Intestinal virome changes precede autoimmunity in type I diabetes-susceptible children

Gut microbiome in the first 1000 days and risk for childhood food allergy

OBJECTIVE

To summarize recent data on the association between gut microbiome composition and food allergy (FA) in early childhood and highlight potential host-microbiome interactions that reinforce or abrogate oral tolerance.

DATA SOURCES

PubMed search of English-language articles related to FA, other atopic disease, and the gut microbiome in pregnancy and early childhood.

STUDY SELECTIONS

Human studies published after 2015 assessing the relationship between the gut bacteriome and virome in the first 2 years of life and FA or food sensitization development in early childhood were prioritized. Additional human studies conducted on the prenatal gut microbiome or other atopic diseases and preclinical studies are also discussed.

RESULTS

Children who developed FA harbored lower abundances of Bifidobacterium and Clostridia species and had a less mature microbiome during infancy. The early bacterial microbiome protects against FA through production of anti-inflammatory metabolites and induction of T regulatory cells and may also affect FA risk through a role in trained immunity. Infant enteric phage communities are related to childhood asthma development, though no data are available for FA. Maternal gut microbiome during pregnancy is associated with childhood FA risk, potentially through transplacental delivery of maternal bacterial metabolites, though human studies are lacking.

CONCLUSION

The maternal and infant microbiomes throughout the first 1000 days of life influence FA risk through a number of proposed mechanisms. Further large, longitudinal cohort studies using taxonomic, functional, and metabolomic analysis of the bacterial and viral microbiomes are needed to provide further insight on the host-microbe interactions underlying FA pathogenesis in childhood.

A Review of Stage 0 Biomarkers in Type 1 Diabetes: The Holy Grail of Early Detection and Prevention?

Type 1 diabetes mellitus (T1D) is an incurable autoimmune disease characterized by the destruction of pancreatic islet cells, resulting in lifelong dependency on insulin treatment. There is an abundance of review articles addressing the prediction of T1D; however, most focus on the presymptomatic phases, specifically stages 1 and 2. These stages occur after seroconversion, where therapeutic interventions primarily aim to delay the onset of T1D rather than prevent it. This raises a critical question: what happens before stage 1 in individuals who will eventually develop T1D? Is there a "stage 0" of the disease, and if so, how can we detect it to increase our chances of truly preventing T1D? In pursuit of answers to these questions, this narrative review aimed to highlight recent research in the field of early detection and prediction of T1D, specifically focusing on biomarkers that can predict T1D before the onset of islet autoimmunity. Here, we have compiled influential research from the fields of epigenetics, omics, and microbiota. These studies have identified candidate biomarkers capable of predicting seroconversion from very early stages to several months prior, suggesting that the prophylactic window begins at birth. As the therapeutic landscape evolves from treatment to delay, and ideally from delay to prevention, it is crucial to both identify and validate such "stage 0" biomarkers predictive of islet autoimmunity. In the era of precision medicine, this knowledge will enable early intervention with the potential for delaying, modifying, or completely preventing autoimmunity and T1D in at-risk children.

Rheumatoid arthritis patients harbour aberrant enteric bacteriophages with autoimmunity-provoking potential: a paired sibling study

OBJECTIVES

Viruses have been considered as important participants in the development of rheumatoid arthritis (RA). However, the profile of enteric virome and its role in RA remains elusive. This study aimed to investigate the atlas and involvement of virome in RA pathogenesis.

METHODS

Faecal samples from 30 pairs of RA and healthy siblings that minimise genetic interferences were collected for metagenomic sequencing. The α and β diversity of the virome and the virome-bacteriome interaction were analysed. The differential bacteriophages were identified, and their correlations with clinical and immunological features of RA were analysed. The potential involvement of these differential bacteriophages in RA pathogenesis was further investigated by auxiliary metabolic gene annotation and molecular mimicry study. The responses of CD4+ T cells and B cells to the mimotopes derived from the differential bacteriophages were systemically studied.

RESULTS

The composition of the enteric bacteriophageome was distorted in RA. The differentially presented bacteriophages correlated with the immunological features of RA, including anti-CCP autoantibody and HLA-DR shared epitope. Intriguingly, the glycerolipid and purine metabolic genes were highly active in the bacteriophages from RA. Moreover, peptides of RA-enriched phages, in particular Prevotella phage and Oscillibacter phage could provoke the autoimmune responses in CD4+ T cells and plasma cells via molecular mimicry of the disease-associated autoantigen epitopes, especially those of Bip.

CONCLUSIONS

This study provides new insights into enteric bacteriophageome in RA development. In particular, the aberrant bacteriophages demonstrated autoimmunity-provoking potential that would promote the occurrence of the disease.

Phylogeny and disease associations of a widespread and ancient intestinal bacteriophage lineage

Viruses are core components of the human microbiome, impacting health through interactions with gut bacteria and the immune system. Most human microbiome viruses are bacteriophages, which exclusively infect bacteria. Until recently, most gut virome studies focused on low taxonomic resolution (e.g., viral operational taxonomic units), hampering population-level analyses. We previously identified an expansive and widespread bacteriophage lineage in inhabitants of Amsterdam, the Netherlands. Here, we study their biodiversity and evolution in various human populations. Based on a phylogeny using sequences from six viral genome databases, we propose the Candidatus order Heliusvirales. We identify heliusviruses in 82% of 5441 individuals across 39 studies, and in nine metagenomes from humans that lived in Europe and North America between 1000 and 5000 years ago. We show that a large lineage started to diversify when Homo sapiens first appeared some 300,000 years ago. Ancient peoples and modern hunter-gatherers have distinct Ca. Heliusvirales populations with lower richness than modern urbanized people. Urbanized people suffering from type 1 and type 2 diabetes, as well as inflammatory bowel disease, have higher Ca. Heliusvirales richness than healthy controls. We thus conclude that these ancient core members of the human gut virome have thrived with increasingly westernized lifestyles.

Exploring the virome: An integral part of human health and disease

The human microbiome is a complex network of microorganisms that includes viruses, bacteria, and fungi. The gut virome is an essential component of the immune system, which is responsible for regulating the growth and responses of the host's immune system. The virome maintains a crucial role in the development of numerous diseases, including inflammatory bowel disease (IBD), Crohn's disease, and neurodegenerative disorders. The human virome has emerged as a promising biomarker and therapeutic target. This comprehensive review summarizes the present understanding of the virome and its implications in matters of health and disease, with a focus on the Human Microbiome Project.

Gut virome and diabetes: discovering links, exploring therapies

This review offers a comprehensive analysis of the intricate relationship between the gut virome and diabetes, elucidating the mechanisms by which the virome engages with both human cells and the intestinal bacteriome. By examining a decade of scientific literature, we provide a detailed account of the distinct viral variations observed in type 1 diabetes (T1D) and type 2 diabetes (T2D). Our synthesis reveals that the gut virome significantly influences the development of both diabetes types through its interactions, which indirectly modulate immune and inflammatory responses. In T1D, the focus is on eukaryotic viruses that stimulate the host's immune system, whereas T2D is characterized by a broader spectrum of altered phage diversities. Promisingly, in vitro and animal studies suggest fecal virome transplantation as a potential therapeutic strategy to alleviate symptoms of T2D and obesity. This study pioneers a holistic overview of the gut virome's role in T1D and T2D, its interplay with host immunity, and the innovative potential of fecal transplantation therapy in clinical diabetes management.

Molecular characterization of plasma virome of hepatocellular carcinoma (HCC) patients

Hepatocellular carcinoma (HCC) stands as the most common cancer type, arising from various causes, and responsible for a substantial number of cancer-related fatalities. Recent advancements in viral metagenomics have empowered scientists to delve into the intricate diversity of the virosphere, viral evolution, interactions between viruses and their hosts, and the identification of viral causes behind disease outbreaks, the development of specific symptoms, and their potential role in altering the host's physiology. The present study had the objective of "Molecular Characterization of HBV, HCV, anelloviruses, CMV, SENV-D, SENV-H, HEV, and HPV viruses among individuals suffering from HCC." A total of 381 HCC patients contributed 10 cc of blood each for this study. The research encompassed the assessment of tumor markers, followed by molecular characterization of HBV, HCV, Anelloviruses (TTV, TTMV, and TTMDV), SENV-H and SENV-D viruses, HEV, CMV, and HPV, as well as histopathological examinations. The outcomes of this study revealed that majority of the HCC patients 72.4% (276/381) were male as compared to females. HCV infection, at 76.4% (291 out of 381), exhibited a significant association (p < 0.05) with HCC. Most patients displayed singular lesions in the liver, with Child Pugh Score Type B being the predominant finding in 45.2% of cases. Plasma virome analysis indicated the prevalence of TTMDV (75%), followed by TTMV (70%) and TTV (42.1%) among anelloviruses in HCC patients. Similarly, SENV-H (52%) was followed by SENV-D (20%), with co-infections at 15%. The presence of CMV and HEV among the HCC patients was recorded 5% each however 3.5% of the patients showed the presence of HPV. In conclusion, this study underscores that HCC patients serve as reservoirs for various pathogenic and non-pathogenic viruses, potentially contributing to the development, progression, and severity of the disease.

Characterization of the gut bacterial and viral microbiota in latent autoimmune diabetes in adults

Latent autoimmune diabetes in adults (LADA) is a heterogeneous disease characterized by autoantibodies against insulin producing pancreatic beta cells and initial lack of need for insulin treatment. The aim of the present study was to investigate if individuals with LADA have an altered gut microbiota relative to non-diabetic control subjects, individuals with type 1 diabetes (T1D), and individuals with type 2 diabetes (T2D). Bacterial community profiling was performed with primers targeting the variable region 4 of the 16S rRNA gene and sequenced. Amplicon sequence variants (ASVs) were generated with DADA2 and annotated to the SILVA database. The gut virome was sequenced, using a viral particle enrichment and metagenomics approach, assembled, and quantified to describe the composition of the viral community. Comparison of the bacterial alpha- and beta-diversity measures revealed that the gut bacteriome of individuals with LADA resembled that of individuals with T2D. Yet, specific genera were found to differ in abundance in individuals with LADA compared with T1D and T2D, indicating that LADA has unique taxonomical features. The virome composition reflected the stability of the most dominant order Caudovirales and the families Siphoviridae, Podoviridae, and Inoviridae, and the dominant family Microviridae. Further studies are needed to confirm these findings.

Bifidobacterium longum modifies a nutritional intervention for stunting in Zimbabwean infants

Child stunting is an indicator of chronic undernutrition and reduced human capital. However, it remains a poorly understood public health problem. Small-quantity lipid-based nutrient supplements (SQ-LNS) have been widely tested to reduce stunting, but have modest effects. The infant intestinal microbiome may contribute to stunting, and is partly shaped by mother and infant histo-blood group antigens (HBGA). We investigated whether mother-infant fucosyltransferase status, which governs HBGA, and the infant gut microbiome modified the impact of SQ-LNS on stunting at age 18 months among Zimbabwean infants in the SHINE Trial ( NCT01824940 ). We found that mother-infant fucosyltransferase discordance and Bifidobacterium longum reduced SQ-LNS efficacy. Infant age-related microbiome shifts in B. longum subspecies dominance from infantis , a proficient human milk oligosaccharide utilizer, to suis or longum , proficient plant-polysaccharide utilizers, were partly influenced by discordance in mother-infant FUT2+/FUT3- phenotype, suggesting that a "younger" microbiome at initiation of SQ-LNS reduces its benefits on stunting.

Discovering and exploring the hidden diversity of human gut viruses using highly enriched virome samples

Viruses are an abundant and crucial component of the human microbiome, but accurately discovering them via metagenomics is still challenging. Currently, the available viral reference genomes poorly represent the diversity in microbiome samples, and expanding such a set of viral references is difficult. As a result, many viruses are still undetectable through metagenomics even when considering the power of de novo metagenomic assembly and binning, as viruses lack universal markers. Here, we describe a novel approach to catalog new viral members of the human gut microbiome and show how the resulting resource improves metagenomic analyses. We retrieved >3,000 viral-like particles (VLP) enriched metagenomic samples (viromes), evaluated the efficiency of the enrichment in each sample to leverage the viromes of highest purity, and applied multiple analysis steps involving assembly and comparison with hundreds of thousands of metagenome-assembled genomes to discover new viral genomes. We reported over 162,000 viral sequences passing quality control from thousands of gut metagenomes and viromes. The great majority of the retrieved viral sequences (~94.4%) were of unknown origin, most had a CRISPR spacer matching host bacteria, and four of them could be detected in >50% of a set of 18,756 gut metagenomes we surveyed. We included the obtained collection of sequences in a new MetaPhlAn 4.1 release, which can quantify reads within a metagenome matching the known and newly uncovered viral diversity. Additionally, we released the viral database for further virome and metagenomic studies of the human microbiome.

ProkBERT family: genomic language models for microbiome applications

Background

In the evolving landscape of microbiology and microbiome analysis, the integration of machine learning is crucial for understanding complex microbial interactions, and predicting and recognizing novel functionalities within extensive datasets. However, the effectiveness of these methods in microbiology faces challenges due to the complex and heterogeneous nature of microbial data, further complicated by low signal-to-noise ratios, context-dependency, and a significant shortage of appropriately labeled datasets. This study introduces the ProkBERT model family, a collection of large language models, designed for genomic tasks. It provides a generalizable sequence representation for nucleotide sequences, learned from unlabeled genome data. This approach helps overcome the above-mentioned limitations in the field, thereby improving our understanding of microbial ecosystems and their impact on health and disease.

Methods

ProkBERT models are based on transfer learning and self-supervised methodologies, enabling them to use the abundant yet complex microbial data effectively. The introduction of the novel Local Context-Aware (LCA) tokenization technique marks a significant advancement, allowing ProkBERT to overcome the contextual limitations of traditional transformer models. This methodology not only retains rich local context but also demonstrates remarkable adaptability across various bioinformatics tasks.

Results

In practical applications such as promoter prediction and phage identification, the ProkBERT models show superior performance. For promoter prediction tasks, the top-performing model achieved a Matthews Correlation Coefficient (MCC) of 0.74 for E. coli and 0.62 in mixed-species contexts. In phage identification, ProkBERT models consistently outperformed established tools like VirSorter2 and DeepVirFinder, achieving an MCC of 0.85. These results underscore the models' exceptional accuracy and generalizability in both supervised and unsupervised tasks.

Conclusions

The ProkBERT model family is a compact yet powerful tool in the field of microbiology and bioinformatics. Its capacity for rapid, accurate analyses and its adaptability across a spectrum of tasks marks a significant advancement in machine learning applications in microbiology. The models are available on GitHub (https://github.com/nbrg-ppcu/prokbert) and HuggingFace (https://huggingface.co/nerualbioinfo) providing an accessible tool for the community.

Advances in bacteriophage-mediated strategies for combating polymicrobial biofilms

Bacteria and fungi tend to coexist within biofilms instead of in planktonic states. Usually, such communities include cross-kingdom microorganisms, which make them harder to remove from abiotic surfaces or infection sites. Additionally, the produced biofilm matrix protects embedded microorganisms from antibiotics, disinfectants, or the host immune system. Therefore, classic therapies based on antibiotics might be ineffective, especially when multidrug-resistant bacteria are causative factors. The complexities surrounding the eradication of biofilms from diverse surfaces and the human body have spurred the exploration of alternative therapeutic modalities. Among these options, bacteriophages and their enzymatic counterparts have emerged as promising candidates, either employed independently or in synergy with antibiotics and other agents. Phages are natural bacteria killers because of mechanisms of action that differ from antibiotics, phages might answer worldwide problems with bacterial infections. In this review, we report the attempts to use bacteriophages in combating polymicrobial biofilms in in vitro studies, using different models, including the therapeutical use of phages. In addition, we sum up the advantages, disadvantages, and perspectives of phage therapy.

Circular replication-associated protein-encoding single-stranded DNA virus with risk of spillover is widely prevalent in domestic animals in China

Circular replication-associated protein (Rep)-encoding single-stranded (CRESS) DNA viruses are highly diverse and have a broad range of hosts. In this study, we report the detection of Bo-Circo-like virus AH20-1 in the feces of diarrheal cattle. The virus has a circular genome of 3,912 nucleotides, three major putative open reading frames, and encodes a Rep gene of 310 amino acids. We found that the virus is closely related to the Bo-Circo-like virus CH strain, which belongs to the novel Kirkoviridae family. Furthermore, we conducted a nationwide surveillance program and found that the virus is prevalent in China (23.6%, 205/868), with the BCLa subtype being the predominant strain. Our findings suggest that the virus can infect sheep, highlighting the potential for cross-species transmission. Our pressure analysis indicates that the CRESS-DNA Kirkoviridae family has broad host adaptation, and that selection pressure played an important role in the evolution of its Rep genes. Our study underscores the need for continued epidemiological surveillance of this virus due to its widespread prevalence in our ruminant population and potential for cross-species transmission.

Role of bacteriophages in shaping gut microbial community

Phages are the most diversified and dominant members of the gut virobiota. They play a crucial role in shaping the structure and function of the gut microbial community and consequently the health of humans and animals. Phages are found mainly in the mucus, from where they can translocate to the intestinal organs and act as a modulator of gut microbiota. Understanding the vital role of phages in regulating the composition of intestinal microbiota and influencing human and animal health is an emerging area of research. The relevance of phages in the gut ecosystem is supported by substantial evidence, but the importance of phages in shaping the gut microbiota remains unclear. Although information regarding general phage ecology and development has accumulated, detailed knowledge on phage-gut microbe and phage-human interactions is lacking, and the information on the effects of phage therapy in humans remains ambiguous. In this review, we systematically assess the existing data on the structure and ecology of phages in the human and animal gut environments, their development, possible interaction, and subsequent impact on the gut ecosystem dynamics. We discuss the potential mechanisms of prophage activation and the subsequent modulation of gut bacteria. We also review the link between phages and the immune system to collect evidence on the effect of phages on shaping the gut microbial composition. Our review will improve understanding on the influence of phages in regulating the gut microbiota and the immune system and facilitate the development of phage-based therapies for maintaining a healthy and balanced gut microbiota.

The infant gut virome is associated with preschool asthma risk independently of bacteria

Bacteriophage (also known as phage) communities that inhabit the gut have a major effect on the structure and functioning of bacterial populations, but their roles and association with health and disease in early life remain unknown. Here, we analyze the gut virome of 647 children aged 1 year from the Copenhagen Prospective Studies on Asthma in Childhood2010 (COPSAC2010) mother-child cohort, all deeply phenotyped from birth and with longitudinally assessed asthma diagnoses. Specific temperate gut phage taxa were found to be associated with later development of asthma. In particular, the joint abundances of 19 caudoviral families were found to significantly contribute to this association. Combining the asthma-associated virome and bacteriome signatures had additive effects on asthma risk, implying an independent virome-asthma association. Moreover, the virome-associated asthma risk was modulated by the host TLR9 rs187084 gene variant, suggesting a direct interaction between phages and the host immune system. Further studies will elucidate whether phages, alongside bacteria and host genetics, can be used as preclinical biomarkers for asthma.

LAMP assay coupled with a CRISPR/Cas12a system for the rapid and ultrasensitive detection of porcine circovirus-like virus in the field

A recent outbreak of porcine circovirus-like virus (PCLV), a virus that may be associated with porcine diarrhea, has been reported in swine herds in China. The virus is spreading rapidly, causing huge economic losses to the swine farming industry. To achieve the rapid, inexpensive, and sensitive detection of PCLV, we combined loop-mediated isothermal amplification (LAMP) and the CRISPR/Cas12a system, whose fluorescence intensity readout can detect PCLV ORF4 gene levels as low as 10 copies. To overcome the need for sophisticated equipment, lateral flow strip reading technology was introduced for the first time in a LAMP-Cas12a-based system to detect PCLV. The lateral flow strip (LFS) results were readout by the naked eye, and the method was highly sensitive with a detection limit of 10 copies, with a detection time of about 60 min. In addition, the method is highly specific and has no cross-reactivity with other related viruses. In conclusion, LAMP-CRISPR/Cas12a-based assays have the advantages of rapidity, accuracy, portability, low cost, and visualization of the results. They therefore have great potential, especially for areas where specialized equipment is lacking, and can expect to be an ideal method for early diagnosis and on-site detection of PCLV.

Identification of small circular DNA viruses in coyote fecal samples from Arizona (USA)

Coyotes (Canis latrans) have a broad geographic distribution across North and Central America. Despite their widespread presence in urban environments in the USA, there is limited information regarding viruses associated with coyotes in the USA and in particular the state of Arizona. To explore viruses associated with coyotes, particularly small DNA viruses, 44 scat samples were collected (April-June 2021 and November 2021-January 2022) along the Salt River near Phoenix, Arizona (USA), along 43 transects (500 m). From these samples, we identified 11 viral genomes: two novel circoviruses, six unclassified cressdnaviruses, and two anelloviruses. One of the circoviruses is most closely related to a circovirus sequence identified from an aerosolized dust sample in Arizona, USA. The second circovirus is most closely related to a rodent-associated circovirus and canine circovirus. Of the unclassified cressdnaviruses, three encode replication-associated proteins that are similar to those found in protists (Histomonas meleagridis and Monocercomonoides exilis), implying an evolutionary relationship with or a connection to similar unidentified protist hosts. The two anelloviruses are most closely related to those found in rodents, and this suggests a diet-related identification.

De Novo Synthesis of a Conjugative System from Human Gut Metagenomic Data for Targeted Delivery of Cas9 Antimicrobials

Metagenomic sequences represent an untapped source of genetic novelty, particularly for conjugative systems that could be used for plasmid-based delivery of Cas9-derived antimicrobial agents. However, unlocking the functional potential of conjugative systems purely from metagenomic sequences requires the identification of suitable candidate systems as starting scaffolds for de novo DNA synthesis. Here, we developed a bioinformatics approach that searches through the metagenomic "trash bin" for genes associated with conjugative systems present on contigs that are typically excluded from common metagenomic analysis pipelines. Using a human metagenomic gut data set representing 2805 taxonomically distinct units, we identified 1598 contigs containing conjugation genes with a differential distribution in human cohorts. We synthesized de novo an entire Citrobacter spp. conjugative system of 54 kb containing at least 47 genes and assembled it into a plasmid, pCitro. We found that pCitro conjugates from Escherichia coli to Citrobacter rodentium with a 30-fold higher frequency than to E. coli, and is compatible with Citrobacter resident plasmids. Mutations in the traV and traY conjugation components of pCitro inhibited conjugation. We showed that pCitro can be repurposed as an antimicrobial delivery agent by programming it with the TevCas9 nuclease and Citrobacter-specific sgRNAs to kill C. rodentium. Our study reveals a trove of uncharacterized conjugative systems in metagenomic data and describes an experimental framework to animate these large genetic systems as novel target-adapted delivery vectors for Cas9-based editing of bacterial genomes.

Exploring the Human Virome: Composition, Dynamics, and Implications for Health and Disease

Humans are colonized by large number of microorganisms-bacteria, fungi, and viruses. The overall genome of entire viruses that either lives on or inside the human body makes up the human virome and is indeed an essential fraction of the human metagenome. Humans are constantly exposed to viruses as they are ubiquitously present on earth. The human virobiota encompasses eukaryotic viruses, bacteriophages, retroviruses, and even giant viruses. With the advent of Next-generation sequencing (NGS) and ongoing development of numerous bioinformatic softwares, identification and taxonomic characterization of viruses have become easier. The viruses are abundantly present in humans; these can be pathogenic or commensal. The viral communities occupy various niches in the human body. The viruses start colonizing the infant gut soon after birth in a stepwise fashion and the viral composition diversify according to their feeding habits. Various factors such as diet, age, medications, etc. influence and shape the human virome. The viruses interact with the host immune system and these interactions have beneficial or detrimental effects on their host. The virome composition and abundance change during the course of disease and these alterations impact the immune system. Hence, the virome population in healthy and disease conditions influences the human host in numerous ways. This review presents an overview of assembly and composition of the human virome in healthy asymptomatic individuals, changes in the virome profiles, and host-virome interactions in various disease states.

Virome in immunodeficiency: what we know currently

ABSTRACT

Over the past few years, the human virome and its complex interactions with microbial communities and the immune system have gained recognition as a crucial factor in human health. Individuals with compromised immune function encounter distinctive challenges due to their heightened vulnerability to a diverse range of infectious diseases. This review aims to comprehensively explore and analyze the growing evidence regarding the role of the virome in immunocompromised disease status. By surveying the latest literature, we present a detailed overview of virome alterations observed in various immunodeficiency conditions. We then delve into the influence and mechanisms of these virome changes on the pathogenesis of specific diseases in immunocompromised individuals. Furthermore, this review explores the clinical relevance of virome studies in the context of immunodeficiency, highlighting the potential diagnostic and therapeutic gains from a better understanding of virome contributions to disease manifestations.

Metagenomic analysis of herbivorous mammalian viral communities in the Northwest Plateau

BACKGROUND

Mammals are potential hosts for many infectious diseases. However, studies on the viral communities of herbivorous mammals in the Northwest Plateau are limited. Here, we studied the viral communities of herbivorous mammals in the Northwest Plateau using virus metagenomic analysis to analyze and compare the viral community composition of seven animal species.

RESULTS

By library construction and next-generation sequencing, contigs and singlets reads with similar viral sequences were classified into 24 viral families. Analyzed from the perspective of sampling areas, the virus community composition was relatively similar in two areas of Wuwei and Jinchang, Gansu Province. Analyzed from the perspective of seven animal species, the viral reads of seven animal species were mostly ssDNA and dominated by CRESS-DNA viruses. Phylogenetic analysis based on viral marker genes indicated that CRESS-DNA viruses and microviruses have high genetic diversity. In addition to DNA viruses, nodaviruses, pepper mild mottle viruses and picornaviruses were RNA viruses that we performed by phylogenetic analysis. The CRESS-DNA viruses and nodaviruses are believed to infect plants and insects, and microviruses can infect bacteria, identifying that they were likely from the diet of herbivorous mammals. Notably, two picornaviruses were identified from red deer and wild horse, showing that the picornavirus found in red deer had the relatively high similarity with human hepatitis A virus, and the picornavirus carried by wild horse could potentially form a new species within the Picornaviridae family.

CONCLUSIONS

This study explored the herbivorous mammalian virus community in the Northwest Plateau and the genetic characteristics of viruses that potentially threaten human health. It reveals the diversity and stability of herbivorous mammalian virus communities in the Northwest Plateau and helps to expand our knowledge of various herbivorous mammalian potentially pathogenic viruses.

Stimulator of Interferon Genes (STING) Triggers Adipocyte Autophagy

Innate immune signaling in adipocytes affects systemic metabolism. Cytosolic nucleic acid sensing has been recently shown to stimulate thermogenic adipocyte differentiation and protect from obesity; however, DNA efflux from adipocyte mitochondria is a potential proinflammatory signal that causes adipose tissue dysfunction and insulin resistance. Cytosolic DNA activates the stimulator of interferon response genes (STING), a key signal transducer which triggers type I interferon (IFN-I) expression; hence, STING activation is expected to induce IFN-I response and adipocyte dysfunction. However, we show herein that mouse adipocytes had a diminished IFN-I response to STING stimulation by 2'3'-cyclic-GMP-AMP (cGAMP). We also show that cGAMP triggered autophagy in murine and human adipocytes. In turn, STING inhibition reduced autophagosome number, compromised the mitochondrial network and caused inflammation and fat accumulation in adipocytes. STING hence stimulates a process that removes damaged mitochondria, thereby protecting adipocytes from an excessive IFN-I response to mitochondrial DNA efflux. In summary, STING appears to limit inflammation in adipocytes by promoting mitophagy under non-obesogenic conditions.

The old friends hypothesis: evolution, immunoregulation and essential microbial inputs

In wealthy urbanised societies there have been striking increases in chronic inflammatory disorders such as allergies, autoimmunity and inflammatory bowel diseases. There has also been an increase in the prevalence of individuals with systemically raised levels of inflammatory biomarkers correlating with increased risk of metabolic, cardiovascular and psychiatric problems. These changing disease patterns indicate a broad failure of the mechanisms that should stop the immune system from attacking harmless allergens, components of self or gut contents, and that should terminate inappropriate inflammation. The Old Friends Hypothesis postulates that this broad failure of immunoregulation is due to inadequate exposures to the microorganisms that drive development of the immune system, and drive the expansion of components such as regulatory T cells (Treg) that mediate immunoregulatory mechanisms. An evolutionary approach helps us to identify the organisms on which we are in a state of evolved dependence for this function (Old Friends). The bottom line is that most of the organisms that drive the regulatory arm of the immune system come from our mothers and family and from the natural environment (including animals) and many of these organisms are symbiotic components of a healthy microbiota. Lifestyle changes that are interrupting our exposure to these organisms can now be identified, and many are closely associated with low socioeconomic status (SES) in wealthy countries. These insights will facilitate the development of education, diets and urban planning that can correct the immunoregulatory deficit, while simultaneously reducing other contributory factors such as epithelial damage.

Human Neutrophil Response to Pseudomonas Bacteriophage PAK_P1, a Therapeutic Candidate

The immune system offers several mechanisms of response to harmful microbes that invade the human body. As a first line of defense, neutrophils can remove pathogens by phagocytosis, inactivate them by the release of reactive oxygen species (ROS) or immobilize them by neutrophil extracellular traps (NETs). Although recent studies have shown that bacteriophages (phages) make up a large portion of human microbiomes and are currently being explored as antibacterial therapeutics, neutrophilic responses to phages are still elusive. Here, we show that exposure of isolated human resting neutrophils to a high concentration of the Pseudomonas phage PAK_P1 led to a 2-fold increase in interleukin-8 (IL-8) secretion. Importantly, phage exposure did not induce neutrophil apoptosis or necrosis and did not further affect activation marker expression, oxidative burst, and NETs formation. Similarly, inflammatory stimuli-activated neutrophil effector responses were unaffected by phage exposure. Our work suggests that phages are unlikely to inadvertently cause excessive neutrophil responses that could damage tissues and worsen disease. Because IL-8 functions as a chemoattractant, directing immune cells to sites of infection and inflammation, phage-stimulated IL-8 production may modulate some host immune responses.

Chronic kidney disease and gut microbiota

Chronic kidney disease (CKD) refers to a range of various pathophysiological processes correlated with abnormal renal function and a progressive loss in GFR. Just as dysbiosis and altered pathology of the gut are accompanied with hypertension, which is a significant CKD risk factor. Gut dysbiosis in CKD patients is associated with an elevated levels of uremic toxins, which in turn increases the CKD progression. According to research results, the gut-kidney axis has a role in the formation of kidney stones, also in IgAN. A number of researchers have categorized the gut microbiota as enterotypes, and others, skeptical of theory of enterotypes, have suggested biomarkers to describe taxa that related to lifestyle, nutrition, and disease status. Metabolome-microbiome studies have been used to investigate the interactions of host-gut microbiota in terms of the involvement of metabolites in these interactions and are yielded promising results. The correlation between gut microbiota and CKD requires further multi-omic researches. Also, with regard to systems biology, studies on the communication network of proteins and transporters such as SLC and ABC, can help us achieve a deeper understanding of the gut-liver-kidney axis communication and can thus provide promising new horizons in the treatment of CKD patients. Probiotic-based treatment is an approach to reduce uremic poisoning, which is accomplished by swallowing microbes those can catalyze URS in the gut. If further comprehensive studies are carried out, we will know about the probiotics impact in slowing the renal failure progression and reducing inflammatory markers.

RNA-Seq Virus Fraction in Lake Baikal and Treated Wastewaters

In this study, we analyzed the transcriptomes of RNA and DNA viruses from the oligotrophic water of Lake Baikal and the effluent from wastewater treatment plants (WWTPs) discharged into the lake from the towns of Severobaikalsk and Slyudyanka located on the lake shores. Given the uniqueness and importance of Lake Baikal, the issues of biodiversity conservation and the monitoring of potential virological hazards to hydrobionts and humans are important. Wastewater treatment plants discharge treated effluent directly into the lake. In this context, the identification and monitoring of allochthonous microorganisms entering the lake play an important role. Using high-throughput sequencing methods, we found that dsDNA-containing viruses of the class Caudoviricetes were the most abundant in all samples, while Leviviricetes (ssRNA(+) viruses) dominated the treated water samples. RNA viruses of the families Nodaviridae, Tombusviridae, Dicitroviridae, Picobirnaviridae, Botourmiaviridae, Marnaviridae, Solemoviridae, and Endornavirida were found in the pelagic zone of three lake basins. Complete or nearly complete genomes of RNA viruses belonging to such families as Dicistroviridae, Marnaviridae, Blumeviridae, Virgaviridae, Solspiviridae, Nodaviridae, and Fiersviridae and the unassigned genus Chimpavirus, as well as unclassified picorna-like viruses, were identified. In general, the data of sanitary/microbiological and genetic analyses showed that WWTPs inadequately purify the discharged water, but, at the same time, we did not observe viruses pathogenic to humans in the pelagic zone of the lake.

The gut virome and the relevance of temperate phages in human health

Alterations in the gut virome impact human health. Bacteriophages, viruses that infect bacteria, dominate the gut virome and are mainly composed by virulent and temperate phages. While virulent phages exclusively replicate within and lyse their bacterial host's cell, temperate phages switch from an integrated state residing within their bacterial host's chromosome to an induced free virion state via an induction event. How often do these induction events occur and what are their implications on gut homeostasis? Here, we summarize the current knowledge of the gut virome based on metagenomics and present how the proportion of induced temperate phages varies amongst individuals, age, and disease states. Finally, we highlight the importance of building upon classical culture-dependent techniques and sequencing approaches to improve our understanding of temperate phages to enable their potential therapeutic use.

Enteroviruses and risk of islet autoimmunity or type 1 diabetes: systematic review and meta-analysis of controlled observational studies detecting viral nucleic acids and proteins

BACKGROUND

Enteroviruses are routinely detected with molecular methods within large cohorts that are at risk of type 1 diabetes. We aimed to examine the association between enteroviruses and either islet autoimmunity or type 1 diabetes.

METHODS

For this systematic review and meta-analysis, we searched PubMed and Embase for controlled observational studies from inception until Jan 1, 2023. Cohort or case-control studies were eligible if enterovirus RNA or protein were detected in individuals with outcomes of islet autoimmunity or type 1 diabetes. Studies in pregnancy or other types of diabetes were excluded. Data extraction and appraisal involved author contact and deduplication, which was done independently by three reviewers. Study quality was assessed with the Newcastle-Ottawa Scale and National Health and Medical Research Council levels of evidence. Pooled and subgroup meta-analyses were done in RevMan version 5.4, with random effects models and Mantel-Haenszel odds ratios (ORs; 95% CIs). The study is registered with PROSPERO, CRD42021278863.

FINDINGS

The search returned 3266 publications, with 897 full texts screened. Following deduplication, 113 eligible records corresponded to 60 studies (40 type 1 diabetes; nine islet autoimmunity; 11 both), comprising 12077 participants (5981 cases; 6096 controls). Study design and quality varied, generating substantial statistical heterogeneity. Meta-analysis of 56 studies showed associations between enteroviruses and islet autoimmunity (OR 2·1, 95% CI 1·3-3·3; p=0·002; n=18; heterogeneity χ²/df 2·69; p=0·0004; I²=63%), type 1 diabetes (OR 8·0, 95% CI 4·9-13·0; p<0·0001; n=48; χ²/df 6·75; p<0·0001; I²=85%), or within 1 month of type 1 diabetes (OR 16·2, 95% CI 8·6-30·5; p<0·0001; n=28; χ²/df 3·25; p<0·0001; I²=69%). Detection of either multiple or consecutive enteroviruses was associated with islet autoimmunity (OR 2·0, 95% CI 1·0-4·0; p=0·050; n=8). Detection of Enterovirus B was associated with type 1 diabetes (OR 12·7, 95% CI 4·1-39·1; p<0·0001; n=15).

INTERPRETATION

These findings highlight the association between enteroviruses and islet autoimmunity or type 1 diabetes. Our data strengthen the rationale for vaccine development targeting diabetogenic enterovirus types, particularly those within Enterovirus B. Prospective studies of early life are needed to elucidate the role of enterovirus timing, type, and infection duration on the initiation of islet autoimmunity and the progression to type 1 diabetes.

FUNDING

Environmental Determinants of Islet Autoimmunity, European Association for the Study of Diabetes, JDRF, Australian National Health and Medical Research Council, and University of New South Wales.

The human gut virome: composition, colonization, interactions, and impacts on human health

The gut virome is an incredibly complex part of the gut ecosystem. Gut viruses play a role in many disease states, but it is unknown to what extent the gut virome impacts everyday human health. New experimental and bioinformatic approaches are required to address this knowledge gap. Gut virome colonization begins at birth and is considered unique and stable in adulthood. The stable virome is highly specific to each individual and is modulated by varying factors such as age, diet, disease state, and use of antibiotics. The gut virome primarily comprises bacteriophages, predominantly order Crassvirales, also referred to as crAss-like phages, in industrialized populations and other Caudoviricetes (formerly Caudovirales). The stability of the virome's regular constituents is disrupted by disease. Transferring the fecal microbiome, including its viruses, from a healthy individual can restore the functionality of the gut. It can alleviate symptoms of chronic illnesses such as colitis caused by Clostridiodes difficile. Investigation of the virome is a relatively novel field, with new genetic sequences being published at an increasing rate. A large percentage of unknown sequences, termed 'viral dark matter', is one of the significant challenges facing virologists and bioinformaticians. To address this challenge, strategies include mining publicly available viral datasets, untargeted metagenomic approaches, and utilizing cutting-edge bioinformatic tools to quantify and classify viral species. Here, we review the literature surrounding the gut virome, its establishment, its impact on human health, the methods used to investigate it, and the viral dark matter veiling our understanding of the gut virome.

Chromosome folding and prophage activation reveal specific genomic architecture for intestinal bacteria

BACKGROUND

Bacteria and their viruses, bacteriophages, are the most abundant entities of the gut microbiota, a complex community of microorganisms associated with human health and disease. In this ecosystem, the interactions between these two key components are still largely unknown. In particular, the impact of the gut environment on bacteria and their associated prophages is yet to be deciphered.

RESULTS

To gain insight into the activity of lysogenic bacteriophages within the context of their host genomes, we performed proximity ligation-based sequencing (Hi-C) in both in vitro and in vivo conditions on the 12 bacterial strains of the OMM12 synthetic bacterial community stably associated within mice gut (gnotobiotic mouse line OMM12). High-resolution contact maps of the chromosome 3D organization of the bacterial genomes revealed a wide diversity of architectures, differences between environments, and an overall stability over time in the gut of mice. The DNA contacts pointed at 3D signatures of prophages leading to 16 of them being predicted as functional. We also identified circularization signals and observed different 3D patterns between in vitro and in vivo conditions. Concurrent virome analysis showed that 11 of these prophages produced viral particles and that OMM12 mice do not carry other intestinal viruses.

CONCLUSIONS

The precise identification by Hi-C of functional and active prophages within bacterial communities will unlock the study of interactions between bacteriophages and bacteria across conditions (healthy vs disease). Video Abstract.

Beyond pathogenesis: Detecting the full spectrum of ecological interactions in the virosphere

The public perception of viruses has historically been negative. We are now at a stage where the development of tools to study viruses is at an all-time high, but society's perception of viruses is at an all-time low. The literature regarding viral interactions has been skewed towards negative (i.e., pathogenic) symbioses, whereas viral mutualisms remain relatively underexplored. Viral interactions with their hosts are complex and some non-pathogenic viruses could have potential benefits to society. However, viral research is seldom designed to identify viral mutualists, a gap that merits considering new experimental designs. Determining whether antagonisms, mutualisms, and commensalisms are equally common ecological strategies requires more balanced research efforts that characterize the full spectrum of viral interactions.

Altered human gut virome in patients undergoing antibiotics therapy for Helicobacter pylori

Transient gut microbiota alterations have been reported after antibiotic therapy for Helicobacter pylori. However, alteration in the gut virome after H. pylori eradication remains uncertain. Here, we apply metagenomic sequencing to fecal samples of 44 H. pylori-infected patients at baseline, 6-week (N = 44), and 6-month (N = 33) after treatment. Following H. pylori eradication, we discover contraction of the gut virome diversity, separation of virome community with increased community difference, and shifting towards a higher proportion of core virus. While the gut microbiota is altered at 6-week and restored at 6-month, the virome community shows contraction till 6-month after the treatment with enhanced phage-bacteria interactions at 6-week. Multiple courses of antibiotic treatments further lead to lower virus community diversity when compared with treatment naive patients. Our results demonstrate that H. pylori eradication therapies not only result in transient alteration in gut microbiota but also significantly alter the previously less known gut virome community.

Expanding known viral diversity in the healthy infant gut

The gut microbiome is shaped through infancy and impacts the maturation of the immune system, thus protecting against chronic disease later in life. Phages, or viruses that infect bacteria, modulate bacterial growth by lysis and lysogeny, with the latter being especially prominent in the infant gut. Viral metagenomes (viromes) are difficult to analyse because they span uncharted viral diversity, lacking marker genes and standardized detection methods. Here we systematically resolved the viral diversity in faecal viromes from 647 1-year-olds belonging to Copenhagen Prospective Studies on Asthma in Childhood 2010, an unselected Danish cohort of healthy mother-child pairs. By assembly and curation we uncovered 10,000 viral species from 248 virus family-level clades (VFCs). Most (232 VFCs) were previously unknown, belonging to the Caudoviricetes viral class. Hosts were determined for 79% of phage using clustered regularly interspaced short palindromic repeat spacers within bacterial metagenomes from the same children. Typical Bacteroides-infecting crAssphages were outnumbered by undescribed phage families infecting Clostridiales and Bifidobacterium. Phage lifestyles were conserved at the viral family level, with 33 virulent and 118 temperate phage families. Virulent phages were more abundant, while temperate ones were more prevalent and diverse. Together, the viral families found in this study expand existing phage taxonomy and provide a resource aiding future infant gut virome research.

Maternal provisions in type 1 diabetes: Evidence for both protective & pathogenic potential

Maternal influences on the immune health and development of an infant begin in utero and continue well into the postnatal period, shaping and educating the child's maturing immune system. Two maternal provisions include early microbial colonizers to initiate microbiota establishment and the transfer of antibodies from mother to baby. Maternal antibodies are a result of a lifetime of antigenic experience, reflecting the infection history, health and environmental exposure of the mother. These same factors are strong influencers of the microbiota, inexorably linking the two. Together, these provisions help to educate the developing neonatal immune system and shape lymphocyte repertoires, establishing a role for external environmental influences even before birth. In the context of autoimmunity, the transfer of maternal autoantibodies has the potential to be harmful for the child, sometimes targeting tissues and cells with devastating consequences. Curiously, this does not seem to apply to maternal autoantibody transfer in type 1 diabetes (T1D). Moreover, despite the rising prevalence of the disease, little research has been conducted on the effects of maternal dysbiosis or antibody transfer from an affected mother to her offspring and thus their relevance to disease development in the offspring remains unclear. This review seeks to provide a thorough evaluation of the role of maternal microorganisms and antibodies within the context of T1D, exploring both their pathogenic and protective potential. Although a definitive understanding of their significance in infant T1D development remains elusive at present, we endeavor to present what has been learned with the goal of spurring further interest in this important and intriguing question.

Interpersonal variability of the human gut virome confounds disease signal detection in IBD

Viruses are increasingly recognised as important components of the human microbiome, fulfilling numerous ecological roles including bacterial predation, immune stimulation, genetic diversification, horizontal gene transfer, microbial interactions, and augmentation of metabolic functions. However, our current view of the human gut virome is tainted by previous sequencing requirements that necessitated the amplification of starting nucleic acids. In this study, we performed an original longitudinal analysis of 40 healthy control, 19 Crohn's disease, and 20 ulcerative colitis viromes over three time points without an amplification bias, which revealed and highlighted the interpersonal individuality of the human gut virome. In contrast to a 16 S rRNA gene analysis of matched samples, we show that α- and β-diversity metrics of unamplified viromes are not as efficient at discerning controls from patients with inflammatory bowel disease. Additionally, we explored the intrinsic properties of unamplified gut viromes and show there is considerable interpersonal variability in viral taxa, infrequent longitudinal persistence of intrapersonal viruses, and vast fluctuations in the abundance of temporal viruses. Together, these properties of unamplified faecal viromes confound the ability to discern disease associations but significantly advance toward an unbiased and accurate representation of the human gut virome.

Gut Microbiome and Neurodevelopmental Disorders: A Link Yet to Be Disclosed

Τhe importance of the gut microbiome and its functions has only recently been recognized and researched in greater depth. The establishment of the human gut microbiome begins in utero, forming its adult-like phenotype in the first 2-3 years of life. Several factors affect and alter the gut microbiome composition and its metabolic functions, such as early onset of breastfeeding, mode of delivery, antibiotic administration, or exposure to chemical substances, among others. Existing data support the important connection between health status and gut microbiome homeostasis. In cases when this balance is disturbed, several disorders may arise, such as inflammatory reactions that lead to atopy, eczema, or allergic asthma. The so-called gut-brain axis refers to the complex biochemical pathways between the central nervous system and the gastrointestinal system. One of the most fascinating areas of ongoing research is the broad spectrum of neurodevelopmental disorders (NDDs) and how gut health may be associated with such disorders. The prevalence of NDDs, such as autism spectrum disorder or attention deficit hyperactivity disorder, has increased over recent years. Whether gut microbiota homeostasis plays a role in these disorders is not yet fully understood. The aim of this narrative review is to provide an account of current knowledge on how gut health is linked with these disorders. We performed a literature review in order to identify and synthesize available data that highlights the potential association between NDDs and a balanced gut microbiome in terms of composition and proper function. The connection between the gut microbiome and NDDs offers promising new opportunities for future research.

Disturbed gut virome with potent interferonogenic property in systemic lupus erythematosus

Accumulating evidence suggests an essential role of disturbed gut microbiota in the etiopathogenesis of systemic lupus erythematosus (SLE), but it remains unclear as to gut virome. In this study, fecal virus-like particles (VLPs) isolated from 76 non-treated SLE patients and 75 healthy controls were subjected to gut virome profiling. The proportion of bacteriophages was significantly elevated in the SLE gut, and the altered viral taxa were correlated with clinical parameters. Gut virome and bacteriome were closely associated with each other in SLE patients. The combination of gut viral and bacterial markers displayed better performance in distinguishing SLE patients from healthy controls. Further, VLPs from non-treated SLE patients promoted interferon-α production in an epithelial cell line and human immune cells. Intriguingly, the interferon-stimulatory capacity diminished in VLPs from post-treated SLE patients. Our findings may shed novel insights into SLE pathogenesis. Further in-depth understanding of gut virome might help develop future biomarkers and therapeutics for SLE patients.

The Human Gut Virome and Its Relationship with Nontransmissible Chronic Diseases

The human gastrointestinal tract contains large communities of microorganisms that are in constant interaction with the host, playing an essential role in the regulation of several metabolic processes. Among the gut microbial communities, the gut bacteriome has been most widely studied in recent decades. However, in recent years, there has been increasing interest in studying the influences that other microbial groups can exert on the host. Among them, the gut virome is attracting great interest because viruses can interact with the host immune system and metabolic functions; this is also the case for phages, which interact with the bacterial microbiota. The antecedents of virome-rectification-based therapies among various diseases were also investigated. In the near future, stool metagenomic investigation should include the identification of bacteria and phages, as well as their correlation networks, to better understand gut microbiota activity in metabolic disease progression.

Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the 'Bystander' Activation of Memory CD8+ T Cells

Type 1 diabetes mellitus (T1DM) arises from the failure of pancreatic β-cells to produce adequate insulin, usually as a consequence of extensive pancreatic β-cell destruction. T1DM is classed as an immune-mediated condition. However, the processes that drive pancreatic β-cell apoptosis remain to be determined, resulting in a failure to prevent ongoing cellular destruction. Alteration in mitochondrial function is clearly the major pathophysiological process underpinning pancreatic β-cell loss in T1DM. As with many medical conditions, there is a growing interest in T1DM as to the role of the gut microbiome, including the interactions of gut bacteria with Candida albicans fungal infection. Gut dysbiosis and gut permeability are intimately associated with raised levels of circulating lipopolysaccharide and suppressed butyrate levels, which can act to dysregulate immune responses and systemic mitochondrial function. This manuscript reviews broad bodies of data on T1DM pathophysiology, highlighting the importance of alterations in the mitochondrial melatonergic pathway of pancreatic β-cells in driving mitochondrial dysfunction. The suppression of mitochondrial melatonin makes pancreatic β-cells susceptible to oxidative stress and dysfunctional mitophagy, partly mediated by the loss of melatonin's induction of PTEN-induced kinase 1 (PINK1), thereby suppressing mitophagy and increasing autoimmune associated major histocompatibility complex (MHC)-1. The immediate precursor to melatonin, N-acetylserotonin (NAS), is a brain-derived neurotrophic factor (BDNF) mimic, via the activation of the BDNF receptor, TrkB. As both the full-length and truncated TrkB play powerful roles in pancreatic β-cell function and survival, NAS is another important aspect of the melatonergic pathway relevant to pancreatic β-cell destruction in T1DM. The incorporation of the mitochondrial melatonergic pathway in T1DM pathophysiology integrates wide bodies of previously disparate data on pancreatic intercellular processes. The suppression of Akkermansia muciniphila, Lactobacillus johnsonii, butyrate, and the shikimate pathway-including by bacteriophages-contributes to not only pancreatic β-cell apoptosis, but also to the bystander activation of CD8⁺ T cells, which increases their effector function and prevents their deselection in the thymus. The gut microbiome is therefore a significant determinant of the mitochondrial dysfunction driving pancreatic β-cell loss as well as 'autoimmune' effects derived from cytotoxic CD8⁺ T cells. This has significant future research and treatment implications.

Rhizosphere phage communities drive soil suppressiveness to bacterial wilt disease

BACKGROUND

Bacterial viruses, phages, play a key role in nutrient turnover and lysis of bacteria in terrestrial ecosystems. While phages are abundant in soils, their effects on plant pathogens and rhizosphere bacterial communities are poorly understood. Here, we used metagenomics and direct experiments to causally test if differences in rhizosphere phage communities could explain variation in soil suppressiveness and bacterial wilt plant disease outcomes by plant-pathogenic Ralstonia solanacearum bacterium. Specifically, we tested two hypotheses: (1) that healthy plants are associated with stronger top-down pathogen control by R. solanacearum-specific phages (i.e. 'primary phages') and (2) that 'secondary phages' that target pathogen-inhibiting bacteria play a stronger role in diseased plant rhizosphere microbiomes by indirectly 'helping' the pathogen.

RESULTS

Using a repeated sampling of tomato rhizosphere soil in the field, we show that healthy plants are associated with distinct phage communities that contain relatively higher abundances of R. solanacearum-specific phages that exert strong top-down pathogen density control. Moreover, 'secondary phages' that targeted pathogen-inhibiting bacteria were more abundant in the diseased plant microbiomes. The roles of R. solanacearum-specific and 'secondary phages' were directly validated in separate greenhouse experiments where we causally show that phages can reduce soil suppressiveness, both directly and indirectly, via top-down control of pathogen densities and by alleviating interference competition between pathogen-inhibiting bacteria and the pathogen.

CONCLUSIONS

Together, our findings demonstrate that soil suppressiveness, which is most often attributed to bacteria, could be driven by rhizosphere phage communities that regulate R. solanacearum densities and strength of interference competition with pathogen-suppressing bacteria. Rhizosphere phage communities are hence likely to be important in determining bacterial wilt disease outcomes and soil suppressiveness in agricultural fields. Video Abstract.

The Emerging Role of the Gut Virome in Health and Inflammatory Bowel Disease: Challenges, Covariates and a Viral Imbalance

Virome research is a rapidly growing area in the microbiome field that is increasingly associated with human diseases, such as inflammatory bowel disease (IBD). Although substantial progress has been made, major methodological challenges limit our understanding of the virota. In this review, we describe challenges that must be considered to accurately report the virome composition and the current knowledge on the virome in health and IBD. First, the description of the virome shows strong methodological biases related to wetlab (e.g., VLP enrichment) and bioinformatics approaches (viral identification and classification). Second, IBD patients show consistent viral imbalances characterized by a high relative abundance of phages belonging to the Caudovirales and a low relative abundance of phages belonging to the Microviridae. Simultaneously, a sporadic contraction of CrAss-like phages and a potential expansion of the lysogenic potential of the intestinal virome are observed. Finally, despite numerous studies that have conducted diversity analysis, it is difficult to draw firm conclusions due to methodological biases. Overall, we present the many methodological and environmental factors that influence the virome, its current consensus in health and IBD, and a contributing hypothesis called the "positive inflammatory feedback loop" that may play a role in the pathophysiology of IBD.

Virus induced dysbiosis promotes type 1 diabetes onset

Autoimmune disorders are complex diseases of unclear etiology, although evidence suggests that the convergence of genetic susceptibility and environmental factors are critical. In type 1 diabetes (T1D), enterovirus infection and disruption of the intestinal microbiota are two environmental factors that have been independently associated with T1D onset in both humans and animal models. However, the possible interaction between viral infection and the intestinal microbiota remains unknown. Here, we demonstrate that Coxsackievirus B4 (CVB4), an enterovirus that accelerates T1D onset in non-obese diabetic (NOD) mice, induced restructuring of the intestinal microbiome prior to T1D onset. Microbiome restructuring was associated with an eroded mucosal barrier, bacterial translocation to the pancreatic lymph node, and increased circulating and intestinal commensal-reactive antibodies. The CVB4-induced change in community composition was strikingly similar to that of uninfected NOD mice that spontaneously developed diabetes, implying a mutual "diabetogenic" microbiome. Notably, members of the Bifidobacteria and Akkermansia genera emerged as conspicuous members of this diabetogenic microbiome, implicating these taxa, among others, in diabetes onset. Further, fecal microbiome transfer (FMT) of the diabetogenic microbiota from CVB4-infected mice enhanced T1D susceptibility and led to diminished expression of the short chain fatty acid receptor GPR43 and fewer IL-10-expressing regulatory CD4⁺ T cells in the intestine of naïve NOD recipients. These findings support an overlap in known environmental risk factors of T1D, and suggest that microbiome disruption and impaired intestinal homeostasis contribute to CVB-enhanced autoreactivity and T1D.

Candida albicans-enteric viral interactions-The prostaglandin E2 connection and host immune responses

The human microbiome comprises trillions of microorganisms residing within different mucosal cavities and across the body surface. The gut microbiota modulates host susceptibility to viral infections in several ways, and microbial interkingdom interactions increase viral infectivity within the gut. Candida albicans, a frequently encountered fungal species in the gut, produces highly structured biofilms and eicosanoids such as prostaglandin E₂ (PGE₂), which aid in viral protection and replication. These biofilms encompass viruses and provide a shield from antiviral drugs or the immune system. PGE₂ is a key modulator of active inflammation with the potential to regulate interferon signaling upon microbial invasion or viral infections. In this review, we raise the perspective of gut interkingdom interactions involving C. albicans and enteric viruses, with a special focus on biofilms, PGE₂, and viral replication. Ultimately, we discuss the possible implications of C. albicans-enteric virus associations on host immune responses, particularly the interferon signaling pathway.

Prokaryotic and viral genomes recovered from 787 Japanese gut metagenomes revealed microbial features linked to diets, populations, and diseases

We reconstructed 19,084 prokaryotic and 31,395 viral genomes from 787 Japanese gut metagenomes as Japanese metagenome-assembled genomes (JMAG) and Japanese Virus Database (JVD), which are large microbial genome datasets for a single population. Population-specific enrichment of the Bacillus subtilis and β-porphyranase among the JMAG could derive from the Japanese traditional food natto (fermented soybeans) and nori (laver), respectively. Dairy-related Enterococcus_B lactis and Streptococcus thermophilus were nominally associated with the East Asian-specific missense variant rs671:G>A in ALDH2, which was associated with dairy consumption. Of the species-level viral genome clusters in the JVD, 62.9% were novel. The β crAss-like phage composition was low among the Japanese but relatively high among African and Oceanian peoples. Evaluations of the association between crAss-like phages and diseases showed significant disease-specific associations. Our large catalog of virus-host pairs identified the positive correlation between the abundance of the viruses and their hosts.

Moderate Hyperglycemia-Preventive Effect and Mechanism of Action of Periplaneta americana Oligosaccharides in Streptozotocin-Induced Diabetic Mice

Periplaneta americana is a kind of medicinal and edible insect, and its oligosaccharides (PAOS) have been reported to exert anti-inflammatory effects by regulating immunity, reducing oxidative stress, and meliorating gut microbiota. We hypothesized PAOS might benefit experimental diabetes mellitus (DM), an inflammatory disease coordinated by both innate and adaptive immunity. This study aimed to evaluate the effect of PAOS on glycemia and its potential mechanisms. Mice model of diabetes was established, and then the potential effects of PAOS was tested in vivo. Here, we found that PAOS triggered a moderate hyperglycemia-preventive effect on DM mice, showing markedly alleviated symptoms of DM, reduced blood glucose, and meliorated functions of liver and pancreas β cell. Deciphering the underlying mechanism of PAOS-improving diabetes, the results revealed that PAOS downregulated the blood glucose level by activating PI3K/AKT/mTOR and Keap/Nrf2/HO-1 pathways, meanwhile inhibiting TLR4/MAPK/NF-κB, Beclin1/LC3, and NLRP3/caspase1 pathways in vivo. Furthermore, analyses of the microbial community intriguingly exhibited that PAOS promoted the communities of bacteria producing short-chain fatty acids (SCFAs), whereas attenuating lipopolysaccharides (LPS)-producing ones that favored inflammatory tolerance. Collectively, balancing the intestinal bacterial communities by PAOS, which favored anabolism but suppressed inflammatory responses, contributed substantially to the glycemia improvement of PAOS in DM mice. Accordingly, PAOS might function as complementary and alternative medicine for DM.

Characterization of the human gut virome in metabolic and autoimmune diseases

The intestinal microbiome is dominated by bacteria and plays a pivotal role in the occurrence and development of disease, including several metabolic and autoimmune disorders. While intestinal viral communities, primarily made up of bacteriophages, are also thought to play a role in disease pathogenesis in the gastrointestinal tract, they have received much less attention than intestinal bacteria. Thus, there is limited information about the relationship between bacteriophages and disease. This review explores a potential role for the intestinal viral microbiome in various metabolic and autoimmune diseases.

Microbial dysbiosis in the gut drives systemic autoimmune diseases

Trillions of microbes survive and thrive inside the human body. These tiny creatures are crucial to the development and maturation of our immune system and to maintain gut immune homeostasis. Microbial dysbiosis is the main driver of local inflammatory and autoimmune diseases such as colitis and inflammatory bowel diseases. Dysbiosis in the gut can also drive systemic autoimmune diseases such as type 1 diabetes, rheumatic arthritis, and multiple sclerosis. Gut microbes directly interact with the immune system by multiple mechanisms including modulation of the host microRNAs affecting gene expression at the post-transcriptional level or production of microbial metabolites that interact with cellular receptors such as TLRs and GPCRs. This interaction modulates crucial immune functions such as differentiation of lymphocytes, production of interleukins, or controlling the leakage of inflammatory molecules from the gut to the systemic circulation. In this review, we compile and analyze data to gain insights into the underpinning mechanisms mediating systemic autoimmune diseases. Understanding how gut microbes can trigger or protect from systemic autoimmune diseases is crucial to (1) tackle these diseases through diet or lifestyle modification, (2) develop new microbiome-based therapeutics such as prebiotics or probiotics, (3) identify diagnostic biomarkers to predict disease risk, and (4) observe and intervene with microbial population change with the flare-up of autoimmune responses. Considering the microbiome signature as a crucial player in systemic autoimmune diseases might hold a promise to turn these untreatable diseases into manageable or preventable ones.

Phylogenetic Diversity of Animal Oral and Gastrointestinal Viromes Useful in Surveillance of Zoonoses

Great emphasis has been placed on bacterial microbiomes in human and animal systems. In recent years, advances in metagenomics have allowed for the detection and characterization of more and more native viral particles also residing in these organisms. The digestive tracts of animals and humans—from the oral cavity, to the gut, to fecal excretions—have become one such area of interest. Next-generation sequencing and bioinformatic analyses have uncovered vast phylogenetic virome diversity in companion animals, such as dogs and cats, as well as farm animals and wildlife such as bats. Zoonotic and arthropod-borne illnesses remain major causes of worldwide outbreaks, as demonstrated by the devastating COVID-19 pandemic. This highlights the increasing need to identify and study animal viromes to prevent such disastrous cross-species transmission outbreaks in the coming years. Novel viruses have been uncovered in the viromes of multiple organisms, including birds, bats, cats, and dogs. Although the exact consequences for public health have not yet become clear, many analyses have revealed viromes dominated by RNA viruses, which can be the most problematic to human health, as these genomes are known for their high mutation rates and immune system evasion capabilities. Furthermore, in the wake of worldwide disruption from the COVID-19 pandemic, it is evident that proper surveillance of viral biodiversity is crucial. For instance, gut viral metagenomic analysis in dogs has shown close relationships between the highly abundant canine coronavirus and human coronavirus strains 229E and NL63. Future studies and vigilance could potentially save many lives.

Intestinal phages interact with bacteria and are involved in human diseases

EMBL-EBI The European Bioinformatics Institute; E. coli Escherichia coli; E. faecalis Enterobacter faecalis; B. fragilis Bacteroides fragilis; B. vulgatus Bacteroides vulgatus; SaPIs Staphylococcus aureus pathogenicity islands; ARGs Antibiotic resistance genes; STEC Shiga toxigenic E. coli; Stx Shiga toxin; BLAST Basic Local Alignment Search Tool; TSST-1 Toxic shock toxin 1; RBPs Receptor-binding proteins; LPS lipopolysaccharide; OMVs Outer membrane vesicles; PT Phosphorothioate; BREX Bacteriophage exclusion; OCR Overcome classical restriction; Pgl Phage growth limitation; DISARM Defense island system associated with restrictionmodification; R-M system Restriction-modification system; BREX system Bacteriophage exclusion system; CRISPR Clustered regularly interspaced short palindromic repeats; Cas CRISPR-associated; PAMs Prospacer adjacent motifs; crRNA CRISPR RNA; SIE; OMPs; Superinfection exclusion; Outer membrane proteins; Abi Abortive infection; TA Toxin-antitoxin; TLR Toll-like receptor; APCs Antigen-presenting cells; DSS Dextran sulfate sodium; IELs Intraepithelial lymphocytes; FMT Fecal microbiota transfer; IFN-γ Interferon-gamma; IBD Inflammatory bowel disease; AgNPs Silver nanoparticles; MDSC Myeloid-derived suppressor cell; CRC Colorectal cancer; VLPs Virus-like particles; TMP Tape measure protein; PSMB4 Proteasome subunit beta type-4; ALD Alcohol-related liver disease; GVHD Graft-versus-host disease; ROS Reactive oxygen species; RA Rheumatoid arthritis; CCP Cyclic citrullinated protein; AMGs Accessory metabolic genes; T1DM Type 1 diabetes mellitus; T2DM Type 2 diabetes mellitus; SCFAs Short-chain fatty acids; GLP-1 Glucagon-like peptide-1; A. baumannii Acinetobacter baumannii; CpG Deoxycytidylinate-phosphodeoxyguanosine; PEG Polyethylene glycol; MetS Metabolic syndrome; OprM Outer membrane porin M.

Gut virome in early life: origins and implications

The human body is colonized by a multitude of bacteria, fungi, and viruses, which play important roles in health and disease. Microbial colonization during early life is thought to be a particularly important period with lasting consequences for health. Viral populations in the gut are particularly dynamic in early life before they stabilize in adulthood. The composition of the early-life virome is increasingly recognized as a determinant of disease later in life. Here, we review the development of the virome in healthy infants, as well as the role of the early-life virome in the development of disease states including diarrhea, malnutrition, and autoimmune diseases.