Vp22

VP22 is a tegument protein found in herpesviruses, most notably in herpes simplex virus type 1 (HSV-1). It is encoded by the UL49 gene and is named for its approximate molecular mass of 22 kilodaltons. The protein is a phosphoprotein that localizes to both the nucleus and the cytoplasm and is incorporated into virions during assembly.

In HSV-1, VP22 associates with other tegument proteins and the capsid, contributing to tegumentation and secondary envelopment. It is thought to participate in intracellular transport of viral components, influence viral gene expression, and modulate host cell responses. The precise functions of VP22 can vary with viral strain and experimental context; in some settings, deletion of VP22 reduces replication efficiency and spread, though the protein is not universally essential for replication in cell culture.

VP22 homologs are present in other alphaherpesviruses, where related but not identical functions are observed. The protein’s localization signals and interaction profile appear to support multiple roles in virion assembly, tegument organization, and communication with host cell pathways.

Beyond its role in viral biology, VP22 has been explored as a tool in molecular biology because of reported intercellular transfer properties, which researchers have used to deliver fusion proteins between cells in experimental systems. This potential has prompted interest in VP22 as a research tool and, in some cases, as a basis for antiviral or therapeutic strategies.