Environment-driven active transport of influenza A virus

Influenza A virus (IAV) breaks traditional views of particles as passive diffusers or those powered by internal engines. Instead, researchers demonstrate that IAV actively navigates its surroundings through environmental manipulation, creating memory and directional cues in two and three dimensions. This process hinges on IAV's envelope proteins, hemagglutinin (HA) and neuraminidase (NA), which bind and cleave sialylated glycan receptors.

By examining the interplay between HA, NA, and receptor binding/cleavage, the study integrates theoretical models, simulations, and single-virus tracking to reveal the relationship between these interactions and macroscopic transport. As HA cleaves receptors, it dissipates chemical free energy, influencing the likelihood of re-bonding to the altered landscape while leaving a trail that shapes future interactions.

In landscapes with varied receptor densities, multivalent binding between HA and receptors directs motion towards regions with higher receptor concentration, while NA-mediated receptor destruction amplifies this tendency by enhancing the contrast experienced by HA. To validate their findings, researchers conducted experiments on artificial glycan membranes, confirming that IAV steps are indeed biased along local receptor gradients.

The implications of this research extend beyond understanding IAV's movement. The theory suggests that the variability exhibited by virions can distribute transport functions within a population, acting as a physical safeguard against complex receptor environments. Ultimately, this study establishes environment-driven active matter as a mechanism enabling motorless transport, powered and guided by the chemical modification of the surroundings.