How Influenza's Spike Motor Works

TL;DR

This paper develops a physical model explaining how influenza virus actively moves across surfaces using spike proteins, revealing a deterministic rotary propulsion mechanism distinct from Brownian ratchets, with implications for virus behavior and nanotechnology.

Contribution

It introduces a quantitative physical model of influenza's spike-driven motility, demonstrating a self-organized rolling propulsion mechanism that operates as a macroscopic engine.

Findings

Predicts collective spike protein dynamics leading to virus propulsion

Shows the mechanism is deterministic, not fluctuation-driven

Applicable to influenza relatives and synthetic nanomachines

Abstract

While often believed to be a passive agent that merely exploits its host's metabolism, influenza virus has recently been shown to actively move across glycan-coated surfaces. This form of enzymatically driven surface motility is currently not well understood and has been loosely linked to burnt-bridge Brownian ratchet mechanisms. Starting from known properties of influenza's spike proteins, we develop a physical model that quantitatively describes the observed motility. It predicts a collectively emerging dynamics of spike proteins and surface bound ligands that combined with the virus' geometry give rise to a self-organized rolling propulsion. We show that in contrast to a Brownian ratchet, the rotary spike drive is not fluctuation driven but operates optimally as a macroscopic engine in the deterministic regime. The mechanism also applies to relatives of influenza and to man-made analogues like DNA-monowheels and should give guidelines for their optimization.