PhageTRAP: An ERC-Funded Platform Aims to Simplify Phage Capture and Purification
A new European Research Council project at the University of Vienna is developing a technology that could simplify two persistent bottlenecks in bacteriophage development: finding useful phages and separating them efficiently from the complex bacterial material in which they are produced.
PhageTRAP, formally titled “A Device for Phage Capture and Release,” is led by microbial biochemist Professor Thomas Böttcher at the University of Vienna. The project has received €150,000 through the ERC Proof of Concept programme and runs from April 1, 2026 to September 30, 2027, following signature of the European Commission grant agreement on February 23, 2026.
Rather than developing a new therapeutic phage against one particular pathogen, PhageTRAP is focused on the technology used to handle phages themselves. The project aims to establish proof of concept for a modular platform in which synthetic molecular recognition motifs are immobilized on a solid support and used to selectively capture bacteriophages. Once retained, the viruses would subsequently be released, potentially creating a controllable capture-and-release system that could be adapted to phage screening, purification and cocktail construction.
The concept addresses a practical problem that begins almost immediately after a potentially useful phage is discovered. Environmental samples such as wastewater, soil or other microbial ecosystems can contain enormous numbers of bacteriophages, but identifying those capable of infecting a particular bacterial pathogen remains a relatively labor-intensive process. Candidate phages then need to be isolated, amplified, characterized and combined in ways that provide useful coverage against clinically relevant bacterial strains.
PhageTRAP proposes to introduce a molecular selection step into this process. According to the European Commission, the platform will use synthetic motifs attached to a solid material to capture selected phages and subsequently release them. The proof-of-concept programme will investigate different motifs associated with phages targeting Gram-positive bacterial pathogens and additional motifs intended to demonstrate that the approach can be customized for phages targeting Gram-negative bacteria.
Public descriptions of the project do not yet disclose the detailed chemical structures of these motifs or the precise molecular interactions responsible for phage capture. It would therefore be premature to describe them as mimics of particular bacterial receptors or to assign a specific binding mechanism. The central technological principle currently disclosed is selective and reversible phage binding through synthetic recognition chemistry.
This reversibility is essential. Simply attaching a phage strongly to a surface would have limited value if the viral particle could not subsequently be recovered while retaining infectivity. A useful platform must therefore balance efficient capture with controlled release while avoiding damage to the phage capsid, tail structures or receptor-binding machinery responsible for subsequent bacterial infection.
The project will test the technology using phages relevant to therapeutic applications as well as viruses recovered from environmental samples. This should allow the researchers to evaluate whether the same general platform can operate across biologically diverse phage populations rather than functioning only with a single laboratory virus.
Such diversity is a major challenge for any universal phage-processing technology. Bacteriophages vary substantially in size, morphology, capsid composition, surface properties, genome size and stability. Some tolerate substantial manipulation, while others lose infectivity after changes in pH, ionic strength, temperature or mechanical processing. A capture system intended for broad use therefore needs either considerable versatility or a genuinely modular architecture that can be adapted to different viral groups.
The second major application of PhageTRAP is purification. Therapeutic bacteriophages are usually amplified by allowing them to infect large populations of their bacterial host. Successful infection eventually produces a lysate containing not only newly generated phage particles but also the remains of the bacteria in which they replicated.
This material can include host-cell proteins, bacterial DNA and RNA, membrane fragments, culture-medium components and other biological contaminants. When Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa or Klebsiella pneumoniae are used for propagation, lipopolysaccharide-derived endotoxin becomes a particularly important concern because excessive contamination can trigger inflammatory reactions.
Removing these materials while maintaining a high concentration of infectious phages is one of the central downstream-processing challenges in therapeutic manufacturing. Purification therefore has to achieve two goals that can sometimes conflict: eliminating bacterial material sufficiently for a safe preparation while preserving as much active phage as possible.
Numerous approaches are already used. Laboratory workflows can incorporate centrifugation, filtration, polyethylene glycol precipitation, density-gradient ultracentrifugation, ultrafiltration, tangential-flow filtration and different forms of chromatography. More advanced manufacturing strategies increasingly use anion-exchange chromatography, membrane chromatography and other scalable techniques designed to combine contaminant removal with acceptable phage recovery.
No single method is ideal for every bacteriophage. Viral particles can differ sufficiently in their physical and chemical properties that a purification protocol optimized for one phage may produce poor yields or incomplete contaminant removal for another. Additional steps can improve purity but may also increase processing time, cost and losses of infectious particles.
This variability becomes particularly problematic when therapeutic development involves large phage libraries or personalized treatment. A centre may need to process many different phages rather than repeatedly manufacture one fixed biological product. Developing an entirely separate purification protocol for each candidate can make rapid clinical translation difficult.
PhageTRAP is designed around a different principle: capture the phage selectively rather than relying primarily on broader differences in size, density or charge between the virus and contaminants. If selective capture works reliably, unwanted bacterial components could theoretically be washed away while the phage remains immobilized, after which the virus could be released into a cleaner preparation.
Affinity-based purification is not entirely new to phage research. Earlier studies have demonstrated that bacteriophages engineered with affinity tags can bind specific chromatographic materials and subsequently be recovered. For example, T4 phages displaying affinity motifs have previously been purified using corresponding resins.
The distinction proposed by PhageTRAP is its modular synthetic recognition strategy and the ambition to apply it without turning every therapeutic phage into a genetically modified affinity-tagged virus. This could be important because modifying the genome or capsid of every candidate merely to simplify purification would create additional biological, manufacturing and regulatory complexity.
The project also connects purification with phage discovery. A capture material capable of enriching certain phages from environmental samples could potentially help researchers identify relevant viruses before extensive downstream screening. The same general technology might therefore operate at several stages of the development pipeline rather than serving only as the final purification step.
This is particularly relevant to therapeutic cocktail construction. Phage cocktails typically combine several viruses to broaden bacterial coverage, reduce dependence on a single host receptor or limit the probability that resistance to one phage immediately causes treatment failure.
Selecting complementary components can require testing large numbers of phage–bacterium interactions. The European Commission describes current identification and cocktail assembly as relatively slow and insufficiently systematic, and identifies high-throughput screening as one of the applications PhageTRAP intends to enable.
A modular capture system could potentially enrich, separate or process subsets of phages according to defined molecular interactions, making it easier to build structured phage collections and evaluate candidates systematically. The precise workflow remains to be demonstrated during the Proof of Concept project, but the objective is broader than conventional purification alone.
This makes PhageTRAP particularly complementary to emerging manufacturing infrastructures such as INFECTORY in the Netherlands. INFECTORY is developing shared GMP capacity for manufacturing small batches of pharmaceutical-quality bacteriophages for clinical research, whereas PhageTRAP targets one of the technological operations that can occur within or upstream of such manufacturing pipelines: capturing and purifying the viral particles themselves.
Phage manufacturing is increasingly becoming a central issue as the field moves from laboratory research and individual compassionate-use treatments toward controlled clinical development. Producing one clean research stock is very different from implementing a scalable and reproducible pharmaceutical process.
Clinical manufacturing requires knowledge of the production host, controlled amplification conditions, defined purification steps, analytical characterization, microbiological testing and traceability. The final preparation must retain adequate infectious potency while remaining within acceptable limits for contaminants.
Cocktails add another layer of complexity because each virus may require separate amplification and purification before the components are mixed. Different phages can respond differently to the same purification method, meaning that a process capable of treating multiple candidates through a common platform could substantially simplify early manufacturing.
Personalized phage therapy makes the problem even more pronounced. If treatment requires rapid selection of a virus matched to a patient's bacterial isolate, developers may not have the luxury of spending months optimizing a unique purification process for every phage selected from a library.
A modular capture technology could therefore become useful if recognition materials can be rapidly adapted to different phage categories while downstream operations remain largely standardized. That remains an intended advantage rather than an established capability, and demonstrating the breadth of the platform will be one of the important technical tests for PhageTRAP.
Recovery is another critical parameter. A purification system that produces exceptional purity but destroys most of the active phage would be difficult to use therapeutically. Every additional downstream step can reduce infectious titre through adsorption to surfaces, aggregation, shear, chemical exposure or incomplete recovery.
PhageTRAP will therefore need to demonstrate not simply that viruses can be bound to its synthetic motifs, but that capture is efficient, nonspecific binding remains manageable and released phages retain biological activity.
Scalability will also determine whether the platform can progress beyond an academic proof of concept. Techniques that work with small experimental volumes do not necessarily translate into manufacturing workflows handling much larger cultures. Solid-support systems must provide sufficient binding capacity, predictable flow characteristics and reproducible release while remaining economically realistic.
Another important question will be how efficiently contaminants are separated. Selective phage capture could simplify purification, but therapeutic preparations still require analytical confirmation that unwanted bacterial material has actually been reduced to appropriate levels. Endotoxin, host-cell DNA, proteins and other process-related impurities require independent measurement rather than assuming that phage capture automatically eliminates them.
For this reason, PhageTRAP should not be interpreted as replacing the entire downstream manufacturing process. Even if the capture technology performs exceptionally well, pharmaceutical production would still require filtration, formulation, sterility controls, potency testing, genomic characterization and other quality-control procedures depending on the intended product and route of administration.
Its potential advantage is instead to make one particularly difficult part of that process more selective, faster and potentially easier to standardize.
The Proof of Concept format is significant. ERC Proof of Concept grants are specifically intended to explore the application potential of results arising from ERC-funded research. They are smaller and shorter than major ERC frontier-research grants and focus more directly on demonstrating technical feasibility, translational potential and routes toward practical use.
Thomas Böttcher, who leads PhageTRAP, is Professor of Microbial Biochemistry at the University of Vienna with appointments at the Faculty of Chemistry and the Centre for Microbiology and Environmental Systems Science. His laboratory works at the intersection of chemistry and microbiology, studying molecular interactions between microorganisms, hosts and bacteriophages and developing chemical tools capable of manipulating microbial systems.
This chemical perspective is particularly relevant to PhageTRAP. Many phage-development programmes attempt to improve the virus itself through genome engineering, receptor-binding modification or directed evolution. PhageTRAP instead seeks to engineer the molecular environment used to select and process phages.
Böttcher has also led the ERC-funded CAPSID programme, which ran from 2020 to 2026 and investigated chemical regulation of lysogenic bacteriophages. CAPSID focused on small molecules capable of inducing or dysregulating prophages and on the chemical interactions governing phage–microbiome systems. While the public PhageTRAP descriptions do not explicitly establish every technical link between the two programmes, both reflect the laboratory's broader strategy of applying synthetic chemistry to phage biology.
The new project could also have applications outside medicine. Bacteriophages are increasingly investigated for food safety, agriculture, bacterial detection, industrial fermentation and targeted modification of microbial communities. These applications similarly require efficient isolation, concentration or purification of selected phages.
Industrial biotechnology may even tolerate different purity requirements from human therapy, potentially providing additional settings in which a capture platform could be developed and validated before more demanding pharmaceutical applications.
Nevertheless, the clinical ambition remains one of the strongest motivations. Phage therapy has repeatedly demonstrated that finding a biologically active virus is only the beginning of therapeutic development. Manufacturing, purification, formulation and quality control can become equally important constraints once a phage moves toward human administration.
A crude lysate that works perfectly in a laboratory plaque assay cannot simply be considered a therapeutic preparation. The biological system used to produce the phage inevitably contributes material to the product, and the downstream process must separate the desired viral particles from that background without compromising activity.
Recent developments in scalable chromatography and filtration have made substantial progress toward this objective. Anion-exchange approaches, cross-flow filtration and membrane-based purification systems can achieve considerable reductions in host-derived contaminants, while combinations of methods can bring endotoxin levels down dramatically.
Yet the diversity of phages remains a persistent manufacturing problem. Unlike conventional monoclonal antibodies, where production platforms can often be standardized across closely related molecules, phage products may consist of viruses belonging to very different structural and biological groups.
PhageTRAP's modularity is therefore arguably its most important proposed feature. Rather than claiming that one universal chemical surface can capture every bacteriophage, the project proposes interchangeable synthetic motifs that could be adapted according to the viruses researchers want to isolate.
The European Commission specifically describes different motifs for targets associated with Gram-positive bacteria and additional motifs intended to demonstrate customizable capture for Gram-negative pathogens. If successful, this would provide early evidence that the system can be redesigned rather than rebuilt when moving between clinically relevant phage groups.
However, the project remains at the proof-of-concept stage. There is currently no evidence that PhageTRAP has produced a validated GMP purification process, a commercial device or a therapeutic phage preparation tested in patients. The project began only in April 2026 and is scheduled to continue until September 2027.
The €150,000 ERC award should therefore be understood as funding for technological validation rather than deployment of an established platform. Important questions concerning capture specificity, recovery yield, preservation of infectivity, contaminant clearance, scalability and reproducibility remain to be answered experimentally.
Clinical validation is even further downstream. Demonstrating that a platform can purify bacteriophages efficiently does not establish that therapeutic products manufactured with it are safe or effective in patients. Any clinical preparation would still have to satisfy the appropriate pharmaceutical, microbiological and regulatory requirements.
The relatively small size of the project compared with large ERC Starting, Consolidator or Advanced Grants also reflects its different purpose. PhageTRAP is not intended to fund a broad five-year programme of fundamental phage biology. It is an 18-month translational project designed to determine whether a specific technological concept is sufficiently practical to justify further development, commercialization or intellectual-property protection.
That makes its outcome particularly interesting for the phage-therapy manufacturing field. A successful proof of concept could provide the basis for larger-scale engineering, partnerships with phage manufacturers or adaptation into automated screening and purification workflows.
Failure would also be scientifically informative. If recognition motifs prove too phage-specific, binding capacity is insufficient or recovery significantly damages viral infectivity, these limitations would identify where chemical capture strategies need further development.
The broader context is a phage-therapy field increasingly moving beyond questions of whether bacteriophages can kill bacteria. Attention is shifting toward the entire development chain required to turn that biology into reliable medicines: predictive host-range selection, bacterial defence profiling, physiological determinants of infection, GMP manufacturing, purification, formulation and standardized clinical testing.
PhageTRAP occupies a highly specific position within that chain. It does not attempt to discover the perfect therapeutic phage or manufacture a final clinical product. It aims to create a molecular tool that makes it easier to obtain, select and clean the phages that other programmes need.
If synthetic capture-and-release motifs can be made sufficiently selective, reversible and adaptable, the technology could reduce some of the repetitive processing currently required for every new bacteriophage. That could become particularly valuable as therapeutic programmes move toward larger libraries and increasingly personalized phage combinations.
For now, the University of Vienna project remains an experimental platform with €150,000 and 18 months to demonstrate that principle. But its target is an increasingly important bottleneck: therapeutic phages cannot reach patients simply because they kill bacteria efficiently. They also need to be isolated, selected, purified and manufactured in a form that can reliably become a medicine.
Sources :
European Commission CORDIS — PhageTRAP: A Device for Phage Capture and Release. Grant Agreement 101292808. CORDIS confirms the €150,000 EU contribution, February 23, 2026 grant signature, April 1, 2026 start and September 30, 2027 end. It describes the modular solid-support platform, synthetic capture motifs, Gram-positive and Gram-negative proof-of-concept targets, environmental phage testing, high-throughput screening and therapeutic-grade purification objectives.
https://cordis.europa.eu/project/id/101292808
University of Vienna — ERC Proof of Concept for the PhageTRAP research project, January 27, 2026. The university identifies Thomas Böttcher as project leader and describes the intended platform as a combination of synthetic chemistry and microbiology for scalable purification, high-throughput screening and rational phage selection.
https://www.univie.ac.at/en/research/prizes-and-awards/erc-grants/details/boettcher-thomas
Böttcher Laboratory, University of Vienna — ERC Proof of Concept grant, January 30, 2026. The laboratory confirms that PhageTRAP aims to create a modular platform for capturing bacteriophages.
https://boettcher-lab.univie.ac.at/erc-proof-of-concept-grant/
Vienna BioCenter — ERC Proof of Concept Grants awarded to Vienna BioCenter Researchers, January 29, 2026. Provides additional institutional description of PhageTRAP and Thomas Böttcher's research programme at the Centre for Microbiology and Environmental Systems Science.
https://www.viennabiocenter.org/about/news/erc-proof-of-concept-grants-awarded-to-vienna-biocenter-researchers/
European Commission CORDIS — CAPSID: Controlling Activity of Lysogenic Phages by Small Molecule Inducers and Dysregulators. Böttcher's earlier ERC-funded programme at the University of Vienna ran from October 2020 through September 2026 with an EU contribution of approximately €1.99 million and investigated chemical regulation of phage–microbe interactions.
https://cordis.europa.eu/project/id/865849
Oślizło A. et al. — “Purification of phage display-modified bacteriophage T4 by affinity chromatography.” BMC Biotechnology 11, 59 (2011). The study demonstrated selective affinity-resin binding and release of T4 phages carrying affinity motifs, providing earlier evidence that affinity-based phage purification is technically possible.
https://pubmed.ncbi.nlm.nih.gov/21627821/
Kabwe M. et al. — “Evaluation of effectiveness of bacteriophage purification methods.” Virology Journal (2024). The study compares endotoxin-removal strategies and illustrates the continuing need to balance contaminant reduction against preservation of phage titre. The article is available under CC BY 4.0.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11656862/
Santos A.R. et al. — “Scalable purification of bacteriophages preparations.” The study investigates anion-exchange chromatography as part of a scalable purification workflow and highlights the need to remove endotoxins, proteins and host-cell DNA from therapeutic phage preparations.
https://pubmed.ncbi.nlm.nih.gov/40154192/
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