VP1VP4

VP1VP4 is a term used in virology to describe the interaction between two structural capsid proteins, VP1 and VP4, in picornaviruses. It refers to the contact interface or a functional association within the virion rather than a separate gene product. The term appears in structural discussions of how the outer and inner capsid components cooperate during assembly, stability, and uncoating.

In the picornavirus capsid, VP1 forms part of the external surface of the icosahedral shell, while VP4 is a smaller protein associated with the inner face of the capsid and implicated in genome release. Their interaction contributes to particle stability during maturation and plays a role in the conformational changes that occur during uncoating. The VP1–VP4 interface is thus a key component of the virion’s architecture, influencing how the particle remains intact outside the host cell and how it transitions to an uncoated state once inside.

Discovery and relevance: High-resolution structural techniques such as cryo-electron microscopy and X-ray crystallography have illuminated the contacts between VP1 and VP4 in several picornaviruses, helping to explain mechanisms of assembly and uncoating. The VP1VP4 interface is of interest because mutations at this interface can affect thermostability, receptor engagement, and genome release. As a result, researchers study this interface to inform antiviral targeting and vaccine design, aiming to disrupt critical capsid interactions or stabilize desired conformations.

Variations and research directions: While the general concept of VP1–VP4 interaction is conserved within picornaviruses, specific contact residues and binding geometries vary among genera. Ongoing work seeks to map essential contact points, understand their role across viral life cycles, and explore inhibitors that perturb VP1–VP4 contacts to block assembly or uncoating.