The blood DNA virome in 8,000 humans

Nucleic acid degradation after long-term dried blood spot storage

Collecting and preserving biological samples in the field, particularly in remote areas in tropical forests, prior to laboratory analysis is challenging. Blood samples in many cases are used for nucleic acid-based species determination, genomics or pathogen research. In most cases, maintaining a cold chain is impossible and samples remain at ambient temperature for extended periods of time before controlled storage conditions become available. Dried blood spot (DBS) storage, blood stored on cellulose-based paper, has been widely applied to facilitate sample collection and preservation in the field for decades. However, it is unclear how long-term storage on this substrate affects nucleic acid concentration and integrity. We analysed nucleic acid quality from DBS stored on Whatman filter paper no. 3 and FTA cards for up to 15 years in comparison to cold-chain stored samples using four nucleic acid extraction methods. We examined the ability to identify viral sequences from samples of 12 free-ranging primates in the Amazon forest, using targeted hybridization capture, and determined if mitochondrial genomes could be retrieved. The results suggest that even after extended periods of storage, DBS will be suitable for some genomic applications but may be of limited use for viral pathogen research, particularly RNA viruses.

The Blood Virome: A new frontier in biomedical science

Recent advances in metagenomic testing opened a new window into the mammalian blood virome. Comprised of well-known viruses like human immunodeficiency virus, hepatitis C virus, and hepatitis B virus, the virome also includes many other eukaryotic viruses and phages whose medical significance, lifecycle, epidemiology, and impact on human health are less well known and thus regarded as commensals. This review synthesizes available information for the so-called commensal virome members that circulate in the blood of humans considering their restriction to and interaction with the human host, their natural history, and their impact on human health and physiology.

Long-Read Nanopore-Based Sequencing of Anelloviruses

Routinely used metagenomic next-generation sequencing (mNGS) techniques often fail to detect low-level viremia (<104 copies/mL) and appear biased towards viruses with linear genomes. These limitations hinder the capacity to comprehensively characterize viral infections, such as those attributed to the Anelloviridae family. These near ubiquitous non-pathogenic components of the human virome have circular single-stranded DNA genomes that vary in size from 2.0 to 3.9 kb and exhibit high genetic diversity. Hence, species identification using short reads can be challenging. Here, we introduce a rolling circle amplification (RCA)-based metagenomic sequencing protocol tailored for circular single-stranded DNA genomes, utilizing the long-read Oxford Nanopore platform. The approach was assessed by sequencing anelloviruses in plasma drawn from people who inject drugs (PWID) in two geographically distinct cohorts. We detail the methodological adjustments implemented to overcome difficulties inherent in sequencing circular genomes and describe a computational pipeline focused on anellovirus detection. We assessed our protocol across various sample dilutions and successfully differentiated anellovirus sequences in conditions simulating mixed infections. This method provides a robust framework for the comprehensive characterization of circular viruses within the human virome using the Oxford Nanopore.

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.

Plasma Virome of HIV-infected Subjects on Suppressive Antiretroviral Therapy Reveals Association of Differentially Abundant Viruses with Distinct T-cell Phenotypes and Inflammation

Background

The plasma virome represents the overall composition of viral sequences present in it. Alteration in plasma virome has been reported in treatment naïve and immunocompromised (CD4 count < 200) people with HIV (PWH). However, the effect of ART on virome composition in PWH on ART with preserved CD4 counts is poorly understood.

Objectives

We aimed to assess the alterations in plasma virome in PWH on ART in comparison to HIV-negative uninfected controls and to further investigate possible associations of plasma viruses with inflammation and immune dysfunction, namely, immunosenescence and immune exhaustion.

Methods

Plasma viral DNA from PWH on ART and controls was used for sequencing on the Illumina Nextseq500 platform, followed by the identification of viral sequences using an automated pipeline, VIROMATCH. Multiplex cytokine assay was performed to measure the concentrations of various cytokines in plasma. Immunophenotyping was performed on PBMCs to identify T cell markers of immunosenescence and immune exhaustion.

Results

In our observational, cross-sectional pilot study, chronically infected PWH on ART had significantly different viral species compositions compared to controls. The plasma virome of PWH showed a significantly high relative abundance of species Human gammaherpesvirus 4, also known as Epstein-Barr virus (EBV). Moreover, EBV emerged as a significant viral taxon differentially enriched in PWH on ART, which further correlated positively with the exhaustion phenotype of T cells and significantly increased TNF-α in PWH on ART. Additionally, a significantly increased proportion of senescent T cells and IL-8 cytokine was detected in PWH on ART.

Conclusion

Altered plasma virome influenced the inflammatory response and T-cell phenotype in PWH on ART.

Three Modes of Viral Adaption by the Heart

Viruses elicit long-term adaptive responses in the tissues they infect. Understanding viral adaptions in humans is difficult in organs such as the heart, where primary infected material is not routinely collected. In search of asymptomatic infections with accompanying host adaptions, we mined for cardio-pathogenic viruses in the unaligned reads of nearly one thousand human hearts profiled by RNA sequencing. Among virus-positive cases (~20%), we identified three robust adaptions in the host transcriptome related to inflammatory NFκB signaling and post-transcriptional regulation by the p38-MK2 pathway. The adaptions are not determined by the infecting virus, and they recur in infections of human or animal hearts and cultured cardiomyocytes. Adaptions switch states when NFκB or p38-MK2 are perturbed in cells engineered for chronic infection by the cardio-pathogenic virus, coxsackievirus B3. Stratifying viral responses into reversible adaptions adds a targetable systems-level simplification for infections of the heart and perhaps other organs.

MetaCerberus: distributed highly parallelized HMM-based processing for robust functional annotation across the tree of life

MOTIVATION

MetaCerberus is a massively parallel, fast, low memory, scalable annotation tool for inference gene function across genomes to metacommunities. MetaCerberus provides an elusive HMM/HMMER-based tool at a rapid scale with low memory. It offers scalable gene elucidation to major public databases, including KEGG (KO), COGs, CAZy, FOAM, and specific databases for viruses, including VOGs and PHROGs, from single genomes to metacommunities.

RESULTS

MetaCerberus is 1.3× as fast on a single node than eggNOG-mapper v2 on 5× less memory using an exclusively HMM/HMMER mode. In a direct comparison, MetaCerberus provides better annotation of viruses, phages, and archaeal viruses than DRAM, Prokka, or InterProScan. MetaCerberus annotates more KOs across domains when compared to DRAM, with a 186× smaller database, and with 63× less memory. MetaCerberus is fully integrated for automatic analysis of statistics and pathways using differential statistic tools (i.e. DESeq2 and edgeR), pathway enrichment (GAGE R), and pathview R. MetaCerberus provides a novel tool for unlocking the biosphere across the tree of life at scale.

AVAILABILITY AND IMPLEMENTATION

MetaCerberus is written in Python and distributed under a BSD-3 license. The source code of MetaCerberus is freely available at https://github.com/raw-lab/metacerberus compatible with Python 3 and works on both Mac OS X and Linux. MetaCerberus can also be easily installed using bioconda: mamba create -n metacerberus -c bioconda -c conda-forge metacerberus.

Pandemic preparedness: On the efficacy of non-pharmaceutical interventions in COVID-19 and about approaches to predict future pandemic viruses

With three major viral pandemics over the last 100 years, namely the Spanish flu, AIDS and COVID-19 each claiming many millions of lives, pandemic preparedness has become an important issue for public health. The economic, social and political consequences of the upheaval caused by such pandemics also represent a major challenge for governments with respect to sustainable development goals. The field of pandemic preparedness is vast and the current article can only address selected aspects. The article looks first backwards and addresses the question of the efficacy of non-pharmaceutical interventions (NPI) on the trajectory of the COVID-19 pandemic. The article looks then forward by asking to what extent viral candidates for future pandemics can be predicted by virome analyses from metagenome and transcriptome sequencing, by focusing on the virome from specific animal species and using ecological and epidemiological data about spillover viral infections in veterinary and human medicine. As a comprehensive overview on pandemic preparedness is beyond the capacity of a single reviewer, only selected topics will be discussed using recent key scientific publications. Since COVID-19 has not run its course, a computational program able to predict the future evolution of SARS-CoV-2 is mentioned that could assist proactive mRNA vaccine developments against possible future variants of concern. Ending the COVID-19 epidemic necessitates mucosal vaccines that can suppress the transmission of SARS-CoV-2 and therefore this article closes by discussing a promising and versatile protein nanoparticle experimental vaccine approach for inhalation that does not depend on needles nor a cold chain for distribution.

Early detection of active Human CytomegaloVirus (hCMV) infection in pregnant women using data generated for noninvasive fetal aneuploidy testing

BACKGROUND

Prenatal hCMV infections can lead to severe embryopathy and neurological sequelae in neonates. Screening during pregnancy is not recommended by global societies, as there is no effective therapy. Recently, several groups showed that maternal-fetal hCMV transmission can be strongly reduced by administering anti-viral agents early in pregnancy. This calls for a screening method to identify at risk pregnancies at an appropriate gestational age, with the possibility for large-scale enrolment. Non-Invasive Prenatal Testing (NIPT) for fetal aneuploidy screening early in pregnancy is already implemented in many countries and performed on a large-scale basis. We investigated the use of whole genome cell-free DNA (cfDNA) sequencing data, generated for the purpose of NIPT, as (pre-)screening tool to identify women with active hCMV-infections, eligible for therapy.

METHODS

Coded raw sequencing NIPT data from 204,818 pregnant women from three testing laboratories were analyzed for the presence of hCMV-cfDNA. Samples were stratified by cfDNA-hCMV load. For validation and interpretation, diagnostic hCMV-qPCR and serology testing were performed on a subset of cfDNA-hCMV-positive (n = 112) and -negative (n = 127) samples.

FINDINGS

In 1930 samples (0.94%) hCMV fragments were detected. Validation by hCMV-qPCR showed that samples with high cfDNA-hCMV load tested positive and cfDNA-hCMV-negative samples tested negative. In 32/112 cfDNA-hCMV-positive samples (28.6%) the serological profile suggested a recent primary infection: this was more likely in samples with high cfDNA-hCMV load (78.6%) than in samples with low cfDNA-hCMV load (11.0%). In none of the cfDNA-hCMV-negative samples serology was indicative of a recent primary infection.

INTERPRETATION

Our study shows that large-scale (pre-)screening for both genetic fetal aberrations and active maternal hCMV infections during pregnancy can be combined in one cfDNA sequencing test, performed on a single blood sample, drawn in the first trimester of pregnancy.

FUNDING

This work was partly funded by the Prenatal Screening Foundation Nijmegen, the Netherlands.

Equine herpesvirus 4 infected domestic horses associated with Sintashta spoke-wheeled chariots around 4,000 years ago

Equine viral outbreaks have disrupted the socio-economic life of past human societies up until the late 19th century and continue to be of major concern to the horse industry today. With a seroprevalence of 60-80 per cent, equine herpesvirus 4 (EHV-4) is the most common horse pathogen on the planet. Yet, its evolutionary history remains understudied. Here, we screen the sequenced data of 264 archaeological horse remains to detect the presence of EHV-4. We recover the first ancient EHV-4 genome with 4.2× average depth-of-coverage from a specimen excavated in the Southeastern Urals and dated to the Early Bronze Age period, approximately 3,900 years ago. The recovery of an EHV-4 virus outside the upper respiratory tract not only points to an animal particularly infected but also highlights the importance of post-cranial bones in pathogen characterisation. Bayesian phylogenetic reconstruction provides a minimal time estimate for EHV-4 diversification to around 4,000 years ago, a time when modern domestic horses spread across the Central Asian steppes together with spoke-wheeled Sintashta chariots, or earlier. The analyses also considerably revise the diversification time of the two EHV-4 subclades from the 16th century based solely on modern data to nearly a thousand years ago. Our study paves the way for a robust reconstruction of the history of non-human pathogens and their impact on animal health.

The virome in allergy and asthma: A nascent, ineffable player

Allergic diseases can be affected by virus-host interactions and are increasingly linked with the tissue-specific microbiome. High-throughput metagenomic sequencing has offered the opportunity to study the presence of viruses as an ecologic system, namely, the virome. Even though virome studies are technically challenging conceptually and analytically, they are already producing novel data expanding our understanding of the pathophysiologic mechanisms related to chronic inflammation and allergy. The importance of interspecies and intraspecies interactions is becoming apparent, as they can significantly, directly or indirectly, affect the host's response and antigenic state. Here, we emphasize the challenges and potential insights related to study of the virome in the context of allergy and asthma. We review the limited number of studies that have investigated the virome in these conditions, underlining the need for prospective, repeated sampling designs to unravel the virome's impact on disease development and its interplay with microbiota and immunity. The potential therapeutic use of bacteriophages, which are highly complex components of the virome, is discussed. There is clearly a need for further in-depth investigation of the virome as a system in allergic diseases.

Phenoptosis and the Various Types of Natural Selection

In the first description of evolution, the fundamental mechanism is the natural selection favoring the individuals best suited for survival and reproduction (selection at the individual level or classical Darwinian selection). However, this is a very reductive description of natural selection that does not consider or explain a long series of known phenomena, including those in which an individual sacrifices or jeopardizes his life on the basis of genetically determined mechanisms (i.e., phenoptosis). In fact, in addition to (i) selection at the individual level, it is essential to consider other types of natural selection such as those concerning: (ii) kin selection and some related forms of group selection; (iii) the interactions between the innumerable species that constitute a holobiont; (iv) the origin of the eukaryotic cell from prokaryotic organisms; (v) the origin of multicellular eukaryotic organisms from unicellular organisms; (vi) eusociality (e.g., in many species of ants, bees, termites); (vii) selection at the level of single genes, or groups of genes; (viii) the interactions between individuals (or more precisely their holobionts) of the innumerable species that make up an ecosystem. These forms of natural selection, which are all effects and not violations of the classical Darwinian selection, also show how concepts as life, species, individual, and phenoptosis are somewhat not entirely defined and somehow arbitrary. Furthermore, the idea of organisms selected on the basis of their survival and reproduction capabilities is intertwined with that of organisms also selected on the basis of their ability to cooperate and interact, even by losing their lives or their distinct identities.

Infectious disease in the Pleistocene: Old friends or old foes?

The impact of endemic and epidemic disease on humans has traditionally been seen as a comparatively recent historical phenomenon associated with the Neolithisation of human groups, an increase in population size led by sedentarism, and increasing contact with domesticated animals as well as species occupying opportunistic symbiotic and ectosymbiotic relationships with humans. The orthodox approach is that Neolithisation created the conditions for increasing population size able to support a reservoir of infectious disease sufficient to act as selective pressure. This orthodoxy is the result of an overly simplistic reliance on skeletal data assuming that no skeletal lesions equated to a healthy individual, underpinned by the assumption that hunter-gatherer groups were inherently healthy while agricultural groups acted as infectious disease reservoirs. The work of van Blerkom, Am. J. Phys. Anthropol., vol. suppl 37 (2003), Wolfe et al., Nature, vol. 447 (2007) and Houldcroft and Underdown, Am. J. Phys. Anthropol., vol. 160, (2016) has changed this landscape by arguing that humans and pathogens have long been fellow travelers. The package of infectious diseases experienced by our ancient ancestors may not be as dissimilar to modern infectious diseases as was once believed. The importance of DNA, from ancient and modern sources, to the study of the antiquity of infectious disease, and its role as a selective pressure cannot be overstated. Here we consider evidence of ancient epidemic and endemic infectious diseases with inferences from modern and ancient human and hominin DNA, and from circulating and extinct pathogen genomes. We argue that the pandemics of the past are a vital tool to unlock the weapons needed to fight pandemics of the future.

VIGA: a one-stop tool for eukaryotic virus identification and genome assembly from next-generation-sequencing data

Identification of viruses and further assembly of viral genomes from the next-generation-sequencing data are essential steps in virome studies. This study presented a one-stop tool named VIGA (available at https://github.com/viralInformatics/VIGA) for eukaryotic virus identification and genome assembly from NGS data. It was composed of four modules, namely, identification, taxonomic annotation, assembly and novel virus discovery, which integrated several third-party tools such as BLAST, Trinity, MetaCompass and RagTag. Evaluation on multiple simulated and real virome datasets showed that VIGA assembled more complete virus genomes than its competitors on both the metatranscriptomic and metagenomic data and performed well in assembling virus genomes at the strain level. Finally, VIGA was used to investigate the virome in metatranscriptomic data from the Human Microbiome Project and revealed different composition and positive rate of viromes in diseases of prediabetes, Crohn's disease and ulcerative colitis. Overall, VIGA would help much in identification and characterization of viromes, especially the known viruses, in future studies.

Immunogenicity of bacteriophages

Hundreds of trillions of diverse bacteriophages (phages) peacefully thrive within and on the human body. However, whether and how phages influence their mammalian hosts is poorly understood. In this review, we explore current knowledge and present growing evidence that direct interactions between phages and mammalian cells often induce host inflammatory and antiviral immune responses. We show evidence that, like viruses of the eukaryotic host, phages are actively internalized by host cells and activate conserved viral detection receptors. This interaction often generates proinflammatory cytokine secretion and recruitment of adaptive immune programs. However, significant variability exists in phage-immune interactions, suggesting an important role for structural phage characteristics. The factors leading to the differential immunogenicity of phages remain largely unknown but are highly influenced by their human and bacterial hosts.

SCANellome: Analysis of the Genomic Diversity of Human and Non-Human Primate Anelloviruses from Metagenomics Data

Anelloviruses are extremely prevalent in the human population and are considered to be commensal parts of the human virome. The best-known member in humans is the Torque teno virus. Recent metagenomic next-generation sequencing investigations have helped reveal the considerable number of species and genotypes from the same genus that can be co-detected within a single individual and that this diversity increases as a function of age during the first months/years of life. As a result, to date, the bioinformatics analysis of this genetic diversity remains complex and constraining for researchers. Here, we present SCANellome, a user-friendly tool to investigate the anellome composition at the genus, species, and genotype levels of samples from metagenomics data generated by the Illumina and Nanopore platforms. SCANellome is based on an in-house up-to-date database that includes all human and non-human primate anellovirus reference sequences available on GenBank and meets the latest classification criteria established by the International Committee on Taxonomy of Viruses.

Characterization of the Human Blood Virome in Iranian Multiple Transfused Patients

Blood transfusion safety is an essential element of public health. Current blood screening strategies rely on targeted techniques that could miss unknown or unexpected pathogens. Recent studies have demonstrated the presence of a viral community (virobiota/virome) in the blood of healthy individuals. Here, we characterized the blood virome in patients frequently exposed to blood transfusion by using Illumina metagenomic sequencing. The virome of these patients was compared to viruses present in healthy blood donors. A total number of 155 beta-thalassemia, 149 hemodialysis, and 100 healthy blood donors were pooled with five samples per pool. Members of the Anelloviridae and Flaviviridae family were most frequently observed. Interestingly, samples of healthy blood donors harbored traces of potentially pathogenic viruses, including adeno-, rota-, and Merkel cell polyomavirus. Viruses of the Anelloviridae family were most abundant in the blood of hemodialysis patients and displayed a higher anellovirus richness. Pegiviruses (Flaviviridae) were only observed in patient populations. An overall trend of higher eukaryotic read abundance in both patient groups was observed. This might be associated with increased exposure through blood transfusion. Overall, the findings in this study demonstrated the presence of various viruses in the blood of Iranian multiple-transfused patients and healthy blood donors.

Human Anelloviruses: Influence of Demographic Factors, Recombination, and Worldwide Diversity

Anelloviruses represent the major and most diverse component of the healthy human virome, referred to as the anellome. In this study, we determined the anellome of 50 blood donors, forming two sex- and age-matched groups. Anelloviruses were detected in 86% of the donors. The number of detected anelloviruses increased with age and was approximately twice as high in men as in women. A total of 349 complete or nearly complete genomes were classified as belonging to torque teno virus (TTV), torque teno mini virus (TTMV), and torque teno midi virus (TTMDV) anellovirus genera (197, 88, and 64 sequences, respectively). Most donors had intergenus (69.8%) or intragenus (72.1%) coinfections. Despite the limited number of sequences, intradonor recombination analysis showed 6 intragenus recombination events in ORF1. As thousands of anellovirus sequences have been described recently, we finally analyzed the global diversity of human anelloviruses. Species richness and diversity were close to saturation in each anellovirus genus. Recombination was found to be the main factor promoting diversity, although its effect was significantly lower in TTV than in TTMV and TTMDV. Overall, our results suggest that differences in diversity between genera may be caused by variations in the relative contribution of recombination. IMPORTANCE Anelloviruses are the most common human infectious viruses and are considered essentially harmless. Compared to other human viruses, they are characterized by enormous diversity, and recombination is suggested to play an important role in their diversification and evolution. Here, by analyzing the composition of the plasma anellome of 50 blood donors, we find that recombination is also a determinant of viral evolution at the intradonor level. On a larger scale, analysis of anellovirus sequences currently available in databases shows that their diversity is close to saturation and differs among the three human anellovirus genera and that recombination is the main factor explaining this intergenus variability. Global characterization of anellovirus diversity could provide clues about possible associations between certain virus variants and pathologies, as well as facilitate the implementation of unbiased PCR-based detection protocols, which may be relevant for using anelloviruses as endogenous markers of immune status.

Understanding torquetenovirus (TTV) as an immune marker

Torquetenovirus (TTV), a small, single stranded anellovirus, is currently being explored as a marker of immunocompetence in patients with immunological impairment and inflammatory disorders. TTV has an extremely high prevalence and is regarded as a part of the human virome, the replication of which is controlled by a functioning immune system. The viral load of TTV in plasma of individuals is thought to reflect the degree of immunosuppression. Measuring and quantifying this viral load is especially promising in organ transplantation, as many studies have shown a strong correlation between high TTV loads and increased risk of infection on one side, and low TTV loads and an increased risk of rejection on the other side. As clinical studies are underway, investigating if TTV viral load measurement is superior for gauging antirejection therapy compared to medication-levels, some aspects nevertheless have to be considered. In contrast with medication levels, TTV loads have to be interpreted bearing in mind that viruses have properties including transmission, tropism, genotypes and mutations. This narrative review describes the potential pitfalls of TTV measurement in the follow-up of solid organ transplant recipients and addresses the questions which remain to be answered.

T cell immune deficiency rather than chromosome instability predisposes patients with short telomere syndromes to squamous cancers

Patients with short telomere syndromes (STS) are predisposed to developing cancer, believed to stem from chromosome instability in neoplastic cells. We tested this hypothesis in a large cohort assembled over the last 20 years. We found that the only solid cancers to which patients with STS are predisposed are squamous cell carcinomas of the head and neck, anus, or skin, a spectrum reminiscent of cancers seen in patients with immunodeficiency. Whole-genome sequencing showed no increase in chromosome instability, such as translocations or chromothripsis. Moreover, STS-associated cancers acquired telomere maintenance mechanisms, including telomerase reverse transcriptase (TERT) promoter mutations. A detailed study of the immune status of patients with STS revealed a striking T cell immunodeficiency at the time of cancer diagnosis. A similar immunodeficiency that impaired tumor surveillance was documented in mice with short telomeres. We conclude that STS patients’ predisposition to solid cancers is due to T cell exhaustion rather than autonomous defects in the neoplastic cells themselves.

Longitudinal transkingdom gut microbial approach towards decompensation in outpatients with cirrhosis

OBJECTIVE

First decompensation development is a critical milestone that needs to be predicted. Transkingdom gut microbial interactions, including archaeal methanogens, may be important targets and predictors but a longitudinal approach is needed.

DESIGN

Cirrhosis outpatients who provided stool twice were included. Group 1: compensated, group 2: 1 decompensation (decomp), group 3: >1 decompensationwere followed and divided into those who remained stable or decompensated. Bacteria, viral and archaeal presence, α/β diversity and taxa changes over time adjusted for clinical variables were analysed. Correlation networks between kingdoms were analysed.

RESULTS

157 outpatients (72 group 1, 33 group 2 and 52 group 3) were followed and 28%-47% developed outcomes. Baseline between those who remained stable/developed outcome: While no α/β diversity differences were seen, commensals were lower and pathobionts were higher in those who decompensated. After decompensation: those experiencing their first decompensation showed greater decrease in α/β-diversity, bacterial change (↑Lactobacillus spp, Streptococcus parasanguinis and ↓ beneficial Lachnospiraceae and Eubacterium hallii) and viral change (↑Siphoviridae, ↓ Myoviridae) versus those with further decompensation. Archaea: 19% had Methanobacter brevii, which was similar between/within groups. Correlation networks: Baseline archaeal-viral-bacterial networks were denser and more homogeneous in those who decompensated versus the rest. Archaea-bacterial correlations collapsed post first decompensation. Lactobacillus phage Lc Nu and C2-like viruses were negatively linked with beneficial bacteria.

CONCLUSION

In this longitudinal study of cirrhosis outpatients, the greatest transkingdom gut microbial changes were seen in those reaching the first decompensation, compared with subsequent decompensating events. A transkingdom approach may refine prediction and provide therapeutic targets to prevent cirrhosis progression.

The persistence and stabilization of auxiliary genes in the human skin virome

BACKGROUND

The human skin contains a diverse microbiome that provides protective functions against environmental pathogens. Studies have demonstrated that bacteriophages modulate bacterial community composition and facilitate the transfer of host-specific genes, potentially influencing host cellular functions. However, little is known about the human skin virome and its role in human health. Especially, how viral-host relationships influence skin microbiome structure and function is poorly understood.

RESULTS

Population dynamics and genetic diversity of bacteriophage communities in viral metagenomic data collected from three anatomical skin locations from 60 subjects at five different time points revealed that cutaneous bacteriophage populations are mainly composed of tailed Caudovirales phages that carry auxiliary genes to help improve metabolic remodeling to increase bacterial host fitness through antimicrobial resistance. Sequence variation in the MRSA associated antimicrobial resistance gene, erm(C) was evaluated using targeted sequencing to further confirm the presence of antimicrobial resistance genes in the human virome and to demonstrate how functionality of such genes may influence persistence and in turn stabilization of bacterial host and their functions.

CONCLUSIONS

This large temporal study of human skin associated viruses indicates that the human skin virome is associated with auxiliary metabolic genes and antimicrobial resistance genes to help increase bacterial host fitness.

Comprehensive analysis of circulating viral DNA in maternal plasma at population-scale using low-pass whole-genome sequencing

As the most readily adopted molecular screening test, low-pass WGS of maternal plasma cell-free DNA for aneuploidy detection generates a vast amount of genomic data. This large-scale method also allows for high-throughput virome screening. NIPT sequencing data, yielding 6.57 terabases of data from 187.8 billion reads, from 12,951 pregnant Turkish women was used to investigate the prevalence and abundance of viral DNA in plasma. Among the 22 virus sequences identified in 12% of participants were human papillomavirus, herpesvirus, betaherpesvirus and anellovirus. We observed a unique pattern of circulating viral DNA with a high prevalence of papillomaviruses. The prevalence of herpesviruses/anellovirus was similar among Turkish, European and Dutch populations. Hepatitis B prevalence was remarkably low in Dutch, European and Turkish populations, but higher in China. WGS data revealed that herpesvirus/anelloviruses are naturally found in European populations. This represents the first comprehensive research on the plasma virome of pregnant Turkish women.

Clinical Diagnosis Application of Metagenomic Next-Generation Sequencing of Plasma in Suspected Sepsis

Purpose

We analyzed the clinical concordance of mNGS test results from blood samples and improved the clinical efficiency of mNGS in the diagnosis of suspected sepsis pathogens.

Patients and Methods

In this study, 99 samples of suspected blood flow infection were included for plasma mNGS, and the correlation between mNGS results and blood culture results, serum inflammatory indices, clinical symptoms and antibiotic treatment was analyzed, as well as the comparison with the detection rate of BALF pathogens, as well as the classification of different pathogens in the mNGS results were analyzed.

Results

The mNGS pathogen detection rate was higher than that of traditional blood culture (83.02% vs 35.82%). The rate of the mNGS results being consistent with the clinical diagnosis was also higher than that of traditional blood culture (58.49% vs 20.75%). This study shows that bacteria and fungi are the main pathogens in sepsis, and viral sepsis is very rare. In this study, 32% of sepsis patients were secondary to pneumonia. Compared with the pathogen detection rate using alveolar lavage fluid, the detection rate from plasma mNGS was 62.5%. Samples were also easy to sample, noninvasive, and more convenient for clinical application.

Conclusion

This study shows that compared with blood culture, the detection rate of mNGS pathogen that meets the diagnosis of sepsis is higher. We need a combination of multiple indicators to monitor the early diagnosis and treatment of sepsis.

The plasma virome in longitudinal samples from pregnant patients

Introduction

Nucleic acid from viruses is common in peripheral blood, even in asymptomatic individuals. How physiologic changes of pregnancy impact host-virus dynamics for acute, chronic, and latent viral infections is not well described. Previously we found higher viral diversity in the vagina during pregnancy associated with preterm birth (PTB) and Black race. We hypothesized that higher diversity and viral copy numbers in the plasma would show similar trends.

Methods

To test this hypothesis, we evaluated longitudinally collected plasma samples from 23 pregnant patients (11 term and 12 preterm) using metagenomic sequencing with ViroCap enrichment to enhance virus detection. Sequence data were analyzed with the ViroMatch pipeline.

Results

We detected nucleic acid from at least 1 virus in at least 1 sample from 87% (20/23) of the maternal subjects. The viruses represented 5 families: Herpesviridae, Poxviridae, Papillomaviridae, Anelloviridae, and Flaviviridae. We analyzed cord plasma from 18 of the babies from those patients and found nucleic acid from viruses in 33% of the samples (6/18) from 3 families: Herpesviridae, Papillomaviridae, and Anelloviridae. Some viral genomes were found in both maternal plasma and cord plasma from maternal-fetal pairs (e.g. cytomegalovirus, anellovirus). We found that Black race associated with higher viral richness (number of different viruses detected) in the maternal blood samples (P=0.003), consistent with our previous observations in vaginal samples. We did not detect associations between viral richness and PTB or the trimester of sampling. We then examined anelloviruses, a group of viruses that is ubiquitous and whose viral copy numbers fluctuate with immunological state. We tested anellovirus copy numbers in plasma from 63 pregnant patients sampled longitudinally using qPCR. Black race associated with higher anellovirus positivity (P<0.001) but not copy numbers (P=0.1). Anellovirus positivity and copy numbers were higher in the PTB group compared to the term group (P<0.01, P=0.003, respectively). Interestingly, these features did not occur at the time of delivery but appeared earlier in pregnancy, suggesting that although anelloviruses were biomarkers for PTB they were not triggering parturition.

Discussion

These results emphasize the importance of longitudinal sampling and diverse cohorts in studies of virome dynamics during pregnancy.

Merkel cell polyomavirus (MCPyV) DNA prevalence in Brazilian blood donors

Merkel cell polyomavirus (MCPyV) is an oncogenic virus that has been etiologically linked to Merkel cell carcinoma. Low levels of MCPyV DNA have been detected in blood donors with unclear impact on transfusion. The prevalence of MCPyV DNA in Brazilian blood donors is unclear. Therefore, the objective of this study was to evaluate the MCPyV DNA prevalence among Brazilian blood donors. We examined the presence of MCPyV DNA by real-time PCR (qPCR) in a total of 450 serum samples obtained from blood donors from three Brazilian regions (North, Central-West and South). The overall estimated MCPyV DNA prevalence was 1.1% (CI = 95%, 0.16-2.06%). Divided by region, in North Brazil (city of Macapa, state of Amapá) and South Brazil (city of Santa Maria, state of Rio Grande do Sul), the MCPyV prevalence was the same: 1.33% (CI = 95%, range 0.0-3.14%). In Central-West Brazil (city of Brasilia), the MCPyV prevalence was 0.6% (CI = 95%, 0.0-1.96%). All MCPyV positive samples showed a high cycle threshold (median Ct = 35.5), most probably related to the low viral load. More studies are necessary to unveil the impact of this oncogenic virus on transfusion medicine and if such exists, especially in regards of its infectivity and transmission potential.

Hepatitis C and HIV detection by blood RNA-sequencing in cohort of smokers

Detection of viruses by RNA and DNA sequencing has improved the understanding of the human virome. We sought to identify blood viral signatures through secondary use of RNA-sequencing (RNA-seq) data in a large study cohort. The ability to reveal undiagnosed infections with public health implications among study subjects with available sequencing data could enable epidemiologic surveys and may lead to diagnosis and therapeutic interventions, leveraging existing research data in a clinical context. We detected viral RNA in peripheral blood RNA-seq data from a COPD-enriched population of current and former smokers. Correlation between viral detection and both reported infections and relevant disease outcomes was evaluated. We identified Hepatitis C virus RNA in 228 subjects and HIV RNA in 30 subjects. Overall, we observed 31 viral species, including Epstein-Barr virus and Cytomegalovirus. We observed an enrichment of Hepatitis C and HIV infections among subjects reporting liver disease and HIV infections, respectively. Higher interferon expression scores were observed in the subjects with Hepatitis C and HIV infections. Through secondary use of RNA-seq from a cohort of current and former smokers, we detected peripheral blood viral signatures. We identified HIV and Hepatitis C virus (HCV), highlighting potential public health implications for the approach described this study. We observed correlations with reported infections, chronic infection outcomes and the host transcriptomic response, providing evidence to support the validity of the approach.

Virome Analysis and Association of Positive Coxsackievirus B Serology during Pregnancy with Congenital Heart Disease

BACKGROUND

We have previously shown coxsackievirus B (CVB) to be a potent inducer of congenital heart disease (CHD) in mice. The clinical relevance of these findings in humans and the roles of other viruses in the pathogenesis of CHD remain unknown.

METHODS

We obtained plasma samples, collected at all trimesters, from 89 subjects (104 pregnancies), 73 healthy controls (88 pregnancies), and 16 with CHD-affected birth (16 pregnancies), from the Perinatal Family Tissue Bank (PFTB). We performed CVB IgG/IgM serological assays on plasma. We also used ViroCap sequencing and PCR to test for viral nucleic acid in plasma, circulating leukocytes from the buffy coat, and in the media of a co-culture system.

RESULTS

CVB IgG/IgM results indicated that prior exposure was 7.8 times more common in the CHD group (95% CI, 1.14-54.24, adj. p-value = 0.036). However, the CVB viral genome was not detected in plasma, buffy coat, or co-culture supernatant by molecular assays, although other viruses were detected.

CONCLUSION

Detection of viral nucleic acid in plasma was infrequent and specifically no CVB genome was detected. However, serology demonstrated that prior CVB exposure is higher in CHD-affected pregnancies. Further studies are warranted to understand the magnitude of the contribution of the maternal blood virome to the pathogenesis of CHD.

Virsearcher: Identifying Bacteriophages from Metagenomes by Combining Convolutional Neural Network and Gene Information

Metagenome sequencing provides an unprecedented opportunity for the discovery of unknown microbes and viruses. A large number of phages and prokaryotes are mixed together in metagenomes. To study the influence of phages on human bodies and environments, it is of great significance to isolate phages from metagenomes. However, it is difficult to identify novel phages because of the diversity of their sequences and the frequent presence of short contigs in metagenomes. Here, virSearcher is developed to identify phages from metagenomes by combining the convolutional neural network (CNN) and the gene information of input sequences. Firstly, an input sequence is encoded in accordance with the different functions of its coding and the non-coding regions and then is converted into word embedding code through a word embedding layer before a convolutional layer. Meanwhile, the hit ratio of the virus genes is combined with the output of the CNN to further improve the performance of the network. The genes used by virSearcher consist of complete and incomplete genes. Experiments on several metagenomes have showed that, compared with others, virSearcher can significantly improve the performance for the identification of short sequences, while maintaining the performance for long ones. The source code of virSearcher is freely available from http://github.com/DrJackson18/virSearcher.

Absence of pathogenic viruses in COVID-19 convalescent plasma

BACKGROUND

It is important to maintain the safety of blood products by avoiding the transfusion of units with known and novel viral pathogens. It is unknown whether COVID-19 convalescent plasma (CCP) may contain pathogenic viruses (either newly acquired or reactivated) that are not routinely screened for by blood centers.

METHODS

The DNA virome was characterized in potential CCP donors (n = 30) using viral genome specific PCR primers to identify DNA plasma virome members of the Herpesviridae [Epstein Barr Virus (EBV), cytomegalovirus (CMV), human herpesvirus 6A/B, human herpesvirus 7] and Anelloviridae [Torque teno viruses (TTV), Torque teno mini viruses (TTMV), and Torque teno midi viruses (TTMDV)] families. In addition, the RNA plasma virome was characterized using unbiased metagenomic sequencing. Sequencing was done on a HiSeq2500 using high output mode with a read length of 2X100 bp. The sequencing reads were taxonomically classified using Kraken2. CMV and EBV seroprevalence were evaluated using a chemiluminescent immunoassay.

RESULTS

TTV and TTMDV were detected in 12 (40%) and 4 (13%) of the 30 study participants, respectively; TTMDV was always associated with infection with TTV. We did not observe TTMV DNAemia. Despite CMV and EBV seroprevalences of 33.3% and 93.3%, respectively, we did not detect Herpesviridae DNA among the study participants. Metagenomic sequencing did not reveal any human RNA viruses in CCP, including no evidence of circulating SARS-CoV-2.

DISCUSSION

There was no evidence of pathogenic viruses, whether newly acquired or reactivated, in CCP despite the presence of non-pathogenic Anelloviridae. These results confirm the growing safety data supporting CCP.

Metagenomic analysis of viral genes integrated in whole genome sequencing data of Thai patients with Brugada syndrome

Brugada syndrome (BS) is an autosomal dominant inheritance cardiac arrhythmia disorder associated with sudden death in young adults. Thailand has the highest prevalence of BS worldwide, and over 60% of patients with BS still have unclear disease etiology. Here, we performeda new viral metagenome analysis pipeline called VIRIN and validated it with whole genome sequencing (WGS) data of HeLa cell lines and hepatocellular carcinoma. Then the VIRIN pipelinewas applied to identify viral integration positions from unmapped WGS data of Thai males, including 100 BS patients (case) and 100 controls. Even though the sample preparation had noviral enrichment step, we can identify several virus genes from our analysis pipeline. The predominance of human endogenous retrovirus K (HERV-K) viruses was found in both cases andcontrols by blastn and blastx analysis. This study is the first report on the full-length HERV-Kassembled genomes in the Thai population. Furthermore, the HERV-K integration breakpointpositions were validated and compared between the case and control datasets. Interestingly,Brugada cases contained HERV-K integration breakpoints at promoters five times more oftenthan controls. Overall, the highlight of this study is the BS-specific HERV-K breakpoint positionsthat were found at the gene coding region "NBPF11" (n = 9), "NBPF12" (n = 8) and longnon-coding RNA (lncRNA) "PCAT14" (n = 4) region. The genes and the lncRNA have been reported to be associated with congenital heart and arterial diseases. These findings provide another aspect of the BS etiology associated with viral genome integrations within the humangenome.

Transmission dynamics of human herpesvirus 6A, 6B and 7 from whole genome sequences of families

While hundreds of thousands of human whole genome sequences (WGS) have been collected in the effort to better understand genetic determinants of disease, these whole genome sequences have less frequently been used to study another major determinant of human health: the human virome. Using the unmapped reads from WGS of over 1000 families, we present insights into the human blood DNA virome, focusing particularly on human herpesvirus (HHV) 6A, 6B, and 7. In addition to extensively cataloguing the viruses detected in WGS of human whole blood and lymphoblastoid cell lines, we use the family structure of our dataset to show that household drives transmission of several viruses, and identify the Mendelian inheritance patterns characteristic of inherited chromsomally integrated human herpesvirus 6 (iciHHV-6). Consistent with prior studies, we find that 0.6% of our dataset's population has iciHHV, and we locate candidate integration sequences for these cases. We document genetic diversity within exogenous and integrated HHV species and within integration sites of HHV-6. Finally, in the first observation of its kind, we present evidence that suggests widespread de novo HHV-6B integration and HHV-7 integration and reactivation in lymphoblastoid cell lines. These findings show that the unmapped read space of WGS is a promising source of data for virology research.

Impact of HIV infection and integrase strand transfer inhibitors-based treatment on the gut virome

Viruses are the most abundant components of the human gut microbiome with a significant impact on health and disease. The effects of human immunodeficiency virus (HIV) infection on gut virome has been scarcely analysed. Several studies suggested that integrase strand transfers inhibitors (INSTIs) are associated with a healthier gut. Thus, the objective of this work was to evaluate the effects of HIV infection and INSTIs on gut virome composition. 26 non-HIV-infected volunteers, 15 naive HIV-infected patients and 15 INSTIs-treated HIV-infected patients were recruited and their gut virome composition was analysed using shotgun sequencing. Bacteriophages were the most abundant and diverse viruses present in gut. HIV infection was accompanied by a decrease in phage richness which was reverted after INSTIs-based treatment. β-diversity of phages revealed that samples from HIV-infected patients clustered separately from those belonging to the control group. Differential abundant analysis showed an increase in phages belonging to Caudoviricetes class in the naive group and a decrease of Malgrandaviricetes class phages in the INSTIs-treated group compared to the control group. Besides, it was observed that INSTIs-based treatment was not able to reverse the increase of lysogenic phages associated with HIV infection or to modify the decrease observed on the relative abundance of Proteobacteria-infecting phages. Our study describes for the first time the impact of HIV and INSTIs on gut virome and demonstrates that INSTIs-based treatments are able to partially restore gut dysbiosis at the viral level, which opens several opportunities for new studies focused on microbiota-based therapies.

Epidemiology of Merkel Cell Polyomavirus Infection and Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) is a ubiquitous virus replicating in human dermal fibroblasts. MCPyV DNA can be detected on healthy skin in 67−90% of various body sites, and intact virions are regularly shed from the skin. Infection occurs early in life, and seropositivity increases from 37 to 42% in 1- to 6-year-olds to 92% in adults. Merkel cell carcinoma (MCC) is a rare but very aggressive neuroendocrine tumor of the skin. It develops mainly on sun-exposed areas as a fast-growing, reddish nodule. Two MCC entities exist: about 80% of MCC are MCPyV-associated. Tumorigenesis is driven by viral integration into the host genome and MCPyV oncogene expression. In MCPyV-negative MCC, UV radiation causes extensive DNA damage leading to the deregulation of the cell cycle. In recent decades, MCC incidence rates have increased worldwide, e.g., in the United States, from 0.15 in 1986 to 0.7/100,000 in 2016. Risk factors for the development of MCC include male sex, older age (>75 years), fair skin, intense UV exposure, and immunosuppression. Projections suggest that due to aging populations, an increase in immunosuppressed patients, and enhanced UV exposure, MCC incidence rates will continue to rise. Early diagnosis and prompt treatment are crucial to reducing high MCC morbidity and mortality.

Development of an in vitro homeostasis model between airway epithelial cells, bacteria and bacteriophages: a time-lapsed observation of cell viability and inflammatory response

Bacteriophages represent the most extensive group of viruses within the human virome and have a significant impact on general health and well-being by regulating bacterial population dynamics. Staphylococcus aureus, found in the anterior nostrils, throat and skin, is an opportunistic pathobiont that can cause a wide range of diseases, from chronic inflammation to severe and acute infections. In this study, we developed a human cell-based homeostasis model between a clinically isolated strain of S. aureus 141 and active phages for this strain (PYO^Sa141) isolated from the commercial Pyophage cocktail (PYO). The cocktail is produced by Eliava BioPreparations Ltd. (Tbilisi, Georgia) and is used as an add-on therapy for bacterial infections, mainly in Georgia. The triptych interaction model was evaluated by time-dependent analysis of cell death and inflammatory response of the nasal and bronchial epithelial cells. Inflammatory mediators (IL-8, CCL5/RANTES, IL-6 and IL-1β) in the culture supernatants were measured by enzyme-linked immunosorbent assay and cell viability was determined by crystal violet staining. By measuring trans-epithelial electrical resistance, we assessed the epithelial integrity of nasal cells that had differentiated under air-liquid interface conditions. PYO^Sa141 was found to have a prophylactic effect on airway epithelial cells exposed to S. aureus 141 by effectively down-regulating bacterial-induced inflammation, cell death and epithelial barrier disruption in a time-dependent manner. Overall, the proposed model represents an advance in the way multi-component biological systems can be simulated in vitro.

Association of plasma microbial composition with a leaky gut in obesity-related osteoarthritis: An exploratory study

Objective

To examine the plasma microbiome for differences between obese individuals with and without osteoarthritis (OA) and its association with serum lipopolysaccharide (LPS).

Design

Blood samples from 70 participants with body mass index (BMI) ​≥ ​30kg/m2 and age ≥55 years, with (cases) or without (controls) hand plus knee OA, were analyzed for serum LPS and composition of the plasma microbiome. The Dirichlet-multinominal recursive partitioning model (DM-RPart) was applied to microbiome compositional data to test the hypothesis that LPS levels distinguish plasma microbiome, accounting for BMI and age.

Results

No significant differences in alpha diversity, or compositional differences between groups at the genus level, were seen between cases and controls (p ​= ​0.11). β-Diversity was significantly associated with serum LPS levels (p ​= ​0.01). DM-RPart resulted in an optimal tree with 3 divisions: 1) based on age (split at 69 years); 2) those older than 69 were split based on BMI; 3) those with BMI <39 ​kg/m2 were split based on LPS level (at 65 EU/ml). This resulted in 4 groups (nodes 2, and 5-7). Participants in node 2 were younger and the majority had no or mild OA. Those in nodes 5 and 6 were comparable in age and BMI but node 6 had higher LPS and more severe OA. Individuals in node 7 were older, had higher BMI, and the most severe OA.

Conclusions

Our results suggest a relationship between serum LPS and the plasma microbiome in a subgroup of obese individuals with hand plus knee OA that could reflect differences in intestinal permeability.

Product-safety considerations in allogeneic chimeric antigen-receptor T-cell process flows

Allogeneic chimeric antigen-receptor T-cell process flows comprise large-scale primary cultures incorporating traditional biologics processing steps such as cell expansion, with novel processing steps such as electroporation. In addition, these process flows begin with donor-derived peripheral blood mononuclear cells and generate single batches of product, which may be used to treat hundreds of patients. The corresponding unit operation-process safety considerations are individually diverse, and in combination are currently unique and rapidly evolving. The use of available regulations and the principles of quality by design are useful in designing appropriate control strategies into the process during development to ensure process safety.

[These viruses that inhabit and visit us: The human virome]

Recent advances in new sequencing technologies have opened the way to the deciphering of human virome. So far, human virome is defined as the complete list of viruses found in human body. Those viruses could be endogenous, prokaryotic, archaeal and eukaryotic. In addition, each compartment of the human body constitutes a different microenvironment with its own virome. Viral infections can be categorized according to the outcome of the acute phase and until recently, only symptomatic and pathological infections were studied. It is now well established that a healthy person has an extremely diverse virome. This review summarizes the current state of our knowledge and also proposes another classification of the human virome based on principles of ecology.

The evolving role of liquid biopsy in lung cancer

Liquid biopsy has revolutionized the management of cancer patients. In particular, liquid biopsy-based testing has proven to be highly beneficial for identifying actionable cancer markers, especially when solid tissue biopsies are insufficient or unattainable. Beyond the predictive role, liquid biopsy may be a useful tool for comprehensive tumor genotyping, identification of emergent resistance mechanisms, monitoring of minimal residual disease, early detection, and cancer interception. The application of next generation sequencing to liquid biopsy has led to the "quantum leap" of predictive molecular pathology. Here, we review the evolving role of liquid biopsy in lung cancer.

Integrated Immunologic Monitoring in Solid Organ Transplantation: The Road Toward Torque Teno Virus-guided Immunosuppression

Potent immunosuppressive drugs have been introduced into clinical care for solid organ transplant recipients. It is now time to guide these drugs on an individual level to optimize their efficacy. An ideal tool simultaneously detects overimmunosuppression and underimmunosuppression, is highly standardized, and is straightforward to implement into routine. Randomized controlled interventional trials are crucial to demonstrate clinical value. To date, proposed assays have mainly focused on the prediction of rejection and were based on the assessment of few immune compartments. Recently, novel tools have been introduced based on a more integrated approach to characterize the immune function and cover a broader spectrum of the immune system. In this respect, the quantification of the plasma load of a highly prevalent and apathogenic virus that might reflect the immune function of its host has been proposed: the torque teno virus (TTV). Although TTV control is driven by T cells, other major immune compartments might contribute to the hosts' response. A standardized in-house polymerase chain reaction and a conformité européenne-certified commercially available polymerase chain reaction are available for TTV quantification. TTV load is associated with rejection and infection in solid organ transplant recipients, and cutoff values for risk stratification of such events have been proposed for lung and kidney transplantation. Test performance of TTV load does not allow for the diagnosis of rejection and infection but is able to define at-risk patients. Hitherto TTV load has not been used in interventional settings, but two interventional randomized controlled trials are currently testing the safety and efficacy of TTV-guided immunosuppression.

Unraveling the viral dark matter through viral metagenomics

Viruses are part of the microbiome and have essential roles in immunology, evolution, biogeochemical cycles, health, and disease progression. Viruses influence a wide variety of systems and processes, and the continued discovery of novel viruses is anticipated to reveal new mechanisms influencing the biology of diverse environments. While the identity and roles of viruses continue to be discovered and understood through viral metagenomics, most of the sequences in virome datasets cannot be attributed to known viruses or may be only distantly related to species already described in public sequence databases, at best. Such viruses are known as the viral dark matter. Ongoing discoveries from the viral dark matter have provided insights into novel viruses from a variety of environments, as well as their potential in immunological processes, virus evolution, health, disease, therapeutics, and surveillance. Increased understanding of the viral dark matter will continue with a combination of cultivation, microscopy, sequencing, and bioinformatic efforts, which are discussed in the present review.

Peripheral Blood Microbiome Analysis via Noninvasive Prenatal Testing Reveals the Complexity of Circulating Microbial Cell-Free DNA

While circulating cell-free DNA (cfDNA) is becoming a powerful marker for noninvasive identification of infectious pathogens in liquid biopsy specimens, a microbial cfDNA baseline in healthy individuals is urgently needed for the proper interpretation of microbial cfDNA sequencing results in clinical metagenomics. Because noninvasive prenatal testing (NIPT) shares many similarities with the sequencing protocol of metagenomics, we utilized the standard low-pass whole-genome-sequencing-based NIPT to establish a microbial cfDNA baseline in healthy people. Sequencing data from a total of 107,763 peripheral blood samples of healthy pregnant women undergoing NIPT screening were retrospectively collected and reanalyzed for microbiome DNA screening. It was found that more than 95% of exogenous cfDNA was from bacteria, 3% from eukaryotes, and 0.4% from viruses, indicating the gut/environment origins of many microorganisms. Overall and regional abundance patterns were well illustrated, with huge regional diversity and complexity, and unique interspecies and symbiotic relationships were observed for TORCH organisms (Toxoplasma gondii, others [Treponema pallidum {causing syphilis}, hepatitis B virus {HBV}, and human parvovirus B19 {HPV-B19}], rubella virus, cytomegalovirus [CMV], and herpes simplex virus [HSV]) and another common virus, Epstein-Barr virus (EBV). To sum up, our study revealed the complexity of the baseline circulating microbial cfDNA and showed that microbial cfDNA sequencing results need to be interpreted in a more comprehensive manner. IMPORTANCE While circulating cell-free DNA (cfDNA) has been becoming a powerful marker for noninvasive identification of infectious pathogens in liquid biopsy specimens, a baseline for microbial cfDNA in healthy individuals is urgently needed for the proper interpretation of microbial cfDNA sequencing results in clinical metagenomics. Standard low-pass whole-genome-sequencing-based NIPT shares many similarities with the sequencing protocol for metagenomics and could provide a microbial cfDNA baseline in healthy people; thus, a reference cfDNA data set of the human microbiome was established with sequencing data from a total of 107,763 peripheral blood samples of healthy pregnant women undergoing NIPT screening. Our study revealed the complexity of circulating microbial cfDNA and indicated that microbial cfDNA sequencing results need to be interpreted in a more comprehensive manner, especially with regard to geographic patterns and coexistence networks.

Plasma Virome Reveals Blooms and Transmission of Anellovirus in Intravenous Drug Users with HIV-1, HCV, and/or HBV Infections

Intravenous drug users (IDUs) are a high-risk group for HIV-1, hepatitis C virus (HCV), and hepatitis B virus (HBV) infections, which are the leading causes of death in IDUs. However, the plasma virome of IDUs and how it is influenced by above viral infections remain unclear. Using viral metagenomics, we determined the plasma virome of IDUs and its association with HIV-1, HCV, and/or HBV infections. Compared with healthy individuals, IDUs especially those with major viral infections had higher viral abundance and diversity. Anelloviridae dominated plasma virome. Coinfections of multiple anelloviruses were common, and anelloviruses from the same genus tended to coexist together. In this study, 4,487 anellovirus ORF1 sequences were identified, including 1,620 (36.1%) with less than 69% identity to any known sequences, which tripled the current number. Compared with healthy controls (HC), more anellovirus sequences were observed in neg-IDUs, and HIV-1, HCV, and/or HBV infections further expanded the sequence number in IDUs, which was characterized by the emergence of novel divergent taxons and blooms of resident anelloviruses. Pegivirus was mainly identified in infected IDUs. Five main pegivirus transmission clusters (TCs) were identified by phylogenetic analysis, suggesting a transmission link. Similar anellovirus profiles were observed in IDUs within the same TC, suggesting transmission of anellome among IDUs. Our data suggested that IDUs suffered higher plasma viral burden especially anelloviruses, which was associated with HIV-1, HCV, and/or HBV infections. Blooms in abundance and unprecedented diversity of anellovirus highlighted active evolution and replication of this virus in blood circulation, and an uncharacterized role it may engage with the host.

IMPORTANCE Virome is associated with immune status and determines or influences disease progression through both pathogenic and resident viruses. Increased viral burden in IDUs especially those with major viral infections indicated the suboptimal immune status and high infection risks of these population. Blooms in abundance and unprecedented diversity of anellovirus highlighted its active evolution and replication in the blood circulation, and sensitive response to other viral infections. In addition, transmission cluster analysis revealed the transmission link of pegivirus among IDUs, and the individuals with transmission links shared similar anellome profiles. In-depth monitoring of the plasma virome in high-risk populations is not only needed for surveillance for emerging viruses and transmission networks of major and neglected bloodborne viruses, but also important for a better understanding of commensal viruses and their role it may engage with immune system.

The human "contaminome": bacterial, viral, and computational contamination in whole genome sequences from 1000 families

The unmapped readspace of whole genome sequencing data tends to be large but is often ignored. We posit that it contains valuable signals of both human infection and contamination. Using unmapped and poorly aligned reads from whole genome sequences (WGS) of over 1000 families and nearly 5000 individuals, we present insights into common viral, bacterial, and computational contamination that plague whole genome sequencing studies. We present several notable results: (1) In addition to known contaminants such as Epstein-Barr virus and phiX, sequences from whole blood and lymphocyte cell lines contain many other contaminants, likely originating from storage, prep, and sequencing pipelines. (2) Sequencing plate and biological sample source of a sample strongly influence contamination profile. And, (3) Y-chromosome fragments not on the human reference genome commonly mismap to bacterial reference genomes. Both experiment-derived and computational contamination is prominent in next-generation sequencing data. Such contamination can compromise results from WGS as well as metagenomics studies, and standard protocols for identifying and removing contamination should be developed to ensure the fidelity of sequencing-based studies.

Diversity and Long-Term Dynamics of Human Blood Anelloviruses

Anelloviruses (AVs) are commensal members of the human blood virome. Even though it was estimated that over 90% of the human population carries AVs, the dynamics of the AV virome (“anellome”) are unknown. We investigated the dynamics of blood anellomes in two healthy people followed up for more than 30 years. Both subjects were positive for AVs in the majority of samples. Alphatorquevirus (torque teno virus [TTV]) was the most common genus in both subjects, followed by Betatorquevirus (torque teno minivirus [TTMV]) and Gammatorquevirus (torque teno midivirus [TTMDV]). Almost five times more lineages were found in subject 1 than in subject 2, and the anellomes differed phylogenetically. Both anellomes remained compositionally stable, and 9 out of 64 AV lineages were detected in over half of the time points. We confirmed the long-term and short-term persistence of 13 lineages by specific quantitative PCR (qPCR). AV lineages were detected in blood for over 30 years. Noticeable differences in anellome richness were found between the tested subjects, but both anellomes remained compositionally stable over time. These findings demonstrate that the human blood anellome is personal and that AV infection is chronic and potentially commensal.

IMPORTANCE Knowledge of the persistence of AVs in humans is crucial to our understanding of the nature of AV infection (chronic or acute) and the role of AV in the host. We therefore investigated the dynamics of anellovirus infection in two healthy people followed up for 30 years. Our findings suggest that the human blood anellovirus virome (anellome) remains stable and personal for decades.

An atlas of human viruses provides new insights into diversity and tissue tropism of human viruses

MOTIVATION

Viruses continue to threaten human health. Yet, the complete viral species carried by humans and their infection characteristics have not been fully revealed.

RESULTS

This study curated an atlas of human viruses from public databases and literature, and built the Human Virus Database (HVD). The HVD contains 1,131 virus species of 54 viral families which were more than twice the number of the human-infecting virus species reported in previous studies. These viruses were identified in human samples including 68 human tissues, the excreta and body fluid. The viral diversity in humans was age-dependent with a peak in the infant and a valley in the teenager. The tissue tropism of viruses was found to be associated with several factors including the viral group (DNA, RNA or reverse-transcribing viruses), enveloped or not, viral genome length and GC content, viral receptors and the virus-interacting proteins. Finally, the tissue tropism of DNA viruses was predicted using a random-forest algorithm with a middle performance. Overall, the study not only provides a valuable resource for further studies of human viruses, but also deepens our understanding towards the diversity and tissue tropism of human viruses.

AVAILABILITY

The HVD is available at http://computationalbiology.cn/humanVirusBase/#/.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

The cell‐free DNA virome of 108,349 Dutch pregnant women

OBJECTIVE

Viral infections during pregnancy are a major health concern to mother and fetus. By repurposing cell-free Non Invasive Prenatal Testing (NIPT) sequencing data, we investigated prevalence and abundance of viral DNA in a cohort of 108,349 pregnant women.

METHOD

Cell-free DNA (cfDNA) sequencing reads that did not map to any of the human chromosomes or mitochondrial DNA of the human reference genome build GRCh38 were aligned to 224 DNA viruses selected from the NCBI refseq viral database.

RESULTS

In total 443,665 reads of viral origin were detected across 42,273 samples representing 165 viral species. Several are known to be potentially harmful during pregnancy and/or childbirth, including Cytomegalovirus, Parvovirus B19 and Hepatitis B. Viral sequences were mostly detected at very low abundance. However, several cases had exceptionally high viral loads for Parvovirus B19, Hepatitis B and others. We found statistically significant associations between presence of viral DNA and gestational age, maternal age, fetal fraction, cfDNA concentration and others.

CONCLUSION

We demonstrate the feasibility to detect viral DNA from typical genome-wide NIPT cfDNA sequencing and describe the main characteristics of the viral DNA in our cohort. Our dataset of detected viral sequence reads is made publicly available to guide future clinical implementations.