Background Species-level genetic characterization of complex bacterial communities has important clinical applications in both diagnosis and treatment. Amplicon sequencing of the 16S ribosomal RNA (rRNA) gene has proven to be a powerful strategy for the taxonomic classification of bacteria. This study aims to improve the method for full-length 16S rRNA gene analysis using the nanopore long-read sequencer MinION™. We compared it to the conventional short-read sequencing method in both a mock bacterial community and human fecal samples. Results We modified our existing protocol for full-length 16S rRNA gene amplicon sequencing by MinION™. A new strategy for library construction with an optimized primer set overcame PCR-associated bias and enabled taxonomic classification across a broad range of bacterial species. We compared the performance of full-length and short-read 16S rRNA gene amplicon sequencing for the characterization of human gut microbiota with a complex bacterial composition. The relative abundance of dominant bacterial genera was highly similar between full-length and short-read sequencing. At the species level, MinION™ long-read sequencing had better resolution for discriminating between members of particular taxa such as Bifidobacterium, allowing an accurate representation of the sample bacterial composition. Conclusions Our present microbiome study, comparing the discriminatory power of full-length and short-read sequencing, clearly illustrated the analytical advantage of sequencing the full-length 16S rRNA gene.

Highlights d Autoimmune SNPs are enriched in naive Treg cell-specific CpG hypomethylated regions d Treg-specific CpG hypomethylation is associated with Treg cell super-enhancers d Naive Treg cell-specific epigenetics controls activated Treg cell function

33Species-level genetic characterization of complex bacterial communities has important 34 clinical applications. In the present study, we assessed the performance of full-length 35 16S rRNA gene analysis of human gut microbiota using the nanopore long-read 36 sequencer MinION™. A new strategy for library construction with an optimized primer 37 set overcame PCR-associated bias and produced accurate taxonomic classifications of a 38 broad range of bacterial species. Our present microbiome study, comparing the 39 discriminatory power of full-length and short-read sequencing, clearly illustrated the 40 analytical advantage of sequencing the full-length 16S rRNA gene, which provided 41 higher species-level resolution and accuracy. 42 43 Keywords: 44 16S rRNA, gut microbiota, metagenome, MinION™, nanopore sequencing 45 46 4 Background 47 Recent advances in DNA sequencing technology have had a revolutionary impact on 48 clinical microbiology [1]. Next-generation sequencing (NGS) technology enables 49 parallel sequencing of DNA on a massive scale to generate vast quantities of accurate 50 data. NGS platforms are now increasingly used in the field of clinical research [2]. 51 Metagenomic sequencing offers numerous advantages over traditional culture-based 52 techniques that have long been the standard test for detecting pathogenic bacteria. This 53 method is particularly useful for characterizing uncultivable bacteria and novel 54 pathogens [3].55 Among the metagenomic sequencing strategies, amplicon sequencing of the 16S 56 ribosomal RNA (rRNA) gene has proven to be a reliable and efficient option for 57 taxonomic classification [4, 5]. The bacterial 16S rRNA gene contains nine variable 58 regions (V1 to V9) that are separated by highly conserved sequences across different 59 taxa. For bacterial identification, the 16S rRNA gene is first amplified by polymerase 60 chain reaction (PCR) with primers annealing to conserved regions and then sequenced.61 The sequencing data are subjected to bioinformatic analysis in which the variable 62 regions are used to discriminate between bacterial taxa [6]. 63 Since the conventional parallel-type short-read sequencer cannot yield reads covering 64 the full length of the 16S rRNA gene [7], several regions of it have been targeted for 65 sequencing, which often causes ambiguity in taxonomic classification [8]. New 66 sequencing platforms have overcome these technical restrictions, particularly those 67 affecting read length. A prime example is the MinION™ sequencer from Oxford 68Nanopore Technologies, which is capable of producing long sequences with no 69 theoretical read length limit [9][10][11]. MinION™ sequencing targets the entire 16S rRNA 70 gene, allowing the identification of bacteria with more accuracy and sensitivity [12, 13]. 71Furthermore, MinION™ produces sequencing data in real time, which reduces 72 turnaround time for data processing [14, 15]. 73 5Given these features of MinION™ sequencing, we had previously conducted full-length 74 16S amplicon sequencing analyse...

Elucidation of natural selection signatures and relationships with phenotype spectra is important to understand adaptive evolution of modern humans. Here, we conducted a genome-wide scan of selection signatures of the Japanese population by estimating locus-specific time to the most recent common ancestor using the ascertained sequentially Markovian coalescent (ASMC), from the biobank-based large-scale genome-wide association study data of 170,882 subjects. We identified 29 genetic loci with selection signatures satisfying the genome-wide significance. The signatures were most evident at the alcohol dehydrogenase (ADH) gene cluster locus at 4q23 (PASMC = 2.2 × 10−36), followed by relatively strong selection at the FAM96A (15q22), MYOF (10q23), 13q21, GRIA2 (4q32), and ASAP2 (2p25) loci (PASMC < 1.0 × 10−10). The additional analysis interrogating extended haplotypes (integrated haplotype score) showed robust concordance of the detected signatures, contributing to fine-mapping of the genes, and provided allelic directional insights into selection pressure (e.g., positive selection for ADH1B-Arg48His and HLA-DPB1*04:01). The phenome-wide selection enrichment analysis with the trait-associated variants identified a variety of the modern human phenotypes involved in the adaptation of Japanese. We observed population-specific evidence of enrichment with the alcohol-related phenotypes, anthropometric and biochemical clinical measurements, and immune-related diseases, differently from the findings in Europeans using the UK Biobank resource. Our study demonstrated population-specific features of the selection signatures in Japanese, highlighting a value of the natural selection study using the nation-wide biobank-scale genome and phenotype data.

Myasthenia gravis (MG) is a neurological disease caused by autoantibodies against neuromuscular-associated proteins. While MG frequently develops in thymoma patients, the etiologic factors for MG are not well understood. Here, by constructing a comprehensive atlas of thymoma using bulk and single-cell RNA-sequencing, we identify ectopic expression of neuromuscular molecules in MG-type thymoma. These molecules are found within a distinct subpopulation of medullary thymic epithelial cells (mTECs), which we name neuromuscular mTECs (nmTECs). MG-thymoma also exhibits microenvironments dedicated to autoantibody production, including ectopic germinal center formation, T follicular helper cell accumulation, and type 2 conventional dendritic cell migration. Cell–cell interaction analysis also predicts the interaction between nmTECs and T/B cells via CXCL12-CXCR4. The enrichment of nmTECs presenting neuromuscular molecules within MG-thymoma is further confirmed immunohistochemically and by cellular composition estimation from the MG-thymoma transcriptome. Altogether, this study suggests that nmTECs have a significant function in MG pathogenesis via ectopic expression of neuromuscular molecules.

Regulatory T (Treg) cells, expressing CD25 (interleukin-2 receptor α chain) and Foxp3 transcription factor, maintain immunological self-tolerance and suppress various immune responses. Here we report a feature of skin Treg cells expanded by ultraviolet B (UVB) exposure. We found that skin Treg cells possessing a healing function are expanded by UVB exposure with the expression of an endogenous opioid precursor, proenkephalin (PENK). Upon UVB exposure, skin Treg cells were expanded with a unique TCR repertoire. Also, they highly expressed a distinctive set of genes enriched in “wound healing involved in inflammatory responses” and the “neuropeptide signaling pathway,” as indicated by the high expression of Penk. We found that not only was PENK expression at the protein level detected in the UVB-expanded skin Treg (UVB-skin Treg) cells, but that a PENK-derived neuropeptide, methionine enkephalin (Met-ENK), from Treg cells promoted the outgrowth of epidermal keratinocytes in an ex vivo skin explant assay. Notably, UVB-skin Treg cells also promoted wound healing in an in vivo wound closure assay. In addition, UVB-skin Treg cells produced amphiregulin (AREG), which plays a key role in Treg-mediated tissue repair. Identification of a unique function of PENK+ UVB-skin Treg cells provides a mechanism for maintaining skin homeostasis.

Foxp3-expressing CD25+CD4+ regulatory T cells (Tregs) are abundant in tumor tissues. Here, hypothesizing that tumor Tregs would clonally expand after they are activated by tumor-associated antigens to suppress antitumor immune responses, we performed single-cell analysis on tumor Tregs to characterize them by T cell receptor clonotype and gene-expression profiles. We found that multiclonal Tregs present in tumor tissues predominantly expressed the chemokine receptor CCR8. In mice and humans, CCR8+ Tregs constituted 30 to 80% of tumor Tregs in various cancers and less than 10% of Tregs in other tissues, whereas most tumor-infiltrating conventional T cells (Tconvs) were CCR8–. CCR8+ tumor Tregs were highly differentiated and functionally stable. Administration of cell-depleting anti-CCR8 monoclonal antibodies (mAbs) indeed selectively eliminated multiclonal tumor Tregs, leading to cure of established tumors in mice. The treatment resulted in the expansion of CD8+ effector Tconvs, including tumor antigen-specific ones, that were more activated and less exhausted than those induced by PD-1 immune checkpoint blockade. Anti-CCR8 mAb treatment also evoked strong secondary immune responses against the same tumor cell line inoculated several months after tumor eradication, indicating that elimination of tumor-reactive multiclonal Tregs was sufficient to induce memory-type tumor-specific effector Tconvs. Despite induction of such potent tumor immunity, anti-CCR8 mAb treatment elicited minimal autoimmunity in mice, contrasting with systemic Treg depletion, which eradicated tumors but induced severe autoimmune disease. Thus, specific removal of clonally expanding Tregs in tumor tissues for a limited period by cell-depleting anti-CCR8 mAb treatment can generate potent tumor immunity with long-lasting memory and without deleterious autoimmunity.

The possibility that RNA transcripts from clinical samples contain plenty of virus RNAs has not been pursued actively so far. We here developed a new tool for analyzing virus-transcribed mRNAs, not virus copy numbers, in the data of bulk and single-cell RNA-sequencing of human cells. Our pipeline, named VIRTUS (VIRal Transcript Usage Sensor), was able to detect 762 viruses including herpesviruses, retroviruses, and even SARS-CoV-2 (COVID-19), and quantify their transcripts in the sequence data. This tool thus enabled simultaneously detecting infected cells, the composition of multiple viruses within the cell, and the endogenous host gene expression profile of the cell. This bioinformatics method would be instrumental in addressing the possible effects of covertly infecting viruses on certain diseases and developing new treatments to target such viruses. Availability VIRTUS is implemented using Common Workflow Language and Docker under a CC-NC license. VIRTUS is freely available at https://github.com/yyoshiaki/VIRTUS. Supplementary information Supplementary data are available at Bioinformatics online.