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PubMed2026

Phylogeography and molecular evolution of Newcastle disease virus across a century of global surveillance.

Newcastle disease virus (NDV) remains one of the most economically important avian pathogens worldwide, causing recurrent outbreaks in poultry despite decades of vaccination and disease control efforts. Since the first reported outbreak of NDV a hundred years ago, numerous molecular epidemiological studies have been conducted globally across diverse geographic and production settings. Following a century of NDV circulation and evolution, the present study aimed to compile all publicly available NDV sequence data and perform a comprehensive global analysis of the genetic diversity, phylogenetic relationship, and global spatiotemporal distribution of NDV over a 100-year timescale. All publicly available NDV complete genome and full-length fusion (F) gene sequences were retrieved from GenBank up to February 2026. Following rigorous quality control, phylogenetic analyses were performed based on complete genomes and F gene datasets. Phylogenetic analysis identified two genotypes within Class I and 20 genotypes within Class II NDVs, with extensive diversification at the sub-genotype level. Genotype XIII exhibited the greatest sub-genotypic diversity, while genotype VII represented the most globally disseminated genotype, reported across 36 countries. Chronological assessment based on the earliest available reports indicated an increasing number of recognized genotypes from the 1930s to recently described sub-genotypes such as XIII.2.3 and XXII.2.2. Regional diversity analysis revealed the highest genotype diversity in Western Africa, Eastern Asia, and Southern Asia. Comparative residue analysis demonstrated substantial genotype-specific variation within critical functional domains of the fusion protein, including cleavage sites, neutralizing epitopes, and heptad repeat regions. Overall, this study provides the first comprehensive 100-year global overview of NDV evolution and phylogeography. The findings highlight continuous viral diversification, broad geographic dissemination of multiple genotypes, and ongoing molecular variation, emphasizing the need for sustained genomic surveillance and periodic evaluation of vaccine compatibility with emerging NDV genotypes.

100-years of data↗

PubMed2011

Recombination in eukaryotic single stranded DNA viruses.

Although single stranded (ss) DNA viruses that infect humans and their domesticated animals do not generally cause major diseases, the arthropod borne ssDNA viruses of plants do, and as a result seriously constrain food production in most temperate regions of the world. Besides the well known plant and animal-infecting ssDNA viruses, it has recently become apparent through metagenomic surveys of ssDNA molecules that there also exist large numbers of other diverse ssDNA viruses within almost all terrestrial and aquatic environments. The host ranges of these viruses probably span the tree of life and they are likely to be important components of global ecosystems. Various lines of evidence suggest that a pivotal evolutionary process during the generation of this global ssDNA virus diversity has probably been genetic recombination. High rates of homologous recombination, non-homologous recombination and genome component reassortment are known to occur within and between various different ssDNA virus species and we look here at the various roles that these different types of recombination may play, both in the day-to-day biology, and in the longer term evolution, of these viruses. We specifically focus on the ecological, biochemical and selective factors underlying patterns of genetic exchange detectable amongst the ssDNA viruses and discuss how these should all be considered when assessing the adaptive value of recombination during ssDNA virus evolution.

Animals↗

PubMed2026

Nipah virus in the era of global connectivity: molecular evolution, transmission risk, and preparedness strategies.

Nipah virus (NiV) is a highly pathogenic zoonotic RNA virus belonging to the genus Henipavirus within the family Paramyxoviridae, representing a continuing global health concern due to its high case fatality rate and potential for epidemic expansion in the era of increasing international connectivity. The virus demonstrates strong evolutionary adaptability driven by the absence of proofreading mechanisms during RNA replication, enabling genetic diversification that may influence host range, virulence, and transmission dynamics. Molecular pathogenesis of NiV is primarily mediated through interaction of viral glycoproteins with ephrin-B2 and ephrin-B3 receptors, facilitating host cell entry, endothelial damage, and neuroinvasion. Immune evasion facilitated by the action of accessory proteins encoded by the P gene (P, V, W, and C) acts to suppress innate antiviral immunity through the inhibition of interferon induction and JAK/STAT signaling. Human-to-human transmission of Nipah virus remains limited, with epidemiological evidence indicating basic reproduction numbers generally below unity; however, respiratory involvement and healthcare-associated exposure may enhance cluster outbreaks. Global travel, ecological disruption, and fragmented surveillance systems contribute to spillover risk, particularly in South and Southeast Asia where fruit bats of the genus Pteropus serve as natural reservoirs. Despite advances in vaccine technology, including subunit, viral vector, mRNA-based platforms, and monoclonal antibody therapies, no licensed prophylactic or therapeutic agent is currently available for human use. Global preparedness remains challenged by the scarcity of high-containment biosafety facilities, limited research funding, and absence of integrated One Health surveillance networks. Ethical considerations surrounding wildlife population control further complicate disease mitigation strategies. Emerging genomic surveillance, artificial intelligence-assisted predictive modeling, and regional data-sharing frameworks are essential for early detection and response. Strengthening molecular research on viral-host interactions and transmission determinants will be critical for preventing future Nipah virus outbreaks in an increasingly interconnected world.

Genomic surveillance↗

PubMedDate not supplied

[Relations between human and animal influenza viruses].

The following more important problems are dealth with in the present paper:--antigenic relationships between human and animal influenza viruses;--recombination of human and animal influenza viruses;--epidemiological relationships between human and animal influenza viruses;--the theory of cyclical evolution of influenza viruses.

Animals↗

PubMed2026

Application of emerging technologies in the antiviral field.

Viral diseases pose a serious threat to global public health, agriculture, and biosecurity. Conventional antiviral strategies are often limited by an incomplete understanding of disease mechanisms, poor targeting precision, and slow response times. Emerging technologies are now reshaping the landscape of antiviral research. This review examines the roles of four key frontiers, including organoid models, gene editing, AI-driven molecular design, and synthetic biology. Organoids provide physiologically relevant platforms that model virus-host interactions and disease progression. Viral infections remain a major challenge to human and animal health, agriculture, and biosecurity. Progress in antiviral research is constrained by the complexity of viral pathogenesis, the diversity and rapid evolution of viruses, and the limited translational relevance of some traditional model systems. Recent advances in organoid technology, gene editing, artificial intelligence, and synthetic biology are expanding the toolkit available for antiviral research and development. In this review, we discuss how these four technological frontiers contribute to disease modeling, target discovery, molecular design, and translational innovation. Organoids, in particular, provide physiologically relevant systems for investigating viral infection, tissue tropism, host responses, and pathogenesis. Gene editing tools, such as CRISPR, enable precise manipulation of host and viral genomes, facilitating the development of resistant organisms and next-generation vaccine platforms. AI technologies, including AlphaFold for structure prediction and platforms for de novo protein design, address long-standing bottlenecks in structural biology and offer powerful means to engineer antiviral proteins, antibodies, and vaccine antigens. Synthetic biology, guided by the Design-Build-Test-Learn cycle, integrates computational design, genetic assembly, and functional validation into a cohesive pipeline. Together, these technologies form a synergistic workflow that spans disease modeling, target discovery, molecular design, construction, testing, and iterative optimization. This integrated approach is shifting antiviral development from traditional empirical methods toward more precise, intelligent strategies. The review also highlights ongoing challenges in integration and scalability, stressing that high-quality biological datasets and stronger interdisciplinary collaboration are essential for realizing translational potential. By presenting a cohesive view of these converging methodologies, this review offers a framework to guide the intelligent evolution of antiviral strategies in both human and animal health.

Antiviral↗

PubMed2025

Analysis of Leishbuviridae from Trypanosomatids.

Over the last decade, considerable progress has been made in unraveling RNA virus diversity. This has contributed to our understanding of the evolution of these viruses, which include emerging zoonotic human pathogens. Current success has been greatly facilitated by the development of next-generation sequencing platforms instrumental for meta-transcriptomic studies. However, due to the rapid evolution of RNA viruses, there are numerous "blind spots" waiting to be explored; one of those is the RNA virome of unicellular eukaryotes. Here, we present the pipeline, which has been successfully used to characterize various types of RNA viruses, including Leishbuviridae (Bunyaviricetes, Hareavirales) in the parasitic flagellates of the family Trypanosomatidae. The pipeline relies on axenic in vitro cell culture and double-stranded RNA enrichment, followed by direct RNA-sequencing. A detailed procedure description starting from the initial total RNA preparation to the final assembly of the viral segments is provided.

High-Throughput Nucleotide Sequencing↗

PubMed2025

Evolution of primate T-cell leukemia virus type 1 accessory genes and functional divergence of its antisense proteins.

Human T-cell leukemia virus type 1 (HTLV-1) is derived from simian T-cell leukemia virus type 1 (STLV-1), and together they form a broader category known as primate T-cell leukemia virus type 1 (PTLV-1). PTLV-1 encodes multiple proteins from overlapping open reading frames (ORFs) in the pX region. This study aims to characterize the conservation of these proteins in different PTLV-1 subtypes and their role in pathogenesis. For the first time, we report the full-length proviral sequence of an STLV-1 strain isolated from chimpanzee and African green monkey. Phylogenetic analysis reveals high conservation of the accessory proteins p12, p30, and p13 in the HTLV-1a subtype. Conversely, some African PTLV-1 subtypes exhibit loss of ORFs for p12 or p13. For Asian subtypes, simian strains often lack p12, p13, or p30 proteins, whereas human strains retain the ORFs of p30 and p13 but not p12. To assess the infectivity of a simian strain of PTLV-1 lacking ORFs for p12, p13, and p30, we constructed a molecular clone from a naturally infected Japanese macaque (Mfu: Macaca fuscata) and compared it with HTLV-1a. Using a reporter assay and ELISA, we found similar infectivity to Jurkat T cells; however, STLV-1 Mfu exhibited impaired infectivity in the monocytic cell line THP-1. Additionally, despite the conservation of the HTLV-1/STLV-1 bZIP factor (HBZ/SBZ) ORFs, HBZ/SBZ proteins derived from HTLV-1a and African PTLV-1 subtypes induce significantly higher activation of the TGF-β/Smad signaling pathway than those from Asian subtypes. Collectively, our findings suggest that the acquisition of the accessory proteins by PTLV-1 subtypes potentially confers an advantageous adaptation of PTLV-1 during infection in apes, including humans. Moreover, among PTLV-1 strains, HBZ/SBZ had varying degrees of activity on the TGF-β/Smad pathway; this fact underscores the complex interplay between viral proteins and host signaling pathways, possibly influencing the viral pathogenicity in different species.

Animals↗

PubMed2026

Reducing haystacks to needles - ViralClust: A Nextflow pipeline to cluster viral sequences.

BACKGROUND: The rapid accumulation of viral genome sequences presents major challenges for downstream analysis tools, including tools for multiple sequence alignments, phylogeny, and genome/alignment visualization, due to computational constraints and sampling biases caused by outbreak-driven over-representation. Selecting representative genomes through clustering offers a principled alternative to random subsampling, yet choosing appropriate clustering strategies remains non-trivial and context-dependent. RESULTS: Here, we present ViralClust, a modular Nextflow pipeline for bias-aware representative selection from large viral genome datasets. ViralClust integrates five distinct clustering algorithms (CD-HIT-EST, SUMACLUST, VSEARCH, MMSeqs2, and HDBSCAN) within a unified workflow, enabling direct comparison of clustering outcomes and flexible adaptation to diverse biological questions, considering a balanced phylogenetic distribution of the selected sequences. We evaluated ViralClust on six RNA and DNA virus datasets ranging from 632 to 156,586 sequences and spanning genome lengths from 890 to 197,185 nucleotides. Across all datasets, clustering reduced dataset size by ~95 % or more while preserving genetic diversity across species, genera, and families, and effectively mitigating biases introduced by outbreaks, partial genomes, and sequence orientation artifacts. CONCLUSIONS: By supporting whole-genome clustering and scalable representative selection, ViralClust enables efficient and reproducible downstream analyses that would otherwise be computationally infeasible. Rather than offering a prescriptive, guided analysis engine, our framework functions as a flexible comparative collection of complementary strategies, allowing users to empirically evaluate trade-offs and choose the ideal method tailored to their specific analytical endpoints.

Bioinformatics↗

PubMed2024

Frequent nonhomologous replacement of replicative helicase loaders by viruses in Vibrionaceae.

Several microbial genomes lack textbook-defined essential genes. If an essential gene is absent from a genome, then an evolutionarily independent gene of unknown function complements its function. Here, we identified frequent nonhomologous replacement of an essential component of DNA replication initiation, a replicative helicase loader gene, in Vibrionaceae. Our analysis of Vibrionaceae genomes revealed two genes with unknown function, named vdhL1 and vdhL2, that were substantially enriched in genomes without the known helicase-loader genes. These genes showed no sequence similarities to genes with known function but encoded proteins structurally similar with a viral helicase loader. Analyses of genomic syntenies and coevolution with helicase genes suggested that vdhL1/2 encodes a helicase loader. The in vitro assay showed that Vibrio harveyi VdhL1 and Vibrio ezurae VdhL2 promote the helicase activity of DnaB. Furthermore, molecular phylogenetics suggested that vdhL1/2 were derived from phages and replaced an intrinsic helicase loader gene of Vibrionaceae over 20 times. This high replacement frequency implies the host's advantage in acquiring a viral helicase loader gene.

Vibrionaceae↗

PubMed2026

Tracing the evolution and diversity of human parvovirus B19 across human history.

Human parvovirus B19 (B19V) is an ubiquitously spread, exclusively human pathogen, mainly posing risks to children, as well as pregnant and immunocompromised individuals. Despite evidence of B19V infection of human populations as far back as 7,000 years, the evolutionary history of B19V remains poorly understood. In this study, we present B19V genomic data from the remains of 53 globally distributed individuals spanning more than 8,000 years, including 7 children. Our findings suggest that the most recent common ancestor of all present B19V lineages existed around 12,000 years ago, at the end of the last Ice Age. Additionally, we identified an extinct Eurasian clade that participated in the recombination event that led to the emergence of B19V genotype 2 (GT-2). We date this event to ∼3,200-1,800 BP, potentially in the greater Mediterranean area. Our study shows aspects of how ancient parvovirus variants arose, disseminated, and impacted human health through time.

ancient DNA↗

PubMed2025

Genome-scale evolution and phylodynamics of swine influenza A viruses in China: a genomic epidemiology study.

BACKGROUND: Pigs are recognised as crucial intermediate hosts for the emergence of influenza viruses of pandemic potential. As the largest pork-producing nation, China hosts a complex ecosystem of swine influenza viruses (SIVs). We aimed to investigate the evolutionary processes, spatiotemporal dynamics, and biological characteristics of SIVs in China. METHODS: From Jan 15, 2016, to Dec 22, 2020, we collected nasal swabs from pigs at eight abattoirs and 16 swine farms in the Guangdong, Henan, and Shandong provinces of China, as part of SIV surveillance. SIVs were detected with RT-PCR. Positive samples underwent viral isolation and genome sequencing. We analysed evolution and spatiotemporal dynamics using the whole genomes of isolated SIVs, as well as genome sequences of SIV isolates from human infections worldwide retrieved from the Global Initiative on Sharing All Influenza Data and GenBank Flu databases up to April 28, 2024. Viral sequences without a sample collection area or date were excluded from the analysis. Viral receptor-binding properties and in-vitro replication of strains isolated in this study were evaluated with a solid-phase binding assay and various cell lines, including Madin-Darby canine kidney cells, porcine alveolar macrophages, primary porcine trachea epithelial cells, human bronchial epithelioid, and human lung adenocarcinoma epithelial (A549) cells. Viral replication and transmission studies were conducted in 33 guinea pigs and 13 pigs. Additionally, we collected serum samples from pig farm workers and members of the general public recruited by the Third Affiliated Hospital of Sun Yat-sen University between Feb 28 and May 11, 2023, to detect specific antibodies against Eurasian avian-like A(H1) and human-like A(H3N2) SIVs using the haemagglutination inhibition assay. FINDINGS: 23 (1·3%) of 1818 nasal swabs collected in abattoirs had SIVs; 22 (0·9%) of 2375 swabs from swine farms had SIVs. Further viral isolation yielded 39 strains of SIV. We identified 534 A(H1N1), 69 A(H1N2), and 92 A(H3N2) SIVs, representing 20 genotypes within the Eurasian avian-like lineage, 14 within the classical swine A(H1) lineage, and 16 within the human-like A(H3N2) lineage. The introduction of the A(H1N1)pdm/09 virus significantly influenced the internal gene pool of SIVs, enhancing genotypic diversity in China. Notably, the Eurasian avian-like A(H1), classical swine A(H1), and human-like A(H3N2) lineages showed human-mediated spread over long distances between provinces, with the Eurasian avian-like A(H1) lineage showing the most prevalent spread pathways. Eurasian avian-like A(H1) SIVs showed a preference for binding to sialic acid α-2,6 glycan receptors, predominantly found in humans, resulting in an increased production of progeny viruses in human airway epithelial cells, as well as effective transmission and infectivity among guinea pigs and pigs. Among 54 eligible serum samples collected from pig farm workers (24 from slaughterhouses and 30 from swine farms), 23 (43%) were seropositive for Eurasian avian-like A(H1) SIVs and 46 (85%) for human-like A(H3N2) SIVs. Among 100 eligible samples from members of the general public, 14 (14%) were seropositive for Eurasian avian-like A(H1) SIVs and 85 (85%) for human-like A(H3N2) SIVs. INTERPRETATION: This study elucidates the evolutionary processes and spatiotemporal patterns of SIVs, highlighting potential risks to public health. These findings are crucial for informing public health interventions that aim to prevent future SIV epidemics in China and other countries worldwide. FUNDING: Scientific Innovation Strategy-Construction of High-Level Academy of Agriculture Science-Distinguished Scholar (R2020PY-JC001).

Animals↗

PubMed2009

Directed evolution of adeno-associated virus for glioma cell transduction.

Glioblastoma multiforme (GBM) is a serious form of brain cancer for which there is currently no effective treatment. Alternative strategies such as adeno-associated virus (AAV) vector mediated-genetic modification of brain tumor cells with genes encoding anti-tumor proteins have shown promising results in preclinical models of GBM, although the transduction efficiency of these tumors is often low. As higher transduction efficiency of tumor cells should lead to enhanced therapeutic efficacy, a means to rapidly engineer AAV vectors with improved transduction efficiency for individual tumors is an attractive strategy. Here we tested the possibility of identifying high-efficiency AAV vectors for human U87 glioma cells by selection in culture of a newly constructed chimeric AAV capsid library generated by DNA shuffling of six different AAV cap genes (AAV1, AAV2, AAV5, AAVrh.8, AAV9, AAVrh.10). After seven rounds of selection, we obtained a chimeric AAV capsid that transduces U87 cells at high efficiency (97% at a dose of 10(4) genome copies/cell), and at low doses it was 1.45-1.6-fold better than AAV2, which proved to be the most efficient parental capsid. Interestingly, the new AAV capsid displayed robust gene delivery properties to all glioma cells tested (including primary glioma cells) with relative fluorescence indices ranging from 1- to 14-fold higher than AAV2. The selected vector should be useful for in vitro glioma research when efficient transduction of several cell lines is required, and provides proof-of-concept that an AAV library can be used to generate AAV vectors with enhanced transduction efficiency of glioma cells.

Capsid Proteins↗

PubMed2025

The potential impacts of human genetics on virus emergence.

Human monogenic traits can confer resistance to viral infection in exposed individuals or predisposition to severe disease in infected individuals. Enhanced susceptibility can be driven directly by mutations in genes essential for control of the virus or indirectly via the production of autoantibodies against components of host defense. While the impact of viruses on individuals carrying these genotypes permitted their identification and has been amply studied, little is known about the impact of these human genotypes on the natural history of viruses, including not only persisting but also emerging viruses. We envisage several scenarios, including the possibility that genetically susceptible individuals serve as patient zeros, superspreaders, or mutation incubators, or that genetically resistant individuals even permit the selection of new viral mutants. Viruses are continually shared between individuals and even host species, where they can benefit from adaption to new environments. Current human viruses, as well as novel viruses from animal reservoirs, will continue to threaten the human population. Improvements in the scale of human genomic sequencing and analysis will permit testing hypotheses about the impact of human genetics on the origin and trajectory of viral infections, including future pandemics, which may ultimately help to prevent or curtail impending outbreaks.

Humans↗

PubMed2025

Molecular Evolution and Zoonotic Potential of Muju Virus (Orthohantavirus puumalaense) in Craseomys regulus, Republic of Korea.

Orthohantavirus puumalaense causes hemorrhagic fever with renal syndrome in Europe, with Puumala virus (PUUV) as its primary representative. Muju virus (MUJV), harbored by Craseomys regulus, an Arvicolinae rodent species endemic to the Republic of Korea (ROK), is also a genotype of O. puumalaense. However, their genomic diversity and zoonotic potential remain largely unknown. To investigate their prevalence, 185 voles were collected from 23 regions of the ROK between 2012 and 2023. Serological assays detected anti-PUUV immunoglobulin G antibodies in five samples (3.1%), whereas reverse-transcription polymerase chain reaction confirmed MUJV RNA in identical specimens (2.7%). Amplicon-based nanopore sequencing facilitates near-complete genome recovery, enabling high-resolution comparative analysis. Phylogenetic analysis revealed distinct genetic lineages in Gangwon and Jeollabuk Provinces. Evolutionary rate estimates indicated greater sequence divergence in the S and L segments than in the M segment. A zoonotic risk assessment revealed that most MUJV variants exhibited moderate-to-high spillover potential. The molecular detection of MUJV in Cheorwon, Gangwon Province, expands its known geographic range and provides the first molecular evidence of MUJV circulation in this region. These findings highlight the need for continued surveillance and seroprevalence studies of MUJV to assess its potential for human exposure and public health relevance in the ROK.

Animals↗

PubMed2026

[Genomic evolution and epidemiological patterns of respiratory syncytial virus and their implications for surveillance and early warning].

Respiratory syncytial virus (RSV) is an important respiratory pathogen in infants, young children and older adults. Based on global RSV genomic surveillance data, this review systematically summarizes the geographic distribution, seasonal epidemic patterns, and long-term evolutionary trends of RSV, with particular emphasis on the sustained circulation and evolutionary mechanisms of dominant genotypes such as ON1 in RSV-A and BA9 in RSV-B. Current evidence indicates that RSV transmission dynamics are tightly coupled with viral evolution. The G gene evolves relatively rapidly and contains multiple positively selected sites, suggesting an important role in immune escape and population adaptation. In recent years, changes in social behavior patterns and population immunity have further disrupted the seasonal rhythm of RSV and may have influenced the spread of dominant genotypes. Under routine respiratory infectious disease surveillance, strengthened genomic monitoring and integration of multi-source data are needed to improve early warning of abnormal RSV epidemics and variant-associated risks, thereby providing prospective evidence for protecting high-risk populations and informing public health decision-making.

Humans↗

PubMed2017

A directed evolution approach to select for novel Adeno-associated virus capsids on an HIV-1 producer T cell line.

A directed evolution approach was used to select for Adeno-associated virus (AAV) capsids that would exhibit more tropism toward an HIV-1 producer T cell line with the long-term goal of developing improved gene transfer vectors. A library of AAV variants was used to infect H9 T cells previously infected or uninfected by HIV-1 followed by AAV amplification with wild-type adenovirus. Six rounds of biological selection were performed, including negative selection and diversification after round three. The H9 T cells were successfully infected with all three wild-type viruses (AAV, adenovirus, and HIV-1). Four AAV cap mutants best representing the small number of variants emerging after six rounds of selection were chosen for further study. These mutant capsids were used to package an AAV vector and subsequently used to infect H9 cells that were previously infected or uninfected by HIV-1. A quantitative polymerase chain reaction assay was performed to measure cell-associated AAV genomes. Two of the four cap mutants showed a significant increase in the amount of cell-associated genomes as compared to wild-type AAV2. This study shows that directed evolution can be performed successfully to select for mutants with improved tropism for a T cell line in the presence of HIV-1.

Capsid↗

PubMed2025

Variable rates of SARS-CoV-2 evolution in chronic infections.

An important feature of the evolution of the SARS-CoV-2 virus has been the emergence of highly mutated novel variants, which are characterised by the gain of multiple mutations relative to viruses circulating in the general global population. Cases of chronic viral infection have been suggested as an explanation for this phenomenon, whereby an extended period of infection, with an increased rate of evolution, creates viruses with substantial genetic novelty. However, measuring a rate of evolution during chronic infection is made more difficult by the potential existence of compartmentalisation in the viral population, whereby the viruses in a host form distinct subpopulations. We here describe and apply a novel statistical method to study within-host virus evolution, identifying the minimum number of subpopulations required to explain sequence data observed from cases of chronic infection, and inferring rates for within-host viral evolution. Across nine cases of chronic SARS-CoV-2 infection in hospitalised patients we find that non-trivial population structure is relatively common, with five cases showing evidence of more than one viral population evolving independently within the host. The detection of non-trivial population structure was more common in severely immunocompromised individuals (p = 0.04, Fisher's Exact Test). We find cases of within-host evolution proceeding significantly faster, and significantly slower, than that of the global SARS-CoV-2 population, and of cases in which viral subpopulations in the same host have statistically distinguishable rates of evolution. Non-trivial population structure was associated with high rates of within-host evolution that were systematically underestimated by a more standard inference method.

Humans↗

PubMed2024

Gene transfer agents: The ambiguous role of selfless viruses in genetic exchange and bacterial evolution.

Gene transfer agents (GTAs) are genetic elements derived from ancestral bacteriophages that have become domesticated by the host. GTAs are present in diverse prokaryotic organisms, where they can facilitate horizontal gene transfer under certain conditions. Unlike typical bacteriophages, GTAs do not exhibit any preference for the replication or transfer of the genes encoding them; instead, they exhibit a remarkable capacity to package chromosomal, and sometimes extrachromosomal, DNA into virus-like capsids and disseminate it to neighboring cells. Because GTAs resemble defective prophages, identification of novel GTAs is not trivial. The detection of candidates relies on the genetic similarity to known GTAs, which has been fruitful in α-proteobacterial lineages but challenging in more distant bacteria. Here we consider several fundamental questions: What is the true prevalence of GTAs in prokaryote genomes? Given there are high costs for GTA production, what advantage do GTAs provide to the bacterial host to justify their maintenance? How is the bacterial chromosome recognized and processed for inclusion in GTA particles? This article highlights the challenges in comprehensively understanding GTAs' prevalence, function and DNA packaging method. Going forward, broad study of atypical GTAs and use of ecologically relevant conditions are required to uncover their true impact on bacterial chromosome evolution.

Gene Transfer, Horizontal↗