Biology subjects

Bellas, C.

Publications and source records attributed to Bellas, C..

5 recordsLinked to original sources

bioRxiv2026

Single-cell-resolved natural giant virus infections reveal conserved protist immunity

Single-cell eukaryotes (protists) are key players in microbial ecosystems. Yet, our understanding of how they interact with viruses in nature and how antiviral defenses shape these relationships remains limited. Using a single-cell multi-omics approach, we mapped associations between giant viruses and their hosts and identified active giant-virus infections in an alpine lake protist community. In naturally infected dinoflagellates, infection was accompanied by the selective induction of viperin, an ancient antiviral enzyme conserved from bacteria to humans. We also observed virus-encoded homologs of immunity-related genes whose expression correlated with viperin expression, raising the possibility of a role in viral counter-defense. These findings reveal an ecological dimension of protist immunity and provide a framework for tracing the host-virus arms race across divergent cellular lineages.

microbiology↗

bioRxiv2026

Integrating bacterial and viral genomic information enhances and extends the machine learning predictions of bacteriophage activity against pathogenic Escherichia coli

The use of bacteriophage (phage) to treat bacterial infections is undergoing a resurgence due to the rise of antibiotic resistance. Pathogenic Escherichia coli, including extraintestinal pathotypes such as uropathogenic E. coli (UPEC), pose a substantial clinical burden with the challenge of multi-drug resistance strains, making it important to progress alternative treatment options such as those based on phage. One major hurdle is selecting effective phage combinations against an infecting strain while accounting for the multiple mechanisms that determine phage susceptibility and bacterial resistance. We previously analysed over 9000 interactions between 31 phage and 314 sequenced E. coli and built machine learning models to predict phage activity against "unseen" E. coli based on these scores and bacterial genome sequence data. However, this approach did not leverage phage gene content, limiting its ability to generalise across phage. Here, we advance this framework by combining bacterial and phage pangenomes into a single predictive model, allowing gene content across related phage as well as bacteria to be incorporated as machine learning features. This unified approach increased predictive accuracy relative to the single-phage models and produced a single model capable of predicting previously unseen phage-E. coli interactions. In leave-phage-out analyses, it also predicted activity for phages whose interaction data were entirely excluded from training. The genomic features most consistently contributing to prediction included bacterial determinants of surface recognition and anti-phage defence, alongside phage-associated features, indicating that this combined model, termed "PanPhage", captures genetic information relevant to multiple stages of the phage-host interaction.

microbiology↗

bioRxiv2026

A framework for Polinton-like virus diversity across aquatic microbiomes reveals links to multiple viral classes and Nucleocytoviricota

Polinton-like viruses (PLVs) are among the most abundant eukaryotic DNA viruses in aquatic environments. Despite their extensive diversity, broad host range and variable gene content, they are commonly treated as a single group, which obscures their evolutionary relationships and complicates their classification. Through analysing thousands of viral genomes from aquatic ecosystems and public metagenomic datasets, we clarify the evolutionary structure encompassed by the term PLV. Using sensitive profile Hidden Markov Model (HMM) comparisons, phylogenies of conserved capsid morphogenetic genes and gene content analysis, we show that viruses referred to as PLVs are distributed across multiple deep lineages spanning at least three currently recognised viral classes. These include the Gosseviruses, aquatic viruses related to Maverick-Polintons in animal genomes. They also include a continuum of related viruses from 15 kb PLVs to the 45 kb Mriyaviruses and more broadly, to the Nucleocytoviricota, potentially representing extant relatives of giant viruses. Our findings suggest that PLVs do not fit neatly within existing taxonomic boundaries, reflecting a complex history of horizontal gene transfer and diversification of life strategies. To support future discovery, we provide a curated set of HMMs representing the known capsid diversity of PLVs, Maverick-Polintons, and virophages. This toolkit enables sensitive detection and identification of PLVs across metagenomic and eukaryotic genome datasets. Our study provides an evolutionary framework for interpreting PLV diversity and a foundation for future refinement of their classification.

microbiology↗

bioRxiv2026

Expansive Diversity and Temporal Dynamics of Emerging Polinton-like Viruses in a Marine Ecosystem

Polinton-like viruses (PLVs) are an emerging group of double-stranded DNA viruses of microbial eukaryotes whose ecological roles in marine ecosystems remain poorly understood. Using a five-year monthly viromic time series from the San Pedro Ocean Time-series (SPOT), we investigated the diversity, temporal dynamics, and functional potential of PLVs in a coastal marine ecosystem. We identified 2,355 distinct PLV populations, revealing PLVs to be a highly abundant and diverse component of the marine virosphere. Phylogenetic analyses resolved multiple major PLV clades, including abundant Group X/Trimcap PLVs characterized by triplicate major capsid proteins, supporting the widespread occurrence of this unusual viral architecture in marine PLVs. Approximately half of PLV populations exhibited significant repeatable seasonal dynamics, partitioning into numerous chronotypes that reflect highly modular temporal niches. PLV abundance correlated positively with multiple productivity-linked environmental variables, including nitrate, particulate organic carbon, and primary productivity, suggesting close coupling between PLVs and seasonal ecosystem productivity. Functional analyses further identified diverse auxiliary metabolic genes in many PLV genomes involved in carbohydrate, lipid, redox, and nucleotide metabolism, with strong phylogenetic structuring across PLV clades. Together, these findings demonstrate that PLVs are abundant, functionally diverse, and ecologically dynamic members of marine viral communities, and suggest they are important yet underappreciated regulators of protist ecology and evolution in marine ecosystems.

microbiology↗

bioRxiv2019

A simple method for spray-on gene editing in planta.

Potential innovation in Plant research using gene-edited and genetically modified plants is currently being hindered by inefficient and costly plant transformation. We show that carbon dots formed from natural materials (quasi-spherical, <10nm nanoparticles) can act as a fast vehicle for carrying plasmids into mature plant cells, resulting in transient plant transformation in a number of important crop species with no negative impacts on photosynthesis or growth. We further show that GFP, Cas9, and gRNA introduced into wheat via foliar application (spraying on) of plasmid coated carbon dots are expressed and, in the case of Cas9, make genome edits in SPO11 genes. Therefore, we present a protocol for spray-on gene editing that is simple, inexpensive, fast, transforms in planta, and is applicable to multiple crop species. We believe this technique creates many opportunities for the future of plant transformation in research and shows great promise for plant protein production systems.

plant biology↗