Electrostatic inactivation of RNA viruses at air-water and liquid-liquid interfaces

TL;DR

This study uses theory and simulations to reveal that electrostatic forces at air-water and liquid-liquid interfaces can inactivate RNA viruses, offering insights for designing effective disinfection strategies.

Contribution

It demonstrates that electrostatics is a general mechanism for virus inactivation at interfaces and explores how interfacial and electrostatic forces influence viral fate.

Findings

Electrostatics significantly increases free energy of viruses breaching interfaces.

Virus fate depends on the balance of interfacial and electrostatic forces.

Charge distribution in viruses like influenza and coronaviruses enables tunable inactivation.

Abstract

Understanding the interactions between viruses and surfaces or interfaces is important, as they provide the principles underpinning the cleaning and disinfection of contaminated surfaces. Yet, the physics of such interactions is currently poorly understood. For instance, there are longstanding experimental observations suggesting that the presence of air-water interfaces can generically inactivate and kill viruses, yet the mechanism underlying this phenomenon remains unknown. Here we use theory and simulations to show that electrostatics provides one such mechanism, and that this is very general. Thus, we predict that the free energy of an RNA virus should increase by several thousands of $k_BT$ as the virion breaches an air-water interface. We also show that the fate of a virus approaching a generic liquid-liquid interface depends strongly on the detailed balance between interfacial and electrostatic forces, which can be tuned, for instance, by choosing different media to contact a virus-laden respiratory droplet. We propose that these results can be used to design effective strategies for surface disinfection. Intriguingly, tunability requires electrostatic and interfacial forces to scale similarly with viral size, which naturally occurs when charges are arranged in a double-shell distribution as in RNA viruses like influenza and all coronaviruses.