Omics Sweep of Cat Parasite Surfaces Repurposing Targets for a Drug-Resistant Disease

A chronic, stubbornly treatable diarrhoeal disease of cats may finally have a roadmap toward better drugs. Feline tritrichomonosis, caused by the flagellated protozoan Tritrichomonas foetus, affects cats worldwide and has long relied on a single off-label therapy, the 5-nitroimidazole ronidazole. That drug carries a narrow therapeutic window, and clinical resistance has now been documented across three continents. Against this backdrop, researchers at the National Veterinary Research Institute in Puławy, Poland, have carried out an integrative bioinformatic reanalysis of the parasite’s genome and proteome, publishing their results in BMC Genomics. Their work delivers a substantially expanded and cross-validated catalogue of potential drug targets, many of which belong to protein families for which clinically advanced small-molecule inhibitors already exist.

The study represents the first comprehensive in silico drug-target prioritisation for T. foetus in roughly a decade. The previous analysis, published ten years ago, proposed 113 candidate targets based solely on homology to compounds catalogued in the ChEMBL database. Since then, both the genomic resources available for the parasite and the pharmacological landscape have changed considerably. The new work, led by Joanna Dąbrowska with colleagues Maciej Kochanowski and Jacek Sroka, set out to close that gap with a far more layered approach, drawing on multiple independent lines of evidence rather than a single homology filter.

The pipeline began with the predicted proteome of T. foetus strain K, which contains 25,030 proteins. From this starting point, the researchers applied a subtractive strategy designed to strip away anything unlikely to make a safe and effective drug target. Proteins with close counterparts in the feline host were filtered out, reducing the risk that an inhibitor would also attack the cat’s own biology. The remaining proteins were then cross-referenced against three pharmacological reference databases, which flag targets already known to be druggable, and against essential-gene resources drawn from three model eukaryotic organisms, which highlight genes that parasites of this kind cannot survive without.

A further layer of prioritisation drew on PHI-base, a curated virulence reference database that catalogues genes experimentally shown to contribute to pathogenicity in other organisms. Proteins appearing in this resource are attractive candidates because disrupting them could blunt the parasite’s ability to cause disease, not merely its survival in culture. When all of these filters were combined, the pipeline returned 433 priority candidates from strain K. To test whether the result was an artefact of one particular genome assembly, the team ran the identical pipeline on a chromosome-scale assembly of a second strain, KV-1, which yielded 436 candidates. Sixty-six percent of the candidates were recovered as reciprocal best hits between the two strains, a substantial cross-strain overlap that strengthens confidence in the robustness of the target list.

Expression data added a third dimension to the prioritisation. A candidate protein may look perfect on paper, but if the gene encoding it is silent in the disease-relevant life stage, it offers little therapeutic purchase. Using gene-level transcriptomic data from the feline isolate G10/1, the researchers found that 82.7 percent of the priority candidates were actively transcribed in that isolate, measured in transcripts per million. This high proportion of expressed targets suggests that the subtractive pipeline is not merely cataloguing genomic relics but is surfacing proteins the parasite genuinely deploys during infection of its feline host.

The most striking finding emerged when the candidates were ranked by expression level. Nine of the ten most highly expressed priority candidates belong to protein families for which clinically advanced small-molecule inhibitors are already available. These families include the molecular chaperones Hsp70 and Hsp90, the CDC48/p97 AAA+ ATPase, components of the ubiquitin-proteasome pathway, and serine/threonine kinases. Each of these protein classes has been the subject of intensive pharmaceutical development in human medicine, particularly in oncology, where inhibitors of Hsp90, p97, the proteasome, and various kinases have advanced through clinical trials or reached approval. The implication is direct: medicinal chemistry against these families is mature, and existing compounds or close analogues could be screened for activity against T. foetus without the need to invent inhibitor scaffolds from scratch.

The tenth member of that top-ten list stands out for a different reason. It is a Rab4B GTPase, a member of the broader Ras/GTPase superfamily, which is generally considered pharmacologically tractable because GTP-binding proteins have well-defined nucleotide pockets that small molecules can target. However, no Rab4B-specific inhibitor has been characterised to date. This makes the Rab4B candidate both an intriguing opportunity and an open challenge: it would require de novo inhibitor development rather than repurposing, but it sits within a protein superfamily with a long track record of successful drug discovery.

To demonstrate that the candidate list can support structure-based work, the team carried out a proof-of-concept molecular docking screen against three of the top-ranked candidates. Docking computationally fits small ligands into the three-dimensional structures of target proteins and scores the predicted binding affinity. Using a ligand library that included positive controls, negative control analogues, selective inhibitors, and natural ligand controls, each annotated with its clinical or pre-clinical development status, the researchers recovered internally consistent, structure-based affinity rankings across the three targets. The authors are careful to note that these computational results await experimental validation, but the internal consistency of the rankings suggests the protein structures and docking workflow are behaving as expected and can serve as a foundation for laboratory follow-up.

The practical significance of the work lies in the disease it addresses. Feline tritrichomonosis is a chronic large-bowel diarrhoea that persists in infected cats, and with no approved therapy, veterinarians are left using ronidazole off-label. The drug’s narrow therapeutic window means the margin between an effective dose and a toxic one is slim, and the documented spread of resistance across three continents makes the search for alternatives urgent. By identifying targets in protein families with existing clinical-grade inhibitors, the study offers what the authors describe as an immediate opportunity for drug-repurposing studies. Repurposing, in which drugs developed for one indication are tested against another, can compress the timeline and cost of drug development dramatically, because safety, pharmacokinetic, and manufacturing data for the original compounds may already exist.

The researchers have made their full candidate list and supporting data openly available as supplementary tables, including UniProt and RefSeq identifiers, locus tags, protein descriptions, Pfam and InterPro annotations, Gene Ontology terms, pathway counts, expression values, the complete docking ligand library, and the cross-strain reciprocal best hit pairs. The work was supported by the Internal Research Fund of the National Veterinary Research Institute under project F/123, and the authors acknowledge the Galaxy Europe community and the European Bioinformatics Institute for maintaining the public bioinformatic resources on which the analysis relied, including Ensembl Protists, InterProScan, and the AlphaFold Protein Structure Database. For a parasite that has received far less research attention than its importance to feline health would justify, the study provides both a starting point for experimental target validation and a template for how integrative omics can accelerate drug discovery in neglected veterinary pathogens.

Subject of Research: Integrative omics identification of drug-repurposing targets in the feline parasite Tritrichomonas foetus

Article Title: Integrative omics reveals candidate drug-repurposing targets in Tritrichomonas foetus

Article References: Dąbrowska, J., Kochanowski, M., & Sroka, J. (2026). Integrative omics reveals candidate drug-repurposing targets in Tritrichomonas foetus. BMC Genomics. https://doi.org/10.1186/s12864-026-13330-5

Image Credits: AI Generated

DOI: 10.1186/s12864-026-13330-5

Keywords: Tritrichomonas foetus, feline tritrichomonosis, drug repurposing, drug-target prioritisation, subtractive proteomics, comparative genomics, molecular docking, Hsp90, ubiquitin-proteasome pathway, kinases, Rab4B GTPase, ronidazole resistance