Molecular Assays For Detection Research Articles

Influenza A, Influenza B, human respiratory syncytial virus and SARSCoV-2 molecular diagnostics and epidemiology in the post COVID-19 era

BackgroundThe concurrent circulation of SARS-CoV-2 with other respiratory viruses is unstoppable and represents a new diagnostic reality for clinicians and clinical microbiology laboratories. Multiplexed molecular testing on automated platforms that focus on the simultaneous detection of multiple respiratory viruses in a single tube is a useful approach for current and future diagnosis of respiratory infections in the clinical setting.MethodsTwo time periods were included in the study: from February to April 2022, an early 2022 period, during the gradual lifting of COVID-19 prevention measures in the country, and from October 2022 to April 2023, the 2022/23 respiratory infections season. We analysed a total of 1,918 samples in the first period and 18,131 respiratory samples in the second period using a multiplex molecular assay for the simultaneous detection of Influenza A (Flu-A), Influenza B (Flu-B), Human Respiratory Syncytial Virus (HRSV) and SARS-CoV-2.ResultsThe results from early 2022 showed a strong dominance of SARS-CoV-2 infections with 1,267/1,918 (66.1%) cases. Flu-A was detected in 30/1,918 (1.6%) samples, HRSV in 14/1,918 (0.7%) samples, and Flu-B in 2/1,918 (0.1%) samples. Flu-A/SARS-CoV-2 co-detections were observed in 11/1,267 (0.9%) samples, and HRSV/SARS-CoV-2 co-detection in 5/1,267 (0.4%) samples. During the 2022/23 winter respiratory season, SARS-CoV-2 was detected in 1,738/18,131 (9.6%), Flu-A in 628/18,131 (3.5%), Flu-B in 106/18,131 (0.6%), and HRSV in 505/18,131 (2.8%) samples. Interestingly, co-detections were present to a similar extent as in early 2022.ConclusionThe results show that the multiplex molecular approach is a valuable tool for the simultaneous laboratory diagnosis of SARS-CoV-2, Flu-A/B, and HRSV in hospitalized and outpatients. Infections with Flu-A/B, and HRSV occurred shortly after the COVID-19 control measures were lifted, so a strong reoccurrence of various respiratory infections and co-detections in the post COVID-19 period was to be expected.

Comparative evaluation of Anyplex II HPV28 and Allplex HPV28 molecular assays for human papillomavirus detection and genotyping in anogenital cancer screening.

Persistent infection with high-risk human papillomavirus (HPV) is recognized as the main cause for the development of anogenital cancers. This study prospectively evaluated the diagnostic performance of the novel Allplex-HPV28 assay with the Anyplex-II-HPV28 to detect and genotype HPV in 234 consecutive swabs and 32 biopsies of the anogenital tract from 265 patients with atypical findings in cytomorphological screening. Agreement in HPV-DNA detection between the Anyplex-II and Allplex-HPV28 assays was 99%. There was a notable diversity in the HPV-virome, with the most prevalent high-risk HPV types being 16, 53, 66, and 68. The agreement rates for detecting these genotypes exceeded 93% between the Anyplex-II and Allplex-HPV28 assays. Discrepancies in test results were solely noted for Anyplex-II-HPV28 results with a low signal intensity of "+", and for Allplex-HPV28 results with cycle thresholds of ≥36. The semi-quantitative analysis of HPV-DNA loads showed significant agreement between the Anyplex-II-HPV28 and Allplex-HPV28 assays (p < 0.001). Furthermore, HPV-DNA detection rates and mean HPV-DNA loads significantly correlated with the grade of abnormal changes identified in cytopathological assessment, being highest in cases of HSIL, condyloma accuminatum, and squamous cell carcinoma. Overall agreement rates for detecting specific HPV-types among the Anyplex-II and Allplex-HPV28 assays exceeded 99.5% in cases of atypical squamous cells, condyloma accuminatum, and squamous cell carcinoma. The novel Allplex-HPV28 assay shows good diagnostic performance in detecting and genotyping HPV commonly associated with anogenital cancers. Consequently, this assay could offer substantial potential for incorporation into future molecular screening programs for anogenital cancers in clinical settings.

Molecular genotyping of Babesia caballi

Babesia caballi is an intra-erythrocytic parasite causing equine piroplasmosis. Three B. caballi genotypes (A, B, and C) have been identified based on the 18 S rRNA and rhoptry-associated protein (rap-1) gene sequences. These variant parasite genotypes compromise the diagnostic utility of the WOAH-recommended serological assays in declaring horses free of equine piroplasmosis. Although a gene encoding a spherical body protein 4 (sbp4) has recently been identified as a potential antigen for the serological detection of B. caballi, the ability of this antigen to detect the different geographical strains has not been determined. The molecular distinction between variant B. caballi genotypes is limited and therefore we developed molecular typing assays for the rapid detection and quantification of distinct parasite genotypes. Field samples were screened for the presence of B. caballi using an established multiplex equine piroplasmosis qPCR assay. In this study, B. caballi genotype A was not detected in any field samples screened. However, phylogenetic analysis of the amplified sbp4 and 18 S rRNA genes confirmed the phylogenetic groupings of the South African isolates into either B. caballi genotypes B or C. A multiple sequence alignment of the sbp4 gene sequences obtained in this study together with the published sbp4 sequences representing B. caballi genotype A, were used to identify conserved regions within the gene to design three primer pairs and three genotype-specific TaqMan minor-groove binder (MGB™) probes. The qPCR assays were shown to be specific and efficient in the detection and differentiation between B. caballi genotypes A, B, and C and could be used as a diagnostic assay to prevent the unintentional spread of variant B. caballi genotypes globally.

Development of recombinase polymerase amplification-based colorimetric detection assay for rapid identification of invasive cassava mealybug, Phenacoccus manihoti Matile-Ferrero

Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), is an economically important invasive cassava pest responsible for the massive devastation of cassava in Asia and African continent. Initially, identifying this invasive pest posed challenges because it closely resembled native mealybug species. Additionally, the traditional morphological identification process is labor-intensive and time-consuming. Detecting invasive pests at an early stage is crucial, hence development of a rapid detection assay is essential. In the current study, we have developed a simple, rapid, sensitive, and efficient molecular detection assay for P. manihoti based on Recombinase Polymerase Amplification (RPA). The primers for the RPA assay were designed using unique nucleic acid sequences of P. manihoti, and the protocol was standardized. Specificity test demonstrated that the RPA assay could amplify DNA of P. manihoti only, and no amplification was observed in six other mealybug species. The specificity of assay was confirmed using SYBR green-based colorimetric detection and gel electrophoresis where positive samples showed 195 bp amplicon size in P. manihoti samples. The assay successfully amplified P. manihoti DNA in thirty minutes at an annealing temperature of 41° C in a water bath and displayed a sensitivity of 72.5 picograms per microliter. The assay's simplicity, rapidity, and high sensitivity make it a valuable tool for detecting and monitoring P. manihoti in quarantine stations and facilitating in development of a portable diagnostic kit.

Development of a reverse transcription loop-mediated isothermal amplification assay with novel quantitative pH biosensor readout method for SARS-CoV-2detection.

Reverse transcription loop-mediated isothermal amplification (RT-LAMP) is a molecular amplification method that can detect SARS-CoV-2 in a shorter time than the current gold-standard molecular diagnostic reverse transcription-polymerase chain reaction (RT-PCR). However, previously developed RT-LAMP assays have mostly relied on highly subjective visual colorimetric interpretation. In this study, an RT-LAMP assay was developed with quantitative measurement of reaction pH using a novel portable pH biosensor compared to qualitative colorimetric interpretation and gel electrophoresis, with 57 clinical COVID-19 samples used for validation of the test. The LoD of the assay is 103 copies/μL. The highest sensitivity was found in the qualitative methods (93.75%), while the highest specificity and likelihood ratio was found in the pH sensor (87.5% and 6.72). On the sensor measurement, a significant difference (p < 0.0001) was observed between the average pH of the RT-PCR (+) COVID-19 (6.15 ± 0.27), while the average pH of the RT-PCR (-) samples (6.72 ± 0.22). Correlation analysis revealed a strong correlation (r = 0.78, p < 0.0001) between the Ct values obtained from RT-PCR with the biosensor pH readout. RT-LAMP with the quantitative pH sensor readout method has the potential to be further developed as an objective molecular assay for rapid and simple detection of SARS-CoV-2.

A One-Step RPA-CRISPR Assay Using crRNA Based on Suboptimal Protospacer Adjacent Motif for Vibrio vulnificus Detection.

Vibrio vulnificus is a hazardous foodborne pathogen responsible for approximately 95% of seafood-related deaths. This highlights the urgent requirement for specialized detection tools to be developed and used by food enterprises and food safety authorities. The DETECTR (DNA endonuclease targeted CRISPR trans reporter) system that combines CRISPR/Cas and recombinase polymerase amplification (RPA) has been utilized to develop a molecular detection assay for V. vulnificus. However, because the incompatibility between RPA and Cas12a cleavage has not been addressed, it is a two-step assay that lacks convenience and presents contamination risk. Here, we developed a one-step RPA-CRISPR assay for V. vulnificus using a special crRNA targeting a sequence with a suboptimal protospacer adjacent motif (PAM). The entire assay, conducted at 37°C, takes only 40-60 min, yields results visualized under blue light, and exhibits exceptional specificity and sensitivity (detecting 4 pathogen genome copies per reaction). This study offers a valuable tool for detecting V. vulnificus, aiding in foodborne infection prevention, and exemplifies one-step RPA-CRISPR assays managing Cas-cleavage activity through PAM adjustments.

NOVEL TRAP CONFIGURATION FOR LIVE CAPTURE OF MOSQUITOES

Diverse mosquito traps are available for mosquito and arbovirus surveillance. The delicate nature of the mosquito body makes them vulnerable to damage as they pass through the trap's fan, which can lead to rapid desiccation or mortality within the capture chamber. This can negatively affect surveillance accuracy, impacting both the precise identification of mosquitoes and the reliable execution of molecular assays for arbovirus detection. In this study, we report a novel modification to three widely used mosquito traps: CDC light trap, BG-Sentinel trap, and CDC gravid trap, incorporating a mesh funnel and updraft design to address these issues. We compared updraft and downdraft configurations of light traps under field conditions and compared the effectiveness of the modified BG and gravid trap to unaltered counterparts in semi-field environments. Subsequently, we conducted field validation of modified mosquito traps to assess their trapping effectiveness in terms of mosquito abundance and species composition in coastal forest and suburban areas. Our findings revealed that there was no significant difference in trapping effectiveness between different fan configurations. The adaptation made to the BG trap exhibited higher recapture rates of Culex quinquefasciatus and Aedes albopictus in comparison to the unmodified BG-Sentinel trap. The modification of the gravid trap was equivalent to unaltered CDC gravid trap. During our field trial, the modified light traps had a higher collection rate of mosquitoes with a wider spectrum of species diversity than modified BG or gravid traps, regardless of site. The modified BG traps captured more arbovirus vector species (Culex and Aedes species), with an increase in Ae. albopictus (11 times) and Ae. aegypti (1.75 times) when compared to the light traps. The modified gravid traps mostly collected Culex spp., accounting for over 47% of the collected mosquitoes. The results indicate that the novel trap configuration preserves trap functionality and improves specimen quality by avoiding the death and dismemberment of collected mosquitoes.

Multicenter evaluation of an automated, multiplex, RNA-based molecular assay for detection of ALK, ROS1, RET fusions and MET exon 14 skipping in NSCLC.

The current study assessed the performance of the fully automated RT-PCR-based Idylla™ GeneFusion Assay, which simultaneously covers the advanced non-small cell lung carcinoma (aNSCLC) actionable ALK, ROS1, RET, and MET exon 14 rearrangements, in a routine clinical setting involving 12 European clinical centers. The Idylla™ GeneFusion Assay detects fusions using fusion-specific as well as expression imbalance detection, the latter enabling detection of uncommon fusions not covered by fusion-specific assays. In total, 326 archival aNSCLC formalin-fixed paraffin-embedded (FFPE) samples were included of which 44% were resected specimen, 46% tissue biopsies, and 9% cytological specimen. With a total of 179 biomarker-positive cases (i.e., 85 ALK, 33 ROS1, 20 RET fusions and 41 MET exon 14 skipping), this is one of the largest fusion-positive datasets ever tested. The results of the Idylla™ GeneFusion Assay were compared with earlier results of routine reference technologies including fluorescence in situ hybridization, immunohistochemistry, reverse-transcription polymerase chain reaction, and next-generation sequencing, establishing a high sensitivity/specificity of 96.1%/99.6% for ALK, 96.7%/99.0% for ROS1, 100%/99.3% for RET fusion, and 92.5%/99.6% for MET exon 14 skipping, and a low failure rate (0.9%). The Idylla™ GeneFusion Assay was found to be a reliable, sensitive, and specific tool for routine detection of ALK, ROS1, RET fusions and MET exon 14 skipping. Given its short turnaround time of about 3 h, it is a time-efficient upfront screening tool in FFPE samples, supporting rapid clinical decision making. Moreover, expression-imbalance-based detection of potentially novel fusions may be easily verified with other routine technologies without delaying treatment initiation.

All‐in‐one Xylella detection and identification: A nanopore sequencing‐compatible conventional PCR

AbstractXylella fastidiosa is a plant‐pathogenic bacterium that poses a serious threat to the production of economically important plant species including grapes, almonds, olives and a broad range of amenity plants, causing significant economic losses worldwide. While multiple molecular detection assays have been developed for X. fastidiosa, there is a lack of molecular tools available for detection and differentiation of the closely related pear pathogen, Xylella taiwanensis. In this study, we present a novel conventional PCR assay with primers that can amplify both Xylella species. The amplified product could be sequenced and used for discrimination between the two species and the subspecies within the fastidiosa species. This PCR assay was designed using a genome‐informed approach to target the ComEC/Rec2 gene of both Xylella species, ensuring a higher specificity than other previously developed PCR assays. A test performance study across five national plant diagnostic laboratories in Australia and New Zealand demonstrated this assay's high sensitivity and specificity to all known species and subspecies within the Xylella genus. This PCR assay can be used for Xylella identification at the species and subspecies level and is compatible with Sanger sequencing and nanopore sequencing for rapid turnaround time. The newly developed conventional PCR assay presented here offers rapid detection and accurate identification of both Xylella species from plant, insect vector or bacterial samples, enabling timely implementation of biosecurity measures or disease management responses.

Enhancing sensitivity of qPCR assays targeting Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae by using a mutant Taq DNA polymerase

AimsStreptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae are important causes of bacterial meningitis. In this study, the DNA binding site of the wild type Taq DNA polymerase was modified to produce a mutant enzyme with enhanced DNA affinity and PCR performance. The engineered and the wild type enzymes were integrated into qPCR-based assays for molecular detection of S. pneumoniae, N. meningitidis, H. influenzae, and serogroups and serotypes of these three pathogens. MethodsBio-Speedy® Bacterial DNA Isolation Kit (Bioeksen R&D Technologies, Turkiye) and 2× qPCR-Mix for hydrolysis probes (Bioeksen R&D Technologies, Turkiye) and CFX96 Instrument (Biorad Inc., USA) were used for all molecular analyses. Spiked negative clinical specimens were tested using the developed qPCR assays and the culture-based conventional methods for the analytical performance evaluation. ResultsAll qPCR assays did not produce any positive results for the samples spiked with potential cross-reacting bacteria. Limit of detection (LOD) of the assays containing the mutant enzyme was 1 genome/reaction (10 cfu/mL sample) which is at least 3 times lower than the previously reported LOD levels for DNA amplification based molecular assays. LODs for the spiked serum and cerebrospinal fluid (CSF) samples decreased 2.3–4.7 and 1.2–3.5 times respectively when the mutant enzyme was used instead of the wild type Taq DNA polymerase. ConclusionsIt is possible to enhance analytical sensitivity of qPCR assays targeting the bacterial agents of meningitis by using an engineered Taq DNA polymerase. These qPCR-based assays can be used for direct detection and serogrouping / serotyping of S. pneumoniae, N. meningitidis and H. influenzae at concentrations close to the lower limit of medical decision point.

Challenging the gold standard: the limitations of molecular assays for detection of Mycobacterium tuberculosis heteroresistance

ObjectivesHeteroresistant infections are defined as infections in which a mixture of drug-resistant and drug-susceptible populations are present. In Mycobacterium tuberculosis (M. tb), heteroresistance poses a challenge in diagnosis and has...

Microscopic and molecular investigation of vector borne haemoprotozoan diseases in dromedary camel of North Gujarat.

Vector borne haemoprotozoan diseases comprise diverse group of single celled organism transmitted by haematophagus invertebrates. The current study was aimed at identification of major haemoprotozoan (Babesia, Theileria and Trypanosoma) in dromedary camel of North Gujarat region using microscopy and Polymerase Chain Reaction (PCR). A total of 234 blood samples were screened by the microscopic and molecular detection assays. Molecular prevalence studies of Theileria, Trypanosoma spp and Babesia was undertaken using 18s ribosomal DNA, RoTat 1.2 and SS rRNA gene respectively. The data relating to microscopic and molecular prevalence along with associated risk factors were analysed by statistical methods. The overall prevalence of hamoprotozoan disease based on microscopic and molecular investigation was 23.50%. The sensitivity and specificity (95% Confidence Interval) of PCR assay was 100% in comparison to microscopy (45.45% and 100%). The kappa coefficient between PCR and microscopy indicated good level of agreement with a value of 0.704 and SE of 0.159. Despite holding much significance to the animal sector, little work has been undertaken in regional part of India regarding camel parasites. The present paper offers the first preliminary research data investigating haemoprotozoan disease using parasitological and molecular methods in camels in the region.

Comparison of molecular and microbiological detection rates of Mycobacterium tuberculosis and prevalence of SARS-CoV-2 variants in Monterrey, Mexico

BackgroundTuberculosis (TB) is a severe global health problem, with high drug resistance rates. The emergence of the coronavirus disease 2019 (COVID-19) pandemic caused worldwide setback progress in TB control. Our aim was to compare detection rates of Mycobacterium tuberculosis at different COVID-19 pandemic waves. MethodsPatients (n = 1800) were evaluated using microbiological and molecular assays for mycobacterial detection in a hospital from Monterrey, Mexico. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detected by real-time PCR. Data from existing reports of circulating SARS-CoV-2 variants was compared to data of TB prevalence. ResultsThe prevalence of TB was 30.4%. Compared to pre-pandemic, the detection rate of mycobacteria was higher during the first wave. The co-infection of Mycobacterium tuberculosis complex (MTC) and SARS-CoV-2 occurred in seven patients. MTC cases showed several waves which might depend on the prevalence of specific SARS-CoV-2 variants. ConclusionThe COVID-19 pandemic impacted on TB detection on our population, although it is still uncertain if it was mostly due to the influence of specific SARS-CoV-2 variants or to restrictions measures in the region. Public health measures should include the combination of TB and COVID-19 diagnostic screening in TB-endemic settings, such as ours, to restore TB control attempts.

Comparison of Circulating Tumor DNA Assays for Molecular Residual Disease Detection in Early-Stage Triple-Negative Breast Cancer.

Detection of circulating tumor DNA (ctDNA) in patients who have completed treatment for early-stage breast cancer is associated with a high risk of relapse, yet the optimal assay for ctDNA detection is unknown. The cTRAK-TN clinical trial prospectively used tumor-informed digital PCR (dPCR) assays for ctDNA molecular residual disease (MRD) detection in early-stage triple-negative breast cancer. We compared tumor-informed dPCR assays with tumor-informed personalized multimutation sequencing assays in 141 patients from cTRAK-TN. MRD was first detected by personalized sequencing in 47.9% of patients, 0% first detected by dPCR, and 52.1% with both assays simultaneously (P < 0.001; Fisher exact test). The median lead time from ctDNA detection to relapse was 6.1 months with personalized sequencing and 3.9 months with dPCR (P = 0.004, mixed-effects Cox model). Detection of MRD at the first time point was associated with a shorter time to relapse compared with detection at subsequent time points (median lead time 4.2 vs. 7.1 months; P = 0.02). Personalized multimutation sequencing assays have potential clinically important improvements in clinical outcome in the early detection of MRD.

A real-time colourimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the rapid detection of highly pathogenic H5 clade 2.3.4.4b avian influenza viruses

ABSTRACT Highly pathogenic avian influenza viruses (HPAIV) are a major threat to the global poultry industry and public health due to their zoonotic potential. Since 2016, Europe and France have faced major epizootics caused by clade 2.3.4.4b H5 HPAIV. To reduce sample-to-result times, point-of-care testing is urgently needed to help prevent further outbreaks and the propagation of the virus. This study presents the design of a novel real-time colourimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the detection of clade 2.3.4.4b H5 HPAIV. A clinical validation of this RT-LAMP assay was performed on 198 pools of clinical swabs sampled in 52 poultry flocks during the H5 HPAI 2020–2022 epizootics in France. This RT-LAMP assay allowed the specific detection of HPAIV H5Nx clade 2.3.4.4b within 30 min with a sensitivity of 86.11%. This rapid, easy-to-perform, inexpensive, molecular detection assay could be included in the HPAIV surveillance toolbox.

Molecular diagnostic assay for pre-harvest detection of Tilletia indica infection in wheat plants.

The current study describes a new diagnostic method for the rapid and accurate detection of Tilletia indica, the pathogen accountable for causing Karnal bunt (KB) disease in wheat. This method uses quantitative real-time polymerase chain reaction (qPCR) and a primer set derived from glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene of T. indica to identify the presence of the pathogen. The qPCR assay using this primer set was found highly sensitive, with a limit of detection (LOD) value of 4 pg of T. indica DNA. This level of sensitivity allows for the detection of the pathogen even in cases of different growth stages of wheat, where no visible symptoms of infection on the wheat plants can be seen by naked eyes. The study also validated the qPCR assay on ten different wheat cultivars. Overall, this study presents a valuable molecular tool for rapid, specific and sensitive detection of KB fungus in wheat host. This method has practical applications in disease management, screening of wheat genotypes against KB and can aid in the development of strategies to mitigate the impact of Karnal bunt disease on wheat production.

Diagnostic assay for molecular detection of Bipolaris maydis and Stenocarpella maydis for safe exchange and long-term conservation of maize germplasm

Maize is a versatile multi-purpose crop used as a feed and food crop and is one of the most extensively grown and traded crops globally. The maize cultivation is greatly influenced by several seed-borne fungal pathogens including Bipolaris maydis and Stenocarpella maydis. Keeping the potential risks associated with movement of seeds, a conventional and qPCR based reliable and sensitive method for detection of B. maydis and S. maydis was developed. Four sets of specific primers derived from kilbournase gene were developed for detection and quantification of S. maydis, whereas, six sets of specific primers were developed from internal transcribed spacer (ITS) region for detection of B. maydis. The specificity and sensitivity of the primers developed for both the fungal pathogens were tested and the primers were found specific to the target pathogens and are able to detect up to 0.1 pg of genomic DNA. A duplex PCR assay for simultaneous detection of these fungal pathogens was successfully established using highly specific and sensitive primer sets, BmayITS1F&5R specific to B. maydis and DMKB4F&4R specific to S. maydis. The primers produced specific size of amplicons in duplex as well as individually for respective target pathogens. The developed protocol in the present study could be utilized effectively for detection and quantification of these pathogens to facilitate the quick quarantine processing, monitor seed health and seed certification thereby preventing infected maize from entering into food and feed chain and also to facilitate their long-term safe conservation.

B-268 Validation of a New Real-Time PCR Test for the Detection of Mpox Virus on the BD MAXTM System

Abstract Background Enabling labs to rapidly respond to unexpected healthcare challenges is the kind of situations for which the BD MAX™ open system reagent suite is designed. Therefore, after the monkeypox outbreak in non-endemic countries on May 2022, development of a molecular assay for monkeypox detection on the BD MAXTM System was initiated. Methods VIASURE Monkeypox virus Real Time PCR Reagents for BD MAX™ System was designed for the qualitative detection of DNA from monkeypox virus in human skin lesion swabs in VTM/UTM obtained from individuals suspected of monkeypox infection. The Limit of Detection (LoD) was determined by testing a 3-fold dilution series across 5 concentrations. The lowest concentration with 100% detection was tested with an additional 20 replicates. The preliminary LoD was confirmed with a ≥95% detection with 20 replicates. Then, a fully contrived clinical evaluation was performed. Each contrived clinical specimen was prepared using a unique natural clinical specimen matrix (lesion swabs). Twenty (20) of the clinical specimens were prepared at 1-2X LoD, ten (10) were prepared at 3-5X LoD, and thirty (30) were tested as negative samples. Results The lowest detectable concentration of virus at which &amp;gt;95% of all replicates test positive (LoD) was 288 copies/mL. The results for the contrived clinical evaluation are shown in Table 1. 19/20 (≥95%) low positive specimens (1-2xLoD) and 20/20 (100%) moderate positive specimens (3-5x LoD) were detected demonstrating the functionality of the test. Conclusion VIASURE Monkeypox virus Real Time PCR Reagents for BD MAX™ System provides results in a short time and requires less than one minute of hands-on time per sample due to integration of fully automated extraction and thermocycling steps. An additional clinical testing of positive natural clinical specimens must be performed to complete evidence that this product is for the purpose and the population for which it is intended.

Diagnosis of α-thalassaemia by colorimetric gap loop mediated isothermal amplification

α-Thalassaemia is an inherited haemoglobin disorder that results from the defective synthesis of α-globin protein. Couples whom both carry the α-thalassaemia 1 gene are at risk of having a foetus with the most severe thalassaemia, Hb Bart’s hydrops fetalis, with a risk of maternal mortality. However, haematological parameters alone cannot distinguish between a α-thalassaemia 1 carrier and a homozygous α-thalassaemia 2, in which one α-globin gene has been deleted on each chromosome. A rapid and accurate molecular detection assay is essential for prevention of the disease in populations where α-thalassaemia 1 is common. Multiplex Gap-PCR analysis is widely used for diagnosis of α-thalassaemia. However, the technique requires a thermocycler and post-amplification processing, which limits its application in primary care or in rural areas in developing countries. Loop mediated isothermal amplification (LAMP) amplifies target DNA at a constant temperature and does not require a thermocycler. This study developed a colorimetric Gap-LAMP using malachite green to allow naked eye visualization of two deletional α-thalassaemia 1 commonly found in Asian populations, the Southeast Asian type (--SEA) and the Thai type (--THAI) deletions. The Gap-LAMP was performed on DNA samples from 410 individuals carrying various α-thalassaemia gene defects with 100% concordance with conventional Gap-PCR analysis. This method eliminates post-amplification processing or the use of expensive sophisticated equipment and allows screening large populations for the prevention and control of α-thalassaemia.

Identification of sequence mutations in Phytophthora cactorum genome associated with mefenoxam resistance and development of a molecular assay for the mutant detection in strawberry (F. × ananassa)

Phytophthora crown rot (PhCR) caused by Phytophthora cactorum is one of the most damaging diseases of strawberry worldwide. Mefenoxam is one of the major fungicides currently used to manage PhCR. However, the emergence and spread of resistant isolates have made controlling the pathogen in the field problematic. In the present study, using whole genome sequencing analysis, mutations associated with mefenoxam-resistant isolates were identified in six different genomic regions of P. cactorum. The 95.54% reads from a sensitive isolate pool and 95.65% from a resistant isolate pool were mapped to the reference genome of P. cactorum P414. Four point mutations were in coding regions while the other two were in noncoding regions. The genes harboring mutations were functionally unknown. All mutations present in resistant isolates were confirmed by sanger sequencing of PCR products. For the rapid diagnostic assay, SNP-based high-resolution melting (HRM) markers were developed to differentiate mefenoxam-resistant P. cactorum from sensitive isolates. The HRM markers R3-1F/R3-1R and R2-1F/R2-1R were suitable to differentiate both sensitive and resistant profiles using clean and crude DNA extraction. None of the mutations associated with mefenoxam resistance found in this study were in the RNA polymerase subunit genes, the hypothesized target of this compound in oomycetes. Our findings may contribute to a better understanding of the mechanisms of resistance of mefenoxam in oomycetes since serves as a foundation to validate the candidate genes as well as contribute to the monitoring of P. cactorum populations for the sustainable use of this product.