Shape of coronavirus can tell how quickly virus will spread, study claims

coronavirus particles are breathed, they move around within the passages in the nose and lungs. But, the scientists modelled a specific form of movement known as rotational diffusivity, which controls the pace at which particles rotate as they move through the fluid (in the case of the coronavirus, droplets of saliva).

Smoother and more hydrodynamic particles experience less drag resistance from the fluid and rotate more quickly. "If the particles rotate too quickly, they may not spend enough time interacting with the cell to infect it, and if they rotate too slowly, they may not be able to engage in the required way," Professor Eliot Fried, head of OIST's Mechanics and Materials Unit explained.

The scientists modelled both prolate and oblate ellipsoids of revolution in their study. These shapes differ from spheres (which have three axes of equal length).

A prolate shape extends into a rod-like shape, whilst oblate shapes squash into coin-like shapes. The scientists simplified their model of the spike proteins, with each spike protein represented by a single sphere on the surface of the ellipsoids. "We then figured out the arrangement of the spikes on the surface of each ellipsoidal form by assuming they all have the same charge," Dr Vikash Chaurasia, a postdoctoral researcher in the OIST Mechanics and Materials Unit, noted. "Identical charge spikes reject each other and prefer to remain as far apart as feasible." As a result, they are equally distributed around the particle, minimising this repulsion." In their model, the researchers found that the more a particle differs from a spherical shape, the slower it rotates.