This preprint describes the high-resolution cryo-electron microscopy structure of Jabs, a bacteriophage that infects the multidrug-resistant human pathogen Mycobacterium abscessus. The authors report that Jabs conforms to the overall organization of a siphophage but contains several atypical structural features. Key findings include a T=9 icosahedral capsid assembled from two distinct major capsid proteins, an extensive network of ~1,700 disulfide bonds that stabilizes and covalently links virion modules, and a complex, conformationally dynamic adhesion device at the distal tail composed of multiple candidate receptor-binding proteins with carbohydrate-binding and β-sandwich domains. The work is presented as the first high-resolution structural view of a phage infecting M. abscessus and is positioned as a resource for studying phage–host interactions and for guiding phage engineering efforts. The article is a bioRxiv preprint (posted July 25, 2026, doi: https://doi.org/10.64898/2026.07.24.740622) and has not undergone peer review.
The Jabs capsid adopts a T=9 icosahedral geometry. Unusually, assembly of this capsid relies on two distinct major capsid proteins rather than a single protein forming all capsomers. One major capsid protein forms the hexons while a different major capsid protein forms the pentons. According to the authors, this represents an unprecedented capsid assembly strategy among icosahedral phages described to date. The dual-protein arrangement is highlighted as a principal architectural novelty that differentiates Jabs from more typical icosahedral phages.
A striking structural feature of the Jabs virion is an extensive network of disulfide bonds. The authors report approximately 1,700 disulfide bonds distributed throughout the particle. These covalent linkages both stabilize individual structural components and create covalent connections between different modules of the virion. Specifically, the disulfide network links the capsid, connector, tail, and adhesion device into a continuous covalently stabilized assembly. The presence of such an extensive disulfide network is emphasized as a major contributor to the overall structural integrity of the virion.
At the distal end of the tail, Jabs presents an elaborate adhesion device. The adhesion apparatus is described as conformationally dynamic and structurally elaborate compared with simpler tail fibers or spikes. Multiple protein components assemble into this distal structure, forming a multi-protein complex specialized for host recognition and binding. The reported dynamics of the adhesion device suggest the potential for structural rearrangements during host engagement, attachment, or subsequent infection steps.
The adhesion device comprises several candidate receptor-binding proteins organized into complex multidomain architectures. Among these are modules annotated as carbohydrate-binding modules and β-sandwich domains that assemble into hetero- and homotrimers. The authors note that these β-sandwich trimeric architectures resemble receptor-binding proteins previously described for phages that infect lactic acid bacteria. This structural resemblance is underscored as an example of convergent or shared design principles across phages that infect diverse bacterial hosts.
The structural characterization of Jabs provides new detail on phage architecture relevant to host recognition and particle stability. The dual major capsid protein strategy and the covalent disulfide linkage network are structural determinants that may influence assembly, stability, and resilience of the virion. The complex and potentially modular adhesion device, with multiple carbohydrate-binding and β-sandwich domains, defines a set of candidate receptor-binding elements that could mediate specific interactions with M. abscessus cell surface ligands. The authors propose that these structural observations expand understanding of phage structural diversity and supply a framework for mechanistic studies of phage–host interactions. They further suggest the structure could inform rational approaches to engineer phages for therapeutic use against multidrug-resistant mycobacterial infections.
This work is reported as a preprint on bioRxiv (posted July 25, 2026; doi: https://doi.org/10.64898/2026.07.24.740622) and has not been certified by peer review. The authors declared no competing interests and acknowledged funding from Vaincre la Mucoviscidose (RF20230503223). The abstract and article emphasize structural findings but do not report peer-reviewed experimental validation in this preprint; details beyond those summarized here were not reported in the source abstract.