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Genome-targeted enrichment and sequencing of human-infecting Cryptosporidium spp.

Cryptosporidium spp. are parasites that cause severe illness in vulnerable human populations. Obtaining pure and sufficient Cryptosporidium DNA from clinical and environmental samples is a challenging task. Oocysts shed in available fecal samples can be limited in quantity, require purification (biased towards dominant strains), and yield limited DNA (&#x2009;<&#x2009;40 fg/oocyst). Here, we use updated genomic sequences from a broad diversity of Cryptosporidium species that have been found to infect humans (C. cuniculus, C. hominis, C. meleagridis, C. parvum, C. tyzzeri, and C. viatorum) to develop and validate a set of 100,000 RNA baits (CryptoCap_100k) with the aim of enriching Cryptosporidium DNA from varied samples. Compared to unenriched libraries, CryptoCap_100k increases the percentage of reads mapping to target genome sequences, increases the depth and breadth of genome coverage, and facilitates analyses of genetic variants in many samples, while decreasing overall costs.

Cryptosporidium

GENOME TARGETED ENRICHMENT AND SEQUENCING OF HUMAN-INFECTING CRYPTOSPORIDIUM spp.

Cryptosporidium spp. are parasites that cause severe illness in vulnerable human populations. Obtaining pure and sufficient Cryptosporidium DNA from clinical and environmental samples is a challenging task. Oocysts shed in available fecal samples can be limited in quantity, require purification (biased towards dominant strains), and yield limited DNA (<40 fg/oocyst). Here, we use updated genomic sequences from a broad diversity of human-infecting Cryptosporidium species ( C. cuniculus , C. hominis , C. meleagridis , C. parvum , C. tyzzeri , and C. viatorum ) to develop and validate a set of 100,000 RNA baits (CryptoCap_100k) with the aim of enriching Cryptosporidium spp. DNA from varied samples. Compared to unenriched libraries, CryptoCap_100k increases the percentage of reads mapping to target genome sequences, increases the depth and breadth of genome coverage and the reliability of detecting species and mixed infections within a sample, and allows assessment of genetic variation via SNP calling, while decreasing costs.

Journal Article

WHOLE GENOME TARGETED ENRICHMENT AND SEQUENCING OF HUMAN-INFECTING CRYPTOSPORIDIUM spp.

Cryptosporidium spp. are protozoan parasites that cause severe illness in vulnerable human populations. Obtaining pure Cryptosporidium DNA from clinical and environmental samples is challenging because the oocysts shed in contaminated feces are limited in quantity, difficult to purify efficiently, may derive from multiple species, and yield limited DNA (<40 fg/oocyst). Here, we develop and validate a set of 100,000 RNA baits (CryptoCap_100k) based on six human-infecting Cryptosporidium spp. (C. cuniculus, C. hominis, C. meleagridis, C. parvum, C. tyzzeri, and C. viatorum) to enrich Cryptosporidium spp. DNA from a wide array of samples. We demonstrate that CryptoCap_100k increases the percentage of reads mapping to target Cryptosporidium references in a wide variety of scenarios, increasing the depth and breadth of genome coverage, facilitating increased accuracy of detecting and analyzing species within a given sample, while simultaneously decreasing costs, thereby opening new opportunities to understand the complex biology of these important pathogens.

Journal Article

FLASH-TB: an Application of Next-Generation CRISPR to Detect Drug Resistant Tuberculosis from Direct Sputum.

Offering patients with tuberculosis (TB) an optimal and timely treatment regimen depends on the rapid detection of Mycobacterium tuberculosis (Mtb) drug resistance from clinical samples. Finding Low Abundance Sequences by Hybridization (FLASH) is a technique that harnesses the efficiency, specificity, and flexibility of the Cas9 enzyme to enrich targeted sequences. Here, we used FLASH to amplify 52 candidate genes probably associated with resistance to first- and second-line drugs in the Mtb reference strain (H37Rv), then detect drug resistance mutations in cultured Mtb isolates, and in sputum samples. 92% of H37Rv reads mapped to Mtb targets, with 97.8% of target regions covered at a depth&#x2009;&#x2265;&#x2009;10X. Among cultured isolates, FLASH-TB detected the same 17 drug resistance mutations as whole genome sequencing (WGS) did, but with much greater depth. Among the 16 sputum samples, FLASH-TB increased recovery of Mtb DNA compared with WGS (from 1.4% [IQR 0.5-7.5] to 33% [IQR 4.6-66.3]) and average depth reads of targets (from 6.3 [IQR 3.8-10.5] to 1991 [IQR 254.4-3623.7]). FLASH-TB identified Mtb complex in all 16 samples based on IS1081 and IS6110 copies. Drug resistance predictions for 15/16 (93.7%) clinical samples were highly concordant with phenotypic DST for isoniazid, rifampicin, amikacin, and kanamycin [15/15 (100%)], ethambutol [12/15 (80%)] and moxifloxacin [14/15 (93.3%)]. These results highlighted the potential of FLASH-TB for detecting Mtb drug resistance from sputum samples.

Humans

Multimodal genomic surveillance for respiratory pathogens at four U.S. international airports: A comparison of air, wastewater, clinical, and national surveillance data.

Early detection of outbreaks and emerging pathogens is critical for public health and global biosecurity. Airports, as major international travel hubs with dense, enclosed populations, are high-risk settings for disease transmission and potential pathogen introduction. The U.S. Centers for Disease Control and Prevention, in collaboration with Ginkgo Biosecurity and the University of Wisconsin-Madison, implemented air monitoring for pathogen surveillance in congregate areas at four U.S. international airports. From October 2023 to August 2024, SARS-CoV-2 was detected by PCR in 98.3% of air samples and influenza A in 17.2%. Influenza A positivity in air samples correlated with aviation wastewater (r&#x2009;=&#x2009;0.48), traveler nasal swab positivity (r&#x2009;=&#x2009;0.73), and national clinical surveillance (r&#x2009;=&#x2009;0.86), whereas SARS-CoV-2 measurements did not correlate significantly across these modalities. Targeted amplicon sequencing of SARS-CoV-2 from air samples identified contemporaneous lineages also detected in wastewater collected from the same airports. Targeted enrichment sequencing detected 30 viral species and recovered high-quality genomes for SARS-CoV-2, influenza, bocavirus, and seasonal coronaviruses. Together, these findings demonstrate that air sampling can complement aviation wastewater surveillance at ports of entry, although performance and concordance vary by pathogen and sample type.

Journal Article

Targeted Next-Generation Sequencing in Rare Diseases.

Targeted next-generation sequencing (NGS) in rare disease focuses on genetic analysis of specific regions in genome that are linked to a rare disease. In addition to library preparation, sequencing, and data analysis, targeted NGS includes an additional step of target enrichment of selected genes and regions. It allows for more sensitive and profound sequencing, as it is a fast and cost-effective approach with less data burden and is therefore often a method of choice for identifying rare variants in known genes, especially in diagnostics of rare diseases. Several in silico tools address the pathogenicity predictions of rare variants of unknown significance (VUS) and can therefore facilitate clinical interpretation.

Rare Diseases

Innovations in Transgene Integration Analysis: A Comprehensive Review of Enrichment and Sequencing Strategies in Biotechnology.

Understanding the integration of transgene DNA (T-DNA) in transgenic crops, animals, and clinical applications is paramount for ensuring the stability and expression of inserted genes, which directly influence desired traits and therapeutic outcomes. Analyzing T-DNA integration patterns is essential for identifying potential unintended effects and evaluating the safety and environmental implications of genetically modified organisms (GMOs). This knowledge is crucial for regulatory compliance and fostering public trust in biotechnology by demonstrating transparency in genetic modifications. This review highlights recent advancements in T-DNA integration analysis, specifically focusing on targeted DNA enrichment and sequencing strategies. We examine key technologies, such as polymerase chain reaction (PCR)-based methods, hybridization capture, RNA/DNA-guided endonuclease-mediated enrichment, and high-throughput resequencing, emphasizing their contributions to enhancing precision and efficiency in transgene integration analysis. We discuss the principles, applications, and recent developments in these techniques, underscoring their critical role in advancing biotechnological products. Additionally, we address the existing challenges and future directions in the field, offering a comprehensive overview of how innovative DNA-targeted enrichment and sequencing strategies are reshaping biotechnology and genomics.

Transgenes

Characterization of the brain virome in human immunodeficiency virus infection and substance use disorder.

Viruses can infect the brain in individuals with and without HIV-infection: however, the brain virome is poorly characterized. Metabolic alterations have been identified which predispose people to substance use disorder (SUD), but whether these could be triggered by viral infection of the brain is unknown. We used a target-enrichment, deep sequencing platform and bioinformatic pipeline named "ViroFind", for the unbiased characterization of DNA and RNA viruses in brain samples obtained from the National Neuro-AIDS Tissue Consortium. We analyzed fresh frozen post-mortem prefrontal cortex from 72 individuals without known viral infection of the brain, including 16 HIV+/SUD+, 20 HIV+/SUD-, 16 HIV-/SUD+, and 20 HIV-/SUD-. The average age was 52.3 y and 62.5% were males. We identified sequences from 26 viruses belonging to 11 viral taxa. These included viruses with and without known pathogenic potential or tropism to the nervous system, with sequence coverage ranging from 0.03 to 99.73% of the viral genomes. In SUD+ people, HIV-infection was associated with a higher total number of viruses, and HIV+/SUD+ compared to HIV-/SUD+ individuals had an increased frequency of Adenovirus (68.8 vs 0%; p<0.001) and Epstein-Barr virus (EBV) (43.8 vs 6.3%; p=0.037) as well as an increase in Torque Teno virus (TTV) burden. Conversely, in HIV+ people, SUD was associated with an increase in frequency of Hepatitis C virus, (25 in HIV+/SUD+ vs 0% in HIV+/SUD-; p=0.031). Finally, HIV+/SUD- compared to HIV-/SUD- individuals had an increased frequency of EBV (50 vs 0%; p<0.001) and an increase in TTV viral burden, but a decreased Adenovirus viral burden. These data demonstrate an unexpectedly high variety in the human brain virome, identifying targets for future research into the impact of these taxa on the central nervous system. ViroFind could become a valuable tool for monitoring viral dynamics in various compartments, monitoring outbreaks, and informing vaccine development.

Male

Diagnostic and phylogenetic perspectives of the 2023 Murray Valley encephalitis virus outbreak in Australia: an observational study.

BACKGROUND: An outbreak of Murray Valley encephalitis virus (MVEV), the largest since 1974, was observed in Australia between Jan 1 and July 31, 2023. This study aims to characterise the utility of diagnostic platforms, testing algorithms, and genomic characteristics of MVEV to facilitate a comprehensive framework for MVEV testing and surveillance in the outbreak setting. METHODS: In this observational study, we assessed flavivirus diagnostics for all patients with suspected Murray Valley encephalitis in Australia from Jan 1 to July 31, 2023. We included all patients with confirmed Murray Valley encephalitis, probable Murray Valley encephalitis, or acute unspecified flavivirus infection using the Communicable Diseases Network Australia case definition. Cases were excluded if an alternative diagnosis was identified. We collected blood, serum, cerebrospinal fluid, brain tissue, urine, or a combination of these samples, as appropriate and at the discretion of the treating clinician. We conducted multimodal diagnostic testing, which included flavivirus-specific serological and nucleic acid amplification testing. Metagenomic next-generation sequencing, including next-generation deep sequencing, target-enrichment, and targeted amplification, was conducted on human and representative mosquito-derived samples obtained from established mosquito population surveillance programmes for phylogenetic analysis. FINDINGS: 27 patients with encephalitis were assessed for MVEV between Jan 1, 2023, and July 31, 2023, 23 (85%) of whom fulfilled national case definitions for confirmed Murray Valley encephalitis. Patient ages ranged from 6 weeks to 83 years (median 62&#xb7;0 years [IQR 31&#xb7;0-67&#xb7;5]) and patients were mostly male (21 [78%] male patients and six [22%] female patients). Incidence varied widely by geographical region and was highest in the Northern Territory (32&#xb7;0 per 1&#x2009;000&#x2009;000 population). Diagnostic specimen collection generally occurred promptly (median 6&#xb7;0 days [IQR 4&#xb7;0-14&#xb7;5] from symptom onset to diagnostic specimen collection). In seven patients, case assignation relied on convalescent serum samples to assess for seroconversion or an appropriate rise in antibody titre (to four times the initial value or greater), or both. MVEV-specific IgM was detectable in serum samples of 17 (81%) of 21 patients tested by day 7 and MVEV IgG or total antibody (TAb) were detected in 18 (100%) of 18 patients tested by day 30. MVEV-specific IgM (or TAb) and MVEV RNA were detected in cerebrospinal fluid collected within 14 days of symptom onset in nine (39%) of 23 patients and seven (28%) of 25 patients, respectively. Phylogenetic analysis revealed two circulating MVEV genotypes, G1A and G2, in mosquitoes and humans in 2023. In southeast Australia, only G1A was detected and probably introduced from enzootic foci in northern Australia. INTERPRETATION: This study provides a comprehensive overview of the diagnostic workflows and phylogenetic evaluations used during the 2023 MVEV outbreak in Australia, emphasising the importance of a multimodal approach for accurate and timely confirmation of flavivirus infection. Further One Health surveillance for MVEV and other zoonotic flaviviruses is key, given potential expanded ecological niches in the context of episodic climatic events. FUNDING: None.

Humans

Phylogenomics and evolution of the Lauraceae based on targeted capture data.

The family Lauraceae, a hyper-diverse magnoliid family comprising approximately 63 genera and over 3,000 species, plays a key ecological role in tropical and subtropical forests. Yet deep relationships among its nine tribes remain unresolved, likely due to limited sampling and complex evolutionary processes such as incomplete lineage sorting (ILS) and gene flow. To address these challenges, we generated datasets of 255 single-copy nuclear genes and chloroplast genomes using a newly designed Lauraceae-specific probe set, achieving the most comprehensive genus-level sampling (84%) to date. Phylogenomic analyses reconstructed a robust nuclear tree, which resolved the Neocinnamomeae as sister to the Caryodaphnopsideae and revealed pronounced gene tree conflict and pervasive cytonuclear discordance. To investigate the evolutionary processes underlying these patterns, comprehensive analyses were conducted. The results indicate that conflicting nuclear gene trees reflect the combined effects of ILS, gene tree estimation error, and gene flow, with ILS dominating across the core Lauraceae, whereas cytonuclear discordance is primarily driven by extensive gene flow. Diversification analyses further indicate that episodes of rapid lineage accumulation coincide with major gene flow events, suggesting a potential role of gene flow in the diversification of Lauraceae. Overall, this study provides a robust nuclear phylogenomic framework for Lauraceae and demonstrates that gene flow had profound effects on its evolutionary history, shedding light on the contribution of gene flow to the diversification of hyper-diverse tropical plant lineages.

Cytonuclear discordance

Genomic hallmarks of depot medroxyprogesterone acetate-associated meningiomas.

BACKGROUND: Population-based studies have linked progestin exposure to increased meningioma risk. However, the molecular basis of meningiomas associated with depot medroxyprogesterone acetate (DMPA)-a common injectable contraceptive-remains undefined. METHODS: We performed an integrated clinicopathologic and genomic analysis of meningiomas from 10 women with long-term DMPA exposure. Tumors underwent histopathological analysis, targeted sequencing, and DNA methylation profiling. Data were integrated with reference cohorts (Baylor and Heidelberg) and analyzed through classifier assignment, consensus clustering, copy number analysis, differential methylation testing, and dimensionality reduction. RESULTS: Depot medroxyprogesterone acetate-associated meningiomas were all newly diagnosed, World Health Organization grade 1 tumors with a predilection for the anterior and central skull base (n&#x2009;=&#x2009;6). Nine patients harbored multiple meningiomas. Four experienced regression of untreated meningiomas following DMPA cessation, while 5 demonstrated stabilization. Histopathology demonstrated relative overrepresentation of metaplastic morphology, an uncommon meningioma subtype. All DMPA-associated meningiomas mapped to benign molecular groups, and most exhibited low copy number alteration burden. Targeted sequencing revealed enrichment for TRAF7 mutations (n&#x2009;=&#x2009;5), with no NF2 mutations detected. Eight tumors shared consensus cluster identity, with cohesive grouping on principal component analysis and t-distributed stochastic neighbor embedding. No differential methylation was identified at the progesterone receptor locus. CONCLUSIONS: Depot medroxyprogesterone acetate-associated meningiomas represent a recognizable phenotype within the broader NF2-wildtype/TRAF7-enriched spectrum of benign meningiomas, characterized by chromosomal stability, a shared methylation profile, tumor multiplicity, and regression or stabilization following DMPA cessation. While derived from a small single-institution cohort, these findings provide a molecular framework for understanding progestin-associated meningioma biology, reinterpreting epidemiologic literature, and informing population-level risk stratification.

Humans

Developing and Benchmarking One Health Genomic Surveillance Tools for Influenza A Virus in Wastewater.

Influenza A viruses (IAV) remain a persistent One Health threat, and whole-genome sequencing from wastewater offers a promising surveillance tool. However, IAV is at low abundance in wastewater, making it difficult to sequence. We benchmarked four targeted enrichment methods suited for whole-genome sequencing including custom and off-the-shelf amplicon and probe-based methods. Our custom HA tiled-amplicon panel was sensitive, fast, and cost-effective, making it suitable for monitoring low-abundance seasonal variants of known subtypes. However, its reliance on conserved and intact primer-binding sites limited primer design to fewer subtypes. A previously published universal amplicon method targeted all IAV subtypes, but it performed poorly in wastewater due to its reliance on intact genome segments. Probe-capture methods were resilient to RNA degradation and mismatches, potentially enabling broader surveillance and detection of emerging strains. However, probes were costly, labor-intensive, and less sensitive than tiled-amplicon. When testing compatibility of sequencing methods with upstream virus concentration and extraction methods, ultrafiltration-based virus concentration outperformed large-volume direct extraction with all four sequencing methods. This set of benchmarking comparisons and custom panels provides needed information for the translation of IAV genomic sequencing into a routine component of wastewater surveillance.

Journal Article

Transcript-guided targeted cell enrichment for scalable single-nucleus RNA sequencing.

Large-scale single-cell atlases have revealed many aging- and disease-associated cell types, yet these populations are often underrepresented in heterogeneous tissues, limiting detailed molecular analyses. To address this, we developed EnrichSci-a scalable, microfluidics-free platform that combines hybridization chain reaction RNA fluorescence in situ hybridization (FISH) with combinatorial indexing to profile single-nucleus transcriptomes of target cell types with full gene-body coverage. Applied to oligodendrocytes in the aging mouse brain, EnrichSci uncovered aging-associated molecular dynamics across distinct oligodendrocyte subtypes, revealing both shared and subtype-specific gene expression changes. Additionally, we identified aging-associated exon-level signatures missed by conventional gene-level analyses, highlighting post-transcriptional regulation as a critical dimension of cell-state dynamics in aging. By coupling transcript-guided enrichment with a scalable sequencing workflow, EnrichSci provides a versatile approach to decode dynamic regulatory landscapes in diverse cell types from complex tissues.

Animals

Portable metagenomics for preventive surveillance and outbreak control in livestock and poultry: Pathogen detection, resistome profiling, and antimicrobial stewardship.

Conventional diagnostics for livestock and poultry outbreaks commonly rely on culture or targeted PCR panels, which may be too slow or too narrow to guide early control decisions. Portable metagenomics, particularly real-time nanopore sequencing, offers a route to broad pathogen detection, antimicrobial-resistance gene profiling, and outbreak investigation within an integrated workflow. This implementation-focused review evaluates how near-point-of-care metagenomics may support preventive veterinary medicine through earlier detection, surveillance, cohorting, biosecurity decisions, and antimicrobial stewardship. We synthesize sample-to-answer workflows for enteric and respiratory disease in food-producing animals, including sampling, nucleic-acid extraction, host depletion or target enrichment, library preparation, sequencing, bioinformatics, quality control, and interpretation. Applications in calf diarrhea, bovine respiratory disease, poultry outbreaks, mastitis, and resistome monitoring are considered alongside the central limitation that detection alone does not establish causation. Pathogen and resistance-gene signals must therefore be interpreted with clinical signs, lesions, epidemiology, controls, and confirmatory testing. We also propose a minimum reporting checklist, intended as a practical framework rather than a validated consensus standard. Portable metagenomics is not a replacement for conventional diagnostics, but appropriately validated workflows can reduce uncertainty during time-sensitive outbreaks and support more judicious antimicrobial use.

Animals

Identification and full genome sequencing of previously unknown sandfly-borne phleboviruses using a newly established capture-based next-generation sequencing approach.

Sandfly-borne phleboviruses cause febrile illness and neuroinvasive disease in humans. While infections are reported in the Mediterranean region, the discovery of previously unknown phleboviruses in sandflies from Kenya suggests a wider geographic distribution. Detection and characterization of novel phleboviruses are often hindered by low-quality and low-viral-load samples. We developed a capture-based target enrichment next-generation sequencing approach that showed a 99%-100% fold enrichment of viral genomes from primary material and provides a robust tool for generating complete genomes of both known and previously unknown viruses. From a collection of 15,652 sandflies in Kenya, we recovered seven complete coding sequences of Embossos, Bogoria, and Kiborgoch viruses, and of two previously unknown phleboviruses, which were named Sosoik and Shable viruses. Sosoik virus shared 83% amino acid identity in its RdRp gene with that of Bogoria virus, while Shable virus shared ca. 88% amino acid identity with viruses of the Salehabad serocomplex. Additionally, a reassortant of Shable virus was detected that possessed an M segment from an undescribed Ponticelli-like virus. DNA barcoding of blood-fed sandflies revealed several potentially novel Sergentomyia species and evidence of host-feeding on humans, livestock, and reptiles, suggesting possibilities for zoonotic transmission. Overall, our findings increase the known genetic diversity of Old World sandfly-borne phlebovirus species from 18 to 25 (by 38.9%), including the detection of viruses from all pathogenic sandfly-borne phlebovirus serocomplexes in East Africa, opening new horizons in disease ecology research.IMPORTANCEKnowledge of the genetic diversity of circulating pathogens is crucial for providing appropriate diagnostics and disease management. This study established a novel capture-based target enrichment next-generation sequencing approach that enabled the near-complete viral genome recovery from primary samples, while native NGS yielded negative or poor-quality results. In addition to the five recently discovered sandfly-borne phleboviruses in Kenya, two previously unknown phleboviruses were detected in sandflies from the same region. The viruses were detected in several sandfly species, which showed diverse host-feeding behaviors, including mixed feeding on humans and chickens. The study significantly advances the understanding of sandfly-borne phleboviruses by uncovering their broader geographic distribution and genetic diversity, particularly in East Africa, highlighting the importance of expanding surveillance efforts beyond traditionally studied regions.

Phlebovirus

Mannheimia haemolytica strain-level diversity in cattle populations.

High-resolution genomic characterization is essential for understanding diversity, pathogenicity, and transmission dynamics of bacterial pathogens. Mannheimia haemolytica (Mh) is the most consequential bacterial agent associated with bovine respiratory disease (BRD) in cattle, as a leading cause of morbidity, mortality, and antimicrobial use. Historically, BRD pathogens, including Mh, have been studied using culture or PCR approaches that provided limited ability to characterize fine-scale genomic variation across communities. Here, we evaluated target-enriched (TE) shotgun sequencing, a culture-independent method capable of strain-level resolution within metagenomic data, for detecting and characterizing Mh in comparison with qPCR and 16S rRNA gene sequencing. Nasal swabs (10 individual and 2 composited DNA samples per pen) and environmental samples (three ropes hung on pen rails and three water bowl swabs per pen) were collected from four pens in each of five distinct cattle populations. DNA was extracted for TE sequencing to identify Mh at both species and genomic sequence variant (GSV) levels, and to characterize antimicrobial resistance genes across the bacterial communities. qPCR was performed to quantify Mh genome copies, and 16S rRNA gene sequencing was used to assess the broader respiratory microbiome. TE sequencing identified Mh in 100% of TE-tested samples and classified multiple GSVs in all but 3 of 121 samples. GSV profiles clustered within housing groups and varied across cattle populations, indicating structured strain-level diversity. In contrast, Mannheimia spp. were detected in only 47.7% of samples by 16S rRNA sequencing. These findings demonstrate that TE sequencing enables sensitive, strain-level characterization of Mh in cattle and environmental samples and reveals substantial within-population genomic diversity not captured by conventional approaches.IMPORTANCETarget-enriched shotgun sequencing enabled sensitive, strain-level detection of Mannheimia haemolytica (Mh), revealing multiple co-circulating genomic sequence variants (GSVs) within and among cattle groups. This demonstrates greater genetic variability of Mh populations in beef cattle than has been previously recognized. The clustering of GSVs within housing groups, together with the overlap between respiratory and environmental samples, is consistent with the hypothesis that contagious transmission contributes to Mh ecology. These results highlight the potential utility of composite nasal swab and environmental samples for future studies evaluating relationships between Mh genomic variation and disease risk.

Animals

Evaluation of one-step amplicon-based targeted enrichment for SARS-CoV-2 whole-genome sequencing using the Midnight amplicon scheme.

Genomic surveillance proved invaluable during the COVID-19 pandemic for tracking SARS-CoV-2 variants and guiding outbreak responses, underscoring the ongoing need to reduce whole-genome sequencing (WGS) costs and improve workflow efficiency to ensure accessibility in resource limited settings. Here, we evaluated a one-step reverse transcription polymerase chain reaction (RT-PCR) approach using the Midnight V2 primer scheme for targeted amplification of the SARS-CoV-2 genome, assessed its compatibility with Illumina sequencing, and compared its performance to a well-established two-step method. Initially, we determined optimal RT-PCR reaction conditions using the Midnight V2 primer panel for the one-step RT-PCR kit and scaled reaction volumes for both RT-PCR and library preparation. Clinical specimens (n&#x202f;=&#x202f;53) that had undergone routine WGS for surveillance purposes using the established two-step RT-PCR method were compared using the one-step RT-PCR assay. For samples with genome completeness greater than 70%, both methods gave comparable results with similar sequence coverage and 100% concordance for lineage assignment. Further investigation revealed a higher percentage of reads aligning to the SARS-CoV-2 genome with a greater depth of coverage using the one-step method compared to the two-step method. Finally, analysis of scaled one-step and library reaction volumes revealed significant cost savings for samples undergoing WGS. Overall, the results presented here verify the accuracy and reproducibility of one-step targeted amplification and offer an efficient and cost-effective workflow for routine SARS-CoV-2 genomic surveillance.

Humans

Hybridization capture increases on-target nanopore sequencing of plant RNA tobamovirus- derived cDNA libraries.

High-throughput sequencing (HTS) can support plant virus surveillance, but host nucleic acids often reduce on-target read recovery. We evaluated a targeted hybridization-capture workflow in which barcoded double-stranded cDNA (ds-cDNA) libraries generated from plant RNA extracts spiked with lyophilized tobamovirus-positive controls were enriched before Oxford Nanopore sequencing. Biotinylated probes targeted conserved regions of cucumber green mottle mosaic virus (CGMMV), species Tobamovirus viridimaculae; pepper mild mottle virus (PMMoV), species Tobamovirus capsici; and tobacco mosaic virus (TMV), species Tobamovirus tabaci. Across four pairs per virus, relative target-read abundance increased after capture from 0.76 &#xb1; 0.33% to 37.62 &#xb1; 15.72% for CGMMV, 8.16 &#xb1; 3.86% to 24.68 &#xb1; 12.34% for PMMoV, and 15.62 &#xb1; 10.40% to 36.83 &#xb1; 30.33% for TMV. Exact two-sided Wilcoxon signed-rank tests yielded P = 0.125 for each virus; with four nonzero differences in a common direction, this was the minimum attainable two-sided P value. Genome-coverage breadth was maintained. Retrospective duplex qPCR supported an increased virus-to-18S ratio for CGMMV, showed a variable PMMoV response, and showed a decreased virus-to-18S ratio for TMV because the 18S signal shifted earlier by as much as or more than the TMV signal. The findings provide proof-of-concept evidence for target-dependent library enrichment but do not establish analytical sensitivity, diagnostic performance, or field validity. Validation with naturally infected, low-titer, and mixed-infection samples and comparison with simpler targeted workflows are required.

biosecurity