Oxford scientists watched virus-like particles build themselves by trial and error, with no blueprint

Oxford chemists have watched a single engineered virus-like particle assemble itself, tracking its mass as 60 protein units attached one step at a time. The study, published in Nature on Sept. 16, was led by Roi Asor and Philipp Kukura, and it shows that the particle finds its finished shape through repeated mistakes and retries rather than by following a plan.

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Asor, a co-lead author in Oxford’s Department of Chemistry and Kavli Institute for Nanoscience Discovery, summarized the logic in one line: “The weak interactions give the system room to make mistakes.” The paper’s name promises molecular-level observation, and that is what the data deliver, a growing particle weighed repeatedly while it is built.

Mass photometry and a video of assembly

The work, described in a University of Oxford release dated Sept. 16, combined two tools. Mass photometry, a technique developed at Oxford, measures the mass of individual molecules from the light they scatter. The team paired it with a new way of confining single molecules so they stay in view continuously. Together they let the researchers measure one growing particle again and again as protein components joined it.

That is a different kind of evidence from earlier approaches, which pieced together assembly from before-and-after snapshots or from theoretical models. Dan Loewenthal, a PhD student and co-first author, described the approach as studying assembly directly, in effect taking a video. Kukura, a professor in Oxford’s Department of Chemistry and the Kavli Institute for Nanoscience Discovery, said the method lets the team see the important intermediate structures appear and deduce a detailed model of the construction process, according to the university.

The study was published as Molecular-level observation of the self-assembly of a virus-like particle in Nature. ScienceDaily carried the story on Oct. 22 under the line Oxford scientists discover how viruses build themselves without a blueprint, which is where the no-blueprint framing comes from.

Weak bonds, stable checkpoints and a pentagon

A virus shell, or capsid, can contain tens or even thousands of protein components, and the pieces could in principle fit together in thousands of possible ways, according to a News-Medical summary of the Oxford release. Early on, the building blocks form weak, reversible bonds. Wrong arrangements simply fall apart and the pieces try again, which is the trial and error behind the finding. A capsid protects viral genetic material, so how the shell forms matters for any drug meant to disrupt it. Asor called the construction problem an extraordinary one that a virus has to solve.

Once multiple connections lock a closed structure in place, it becomes stable and acts as a checkpoint from which assembly continues. Those checkpoints narrow the many possible routes to a small set of successful ones. The first highly stable structure in the pathway is a closed pentagonal ring of five larger building blocks. After it forms, each later stable stage needs fewer additional blocks, so growth speeds up, and the earliest nucleation stage is the hardest. In physical-chemistry terms, nucleation is the slow, unlikely first step that must happen before a structure can grow quickly, and here the pentagonal ring plays that role.

A trade publication, Manufacturing Chemist, calls the work the first direct observation of individual virus-like particles assembling step by step, a claim that belongs to the publication and not to the paper. It quotes Asor saying: “That combination of trial and error followed by locking in successful structures is what makes the process so reliable.” The journal reference lists Diana Melnyk and Tiong Kit Tan among the authors alongside Asor, Loewenthal, Kukura and Tan.

Antivirals and vaccines: prospects, not results

The researchers point to possible uses. Jack Tan, a co-author at the MRC Weatherall Institute of Molecular Medicine and the CAMS-Oxford Institute, said in the Oxford release that the ability to understand these processes at the molecular level “could have important applications in vaccine development and antivirals that disrupt viral assembly.” Drugs aimed at the construction of the viral shell, and vaccines built from virus-like particles, are the two directions named.

Those applications are prospects, and none has been demonstrated. The particle in the study is engineered from 60 protein units and is not a live virus, so how closely natural viruses follow the same pathway is a question for later work. The method also depends on catching intermediate structures that are scarce and short-lived, and it works on single molecules. The researchers add that self-assembly matters well beyond viruses, since many biological structures form that way, so the same observation technique may be applied to other systems. The Oxford release names no funding sources, and the results come from a single engineered system, so repeating the observation on other particles will show how general the pathway is.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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