitoring eDNA projects in the province of Québec, Canada. Here, we present a total of 60 species‐specific qPCR assays (including PCR protocols, primers, and TaqMan probes sequences) developed for the detection of 45 fishes, six amphibians, five reptiles, two mollusks, and two crustaceans. These comprised nine and 27 species, respectively, listed as invasive and threatened in Eastern Canada. These resources should be of broad usefulness not only for monitoring studies based in Québec but throughout the geographic range of the targeted species in North America.

A sensitive and specific SYBR Green-based qPCR assay for detecting scale drop disease virus (SDDV) in Asian sea bass.

Scale drop disease virus (SDDV) is a megalocytivirus known to cause disease in Asian sea bass in Southeast Asia. To support SDDV diagnosis and surveillance, we report on a sensitive and specific SYBR Green qPCR assay. The qPCR primers were designed to target a 135 bp fragment of the SDDV ATPase gene. The optimized SDDV qPCR assay reliably detected 2 copies of a plasmid dsDNA control and did not cross-amplify DNA to any of 12 viral or bacterial pathogens commonly found in aquatic animals. When assessed with 86 field samples, the assay detected SDDV in DNA extracted from each of 34 scale drop disease-affected fish collected from 5 affected farms. The qPCR also detected SDDV in DNA from 30 of 52 overtly healthy fish collected from 9 farms where SDDV had not been detected previously, using a semi-nested conventional PCR. The higher sensitivity of our SDDV qPCR assay can thus be useful in detecting fish with subclinical/chronic infections. However, the qPCR showed that SDDV DNA loads varied from 8.0 × 102 to 6.8 × 104 viral DNA copies per 200 ng DNA template among the 8 organ tissue types sampled from 3 diseased fish. In circumstances requiring SDDV to be detected unequivocally in subclinical carriers with lower-level infection, qPCR testing of more than one type of tissue is advisable.

Quantification of Neurospora crassa mitochondrial DNA using quantitative real-time PCR.

The filamentous fungus Neurospora crassa is a popular model organism used in a wide range of biochemical and genetic studies and vastly used in mitochondrial research. Despite the relevance of mitochondria in N. crassa biology, no method for quantification of mitochondrial DNA (mtDNA) is currently available. Quantitative real-time PCR (qPCR) is a powerful tool, with a wide range of applications, and has been used for the quantification of nucleic acids in humans and a few other species. Here we present a new qPCR assay for relative quantification of N. crassa mtDNA. Three sets of qPCR primers targeting different regions of the mitochondrial genome were tested for mtDNA quantification. The qPCR was successfully validated in N. crassa strains from different geographical locations, representing the vast genetic diversity of this species, and knockout mutant strains. Moreover the assay proved to be efficient in templates with varied amounts of mitochondria, obtained through different DNA extraction methods. The qPCR performed well in all tested samples revealing a higher amount of mtDNA than nuclear DNA in all cases. This technique will facilitate the characterization of mtDNA of N. crassa in future studies and can be used as a tool to validate methods of mitochondria isolation. SIGNIFICANCE AND IMPACT OF THE STUDY: The standardization of quantitative real-time PCR (qPCR) techniques is essential to enable and facilitate future comparisons. Neurospora crassa is a model organism with a lot of potential in different fields of study. Here we use N. crassa to develop and establish an assay to quantify mitochondrial DNA using qPCR. We tested strains with different geographical background and our data demonstrated the usefulness of this assay to quantify mitochondrial DNA in N. crassa. This technique can be useful in a wide variety of applications and in different types of studies.

Quantitative polymerase chain reaction offers improved diagnostic and analytical sensitivity in identifying differential microsporidium (Loma morhua) infections among family lines of cultured Atlantic cod (Gadus morhua)

The failed attempt to establish Atlantic cod as an alternate aquaculture species in eastern Canada is due in part to hatchery outbreaks of the microsporidium Loma morhua during selective breeding programs. The sporadic nature of microsporidian epizootics during fish culture emphasizes the need for streamlined quantitative diagnostic approaches that help promote development of disease mitigation strategies. The current gold standard for assessing infection status relies on proficiency with parasitological confirmation of hypertrophied host cells (xenomas) that house infectious microsporidian spores. Parasite quantification is complicated with certain host organs showing better diagnostic utility, xenomas being heterogeneously distributed throughout these tissues, variable numbers of spores occurring within xenomas, and with pre-xenoma life-stages being difficult to identify using gold standard procedures. Herein, individuals from ten cod families with differential susceptibility to L. morhua were analyzed using a quantitative PCR (qPCR) assay, developed in accordance to the Minimum Information Required for Quantitative Experiments (MIQE) guidelines, to assess assay utility in quantifying infections relative to the gold standard procedure. Heterogeneous parasite distribution within spleens necessitated development of a tissue disruption protocol (FastPrep homogenizer; MP Biomedical) yielding a homogenous preparation for standardized DNA extractions. qPCR primers and a hydrolysis probe targeting a region of large subunit ribosomal DNA (rDNA) enable L. morhua to be distinguished from congeneric species infecting non-gadid hosts, but not those infecting gadid hosts. Parasite rDNA copies were normalized to Atlantic cod glyceraldehyde-3-phosphate dehydrogenase genomic DNA and to spleen weight. The qPCR assay demonstrates linearity (R2 = 0.971 to 0.999; range) throughout a large range of five log10 plasmid concentrations (102 to 106 titrated in host DNA), low variability (CV = 11.2–23.2%; n = 11 separate reactions), and the lower limit of detection is 10 plasmid copies. Quantification of parasite rDNA among ten cod families with differential infections resulted in a positive correlation with gold standard xenoma enumeration/confirmation (Pearson Correlation, r = 0.71), thereby validating effectiveness of qPCR in the absence of parasitological expertise. Furthermore, three fish lacking morphologically discernible spleen xenomas were identified as false negatives based on qPCR detection of 141–242 rDNA copies per 200 ng of spleen DNA, thereby confirming infection. This finding extends qPCR assay utility to detection of even subclinical infections. This qPCR assay improves diagnostic and analytical sensitivity in detecting L. morhua infections, facilitates empirical assessment of preventative/therapeutic treatment of microsporidian infections, and supports studies to identify biomarkers that promote selection of broodstock fishes that resist microsporidian disease.

Nanoarchitectured structure and population dynamics of anaerobic ammonium oxidizing (anammox) bacteria in a wastewater treatment plant

Studies on microbial community and population dynamics are essential for the successful development, monitoring and operation of biological wastewater treatment systems. Especially for novel or sustainable systems such as the anaerobic ammonium oxidizing (anammox) process that are not yet well explored. Here we collected granular microbial sludge samples and investigated a community of anammox bacteria over a period of four years, divided into eight stages in a full scale simultaneous partial nitrification, anammox and denitrification (SNAD) process for treating landfill leachate. Specific qPCR primers were designed to target and quantify the two most abundant anammox species, Candidatus Kuenenia stuttgartiensis (KS) and Candidatus Brocadia anammoxidans (BA). The two species were monitored and could explain the dynamic shift of the anammox community corresponding to the operating conditions. Using the newly designed KS-specific primer (KSqF3/KSqR3) and BA-specific primer (BAqF/BAqR), we estimated the amounts of KS and BA to be in the range of 6.2 × 106 to 5.9 × 108 and 1.1 × 105 to 4.1 × 107 copies μg−1 DNA, respectively. KS was found to be the dominant species in all anammox granules studied and played an important role in the formation of granules. The KS/BA ratio was positively correlated to the size of granules in the reactor and ammonia nitrogen removal efficiency of the treatment plant.

Expression pattern of heat shock protein genes in sheep

Objective: To recognize the expression patterns of HSP 70 and HSP 90 genes of two local sheep breeds. Design: Descriptive study Animals: Fifty ewes (25 Barki and 25 Abu Dlik). Procedures: This investigation was carried out on fifty sheep at the northwest coast and southeast of triangle Halayeb and Shalateen during the months of March and May 2018 and 2019 (average day time temperatures: 25–35 ◦C; relative humidity: 55–65%). Total RNA was extracted using easy-RED™ Total RNA Extraction Kit. The primers for qPCR were designed on the basis of prior sequence information available at National Center for Biotechnology Information (NCBI) for with the target HSP70 and 90 genes. The Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)) gene, housekeeping gene, was used for normalization qPCR data. The desired genes were amplified for relative expression measurements. Tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1 β, IL-6, IL-10, IL-12) were assayed. Results: The expression levels of the HSP70 and HSP90 genes and the genes in Abu Dlik sheep were observed to relatively up-regulated than those in Barki sheep. Abu Dlik breed exhibited an up-regulate mRNA level of Hsp70 and Hsp90 genes (1.70440938 vs 1.362954) while the Barki breed showed a down-regulated pattern (0.8550442 vs 0.4289764). In Abu Dlik ewes HSP70 gene exhibited a higher mRNA level than HSP90 mRNA. Conclusion and clinical relevance: Gene expression patterns of HSP 70 and HSP 90, as well as cytokines modulations, can be used as a biological marker and a reference point in animals to identify, manipulate and cross-breed for improving the genetic potential and adaptability in sheep which tolerates the harsh environmental conditions, especially the heat stress., and it is necessary to manage stress at a cellular level.

Standard guidelines for the publication of telomere qPCR results in evolutionary ecology.

Telomere length has been used as a proxy of fitness, aging and lifespan in vertebrates. In the last decade, dozens of articles reporting on telomere dynamics in the fields of ecology and evolution have been published for a wide range of taxa. With this growing interest, it is necessary to ensure the accuracy and reproducibility of telomere length measurement techniques. Real-time quantitative PCR (qPCR) is routinely applied to measure relative telomere length. However, this technique is highly sensitive to several methodological variables and the optimization of qPCR telomere assays remains highly variable between studies. Therefore, standardized guidelines are required to enable the optimization of robust protocols, and to help in judging the validity of the presented results. This review provides an overview of preanalytical and analytical factors that can lead to qPCR inconsistencies and biases, including: (a) sample type, collection and storage; (b) DNA extraction, storage and quality; (c) qPCR primers, laboratory reagents, and assay conditions; and (d) data analysis. We propose a minimum level of information for publication of qPCR telomere assays in evolutionary ecology considering the methodological pitfalls and sources of error. This review highlights the complexity of the optimization and validation of qPCR for telomere measurement per se, demonstrating the importance of transparency and clarity of reporting methodological details required for reliable, reproducible and comparable qPCR telomere assays. We encourage efforts to implement standardized protocols that ensure the rigour and quality of telomere dynamics studies.

Improved detection of Babesia bigemina from various geographical areas in Africa using quantitative PCR and reverse line blot hybridisation

Babesia bigemina is one of the aetiological agents of bovine babesiosis, which causes economic losses through mortality, loss of production and control costs. Effective means of detecting and quantifying B. bigemina in cattle populations is therefore important to inform control approaches. In order to examine the parasite genetic diversity in African countries, B. bigemina 18S rRNA genes from cattle from South Africa, Uganda and Angola were sequenced. The 25 distinct B. bigemina 18S rRNA gene sequences obtained in this study showed 99 to 100% identity with previously published sequences of strains from African and other continents. The sequences of the previously published B. bigemina 18S rRNA gene-specific quantitative PCR (qPCR) primers and probe, developed based on American and Asian strains, were conserved in the African B. bigemina sequences. The qPCR assay was evaluated using 10-fold and 2-fold serial dilutions of B. bigemina-infected erythrocytes to determine the efficiency and analytical sensitivity. The qPCR assay had an efficiency of 98.14 ± 1.71%, and the limit of detection was approximately 1.5 infected red blood cells (iRBCs) per microlitre (μl) of blood. The detection rate of B. bigemina from duplicates of field-collected blood samples from cattle from South Africa, Mozambique and Angola was 37% (30/81), 12% (6/49) and 50% (38/76), respectively. Reverse line blot hybridisation (RLB) results obtained from the same samples in previous studies, using a previously published B. bigemina-specific probe, detected the parasite DNA in only 1.5% (3/206) of the samples. A new B. bigemina-specific RLB oligonucleotide probe was designed in the hypervariable V4 region of the 18S rRNA gene. Screening of field blood samples from cattle showed that the new probe was specific, and its frequency of detection of B. bigemina was three times higher than the previously published probe. The qPCR assay and the newly developed B. bigemina-specific RLB probe provide good tools for epidemiological studies, which are essential in the control of bovine babesiosis.

Integrating host immune status, Labyrinthula spp. load and environmental stress in a seagrass pathosystem: Assessing immune markers and scope of a new qPCR primer set.

Recent trends suggest that marine disease outbreaks caused by opportunistic pathogens are increasing in frequency and severity. One such malady is seagrass wasting disease, caused by pathogens in the genus Labyrinthula. It is suspected that pathogenicity is intimately linked to the ability of the host to initiate defense responses; however, supportive evidence is lacking. To address this, we developed two techniques, including 1) a new qPCR-based pathogen detection method, and 2) an immune profiling panel via four host-biomarker assays (measuring peroxidase, exochitinase, polyphenol oxidase, and lysozyme activities). These techniques were then used to experimentally investigate the impact of environmental stressors (namely, elevated temperature and salinity) on host immunity and how immune status might affect susceptibility to Labyrinthula infection. In the first experiment, we subjected individual turtlegrass (Thalassia testudinum) shoots to short-term (7 d) abiotic stressors alone. In a second experiment, the same abiotic stressor conditions were followed by pathogen exposure (7 additional d), simulating a scenario where we attempt to isolate the impact of environmental stressors on the host seagrass species by removing the stressor as the pathogen is introduced. The qPCR assay successfully quantified the abundance of Labyrinthula spp. cells from both pure cultures and seagrass tissues across a broad range of predominately pathogenic strains, with high sensitivity. Immune enzyme assays revealed that all four biomarkers were constitutively active in turtlegrass individuals, but specific activities were largely unaffected by the chosen abiotic stressor conditions. We also identified positive correlations between pathogen load and two biomarkers (peroxidase, exochitinase), regardless of abiotic stress treatment, further demonstrating the potential utility of these biomarkers in future applications.

SpeciesPrimer: a bioinformatics pipeline dedicated to the design of qPCR primers for the quantification of bacterial species.

BackgroundQuantitative real-time PCR (qPCR) is a well-established method for detecting and quantifying bacteria, and it is progressively replacing culture-based diagnostic methods in food microbiology. High-throughput qPCR using microfluidics brings further advantages by providing faster results, decreasing the costs per sample and reducing errors due to automatic distribution of samples and reagents. In order to develop a high-throughput qPCR approach for the rapid and cost-efficient quantification of microbial species in complex systems such as fermented foods (for instance, cheese), the preliminary setup of qPCR assays working efficiently under identical PCR conditions is required. Identification of target-specific nucleotide sequences and design of specific primers are the most challenging steps in this process. To date, most available tools for primer design require either laborious manual manipulation or high-performance computing systems.ResultsWe developed the SpeciesPrimer pipeline for automated high-throughput screening of species-specific target regions and the design of dedicated primers. Using SpeciesPrimer, specific primers were designed for four bacterial species of importance in cheese quality control, namely Enterococcus faecium, Enterococcus faecalis, Pediococcus acidilactici and Pediococcus pentosaceus. Selected primers were first evaluated in silico and subsequently in vitro using DNA from pure cultures of a variety of strains found in dairy products. Specific qPCR assays were developed and validated, satisfying the criteria of inclusivity, exclusivity and amplification efficiencies.ConclusionIn this work, we present the SpeciesPrimer pipeline, a tool to design species-specific primers for the detection and quantification of bacterial species. We use SpeciesPrimer to design qPCR assays for four bacterial species and describe a workflow to evaluate the designed primers. SpeciesPrimer facilitates efficient primer design for species-specific quantification, paving the way for a fast and accurate quantitative investigation of microbial communities.

Phototrophic potential and form II ribulose-1,5-bisphosphate carboxylase/oxygenase expression in five organs of the fluted giant clam, Tridacna squamosa

Despite living in oligotrophic tropical waters, giant clams can grow to large sizes because they live in symbiosis with extracellular phototrophic dinoflagellates (zooxanthellae) and receive photosynthates from them. The physical presence of zooxanthellae in five organs (colorful outer mantle, whitish inner mantle, ctenidium, hepatopancreas and foot muscle) of Tridacna squamosa had been confirmed by microscopy, and high densities of zooxanthellae were detected in specific regions of the inner mantle and foot muscle. Symbiotic dinoflagellates use form II ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) to fix inorganic carbon during C3 photosynthesis. Using qPCR primers that were designed comprehensively against all known zooxanthellal form II RuBisCO gene sequences (rbcII) in existing databases, we demonstrated that the outer mantle of T. squamosa (TS) had the greatest phototrophic potential as reflected by its high zooxanthellal rbcII (TSZrbcII) transcript level, which varied among different regions of the outer mantle. The other four organs also expressed moderate levels of TSZrbcII, despite the lack of iridophores and direct light exposure. Importantly, light exposure led to significant increases in the protein abundance of TSZRBCII in the outer mantle but not the other four organs. Taken together, these results indicate that organs inside the mantle cavity had low phototrophic potentials, but zooxanthellae residing inside these organs might serve some unidentified functions to benefit the host.

P826 A predictive molecular classification developed in UC patients with active disease is observed consistently in a heterogeneous group of IBD patients

Abstract Background We have previously identified an unsupervised molecular classification of ulcerative colitis (UC) into two groups, UC1 and UC2, predictive of response to biologic therapy1. In that study, gene expression data in inflamed colonic biopsies from several published UC cohorts were used. UC1 is characterised by, for example, high expression of Cytochrome P450 26B1 (CYP26B1), calprotectin (S100A8) and interleukin 11 (IL11) and poor response to infliximab, which is also predicted by high expression of oncostatin M (OSM)2. In the current study the consistency of this classification was investigated in a heterogeneous group of inflammatory bowel disease (IBD) patients. Also, we sought to validate a quantitative polymerase chain reaction (qPCR) primer set as an alternative, more convenient methodology instead of microarray. Methods PCR primers for 7 differentially expressed genes that distinguished UC1 from UC2 in our microarray study were validated. OSM was also included. Separate gut biopsy samples (n = 44) from 15 patients, (8 Crohn’s disease, 7 UC), from different locations and at different time points, were analysed with qPCR. Results A heatmap of Pearson correlation coefficients (r) between gene expression levels and clinical factors for the pooled data was generated, Figure 1. Strong correlations, defined as 0.7 ≤ r ≤ 1.0, were found between OSM, CYP26B1, S100A8 and IL-11 (pairwise correlations were statistically significant, p < 0.00001). Similar inter-gene correlations were also observed within individual samples, (data not shown). Gene expression levels were not associated with inflammation, Figure 1. Conclusion These data demonstrate that the group genes we have previously identified as predictive of response to biologic therapy in UC, (CYP26B1, S100A8 and IL-11) plus OSM are also concordantly up-regulated in biopsy material from heterogeneous patients. Thus not only patients with active UC, but also other forms of IBD may be sub-grouped according to this gene expression pattern. The capacity of this gene expression profile to predict therapeutic response should therefore be tested in a broader range of IBD patients. The fact that the concordance of the up-regulation of these genes was independent of inflammation per se, supports the clinical significance of this molecular clustering. Establishment of qPCR-based characterisation into UC1 and UC2 presents a more convenient methodology for clinical stratification. References

PREVALENCE OF BOX TURTLE ADENOVIRUS IN EASTERN BOX TURTLES (TERRAPENE CAROLINA CAROLINA) PRESENTED TO A WILDLIFE REHABILITATION CENTER IN VIRGINIA, USA.

Eastern box turtles (Terrapene carolina carolina) are a native North American species with a declining population trend that may be attributable to habitat fragmentation, vehicle collisions, and disease. Adenoviral infections can cause significant morbidity and mortality in captive reptile populations. Adenoviruses have been documented in box turtles, but their occurrence and impact in wild populations are unknown. A disease survey was performed at The Wildlife Center of Virginia, USA, to assess the prevalence of box turtle adenovirus (BTAdV) in wild eastern box turtles and evaluate potential associations with clinical disease. Swabs from the oral cavity, including the choanal slit, and the cloaca were collected from 106 eastern box turtles from July 2015 through June 2016. The quantitative polymerase chain reaction (qPCR) primer detected both ornate box turtle adenovirus 1 and eastern box turtle adenovirus. The resulting qPCR adenovirus prevalence was 55.7% (n = 59). Most animals (99.3%) that tested positive for BTAdV had fewer than 100 viral copies/ng DNA. This study did not find a statistically significant association between cause of admission, age, sex, outcome, and BTAdV qPCR status. However, the probability of BTAdV detection was 1.5 times higher in rehabilitation turtles compared with wild turtles (P = 0.01). Albumin was significantly lower in qPCR BTAdV-positive turtles (P = 0.007). Hypoalbuminemia is not generally associated with adenovirus infections in other species, and no obvious clinical cause for this abnormality was identified. The results of this study suggest that eastern box turtles may harbor BTAdV infections at low levels and that infection is rarely associated with clinical disease, potentially identifying BTAdV as a host-adapted pathogen. Future studies should focus on this pathogen's ability to induce clinical disease and its potential impact on recovery efforts for this species.

The quantification of antibody elements and receptors subunit expression using qPCR: The design of VH, VL, CH, CL, FcR subunits primers for a more holistic view of the immune system

The expression levels of immunoglobulin elements and their receptors are important markers for health and disease. Within the immunoglobulin locus, the constant regions and the variable region families are associated with certain pathologies, yet a holistic view of the interaction between the expressions of the multiple genes remain to be fully characterized. There is thus an important need to quantify antibody elements, their receptors and the receptor subunits in blood (PBMC cDNA) for both screening and detailed studies of such associations. Leveraging on qPCR, we designed primers for all Vκ1-6, VH1-7, Vλ1-11, nine CH isotypes, Cκ, Cκ, Cλ1 &3, FcεRI α,β, and γ subunits, all three FcγR and their subunits, and FcαR. Validating this on a volunteer PBMC cDNA, we report a qPCR primer set repertoire that can quantify the relative expression of all the above genes to the GAPDH housekeeping gene, with implications and uses in both clinical monitoring and research.

1786. An Automated Method to Assess Oligonucleotide Primer and Probe Complementarity to Genomic Targets in Infectious Disease qPCR Assays

BackgroundSuccess of real-time TaqMan PCR (qPCR) in detecting pathogen targets and quantifying pathogen load is dependent upon frequent assay monitoring. This is due to i) the high degree of complementarity needed between primers / probes and genomic targets for assay accuracy and ii) natural pathogen variation and evolution. Failure to monitor and refine may result in false negativity or under quantification. Here we present a bioinformatics tool to identify potential problems resulting from newly discovered genomic mutations in primer/probe regions.MethodsThe tool performs an unbiased and automated search of the NCBI database, collects relevant genomic sequences based on user-defined Taxon-ID and executes a Python program to discard synthetic sequences. A profile of primer-probe sequence complementarity to targets is then generated. While the tool can be used for any microbe, here we present results for our laboratory’s cytomegalovirus (CMV) qPCR primer-probe analysis. In addition, our laboratory’s traditional approach utilizing alignment software was performed (download of all CMV sequences (~10,000) followed by iterative alignment building of these against our primers and probes). The amount of time to perform the automated and manual methods was recorded.ResultsThe tool retrieved 8,732 sequences from NCBI and compared these to the CMV qPCR primers and probes. The tool found 2,501 alignments between the primers / probes and the downloaded genomic data (~15 minutes to finish (6 CPUs)). A total of 64% (1,624/2,501) of BLASTn alignments were exact matches between all primers / probes and viral genomic sequences. 17.5% (439/2,501) of alignments had 1 mismatch at either 5’ or 3’ terminus, and 1% (25/2,501) of alignments had two mismatches with the primers / probes. Similar results were found using a primarily manual approach (which took approx. 5 hours computing time and 20 hours of labor).ConclusionThis new bioinformatics approach performed indistinguishably vs. a manual approach and did so in minutes rather than days. Both methods led to the conclusion that, by virtue of our design involving overlapping primers and probes, none of the identified mismatches are predicted to lead to false negativity or under quantification in our current CMV qPCR assay.Disclosures All authors: No reported disclosures.