Nuclear transport of human cytomegalovirus tegument protein pp65 through nucleoplasmic reticulum

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Maysa Azzeh - , Touro College of Osteopathic Medicine, New York (Joint first author)
  • Mark F. Santos - , Touro University - Nevada (Joint first author)
  • Alexandra M. K. Yokomizo - , Touro University - Nevada (Author)
  • Victoria Cha - , Touro University - Nevada (Author)
  • Denis Corbeil - , Research Group Tissue Engineering, Tissue Engineering (Research Group) (Author)
  • Aurelio Lorico - , Touro University - Nevada (Last author)

Abstract

Human cytomegalovirus (HCMV) is a widespread beta-herpesvirus that establishes lifelong infection and can cause severe disease in immunocompromised individuals as well as congenital abnormalities. While HCMV entry into fibroblasts is classically described as plasma membrane fusion, accumulating evidence indicates that a fraction of virions undergo endocytic uptake, notably via macropinocytosis, and traffic through the endosomal system. However, the mechanisms by which internalized viral components reach the nucleus are still being elucidated. Here, we investigated whether HCMV exploits type II nuclear envelope invaginations (NEIs), rare and discrete folds of the nuclear membrane that extend into the nucleoplasm, and the associated VAP-A–ORP3–Rab7 (VOR) complex to mediate nuclear delivery of viral components, a mechanism previously described for HIV-1. Using primary human foreskin fibroblasts (HFFs), we tracked the tegument protein pp65 and immediate-early proteins IE1/2 during early infection. We show that HCMV infection induces a rapid increase in NEI formation within the first hour of infection, accompanied by the accumulation of pp65 within Rab7 ⁺ endosomal structures that localize to NEIs. Pharmacological inhibition of the VOR complex with an ORP3-targeting drug significantly reduced NEI formation, decreased the association of pp65 with NEIs, and impaired its nuclear accumulation by approximately 2.5-fold. In contrast, inhibition of this pathway did not affect immediate-early gene expression at 24 hours post-infection. Functionally, disruption of the VOR complex resulted in a 3-fold reduction in viral replication, highlighting the contribution of this pathway to efficient infection. Together, these findings support a model in which HCMV tegument proteins, but not the viral genome, access the nucleus via a NEI/VOR-dependent trafficking route. This work identifies a previously unrecognized nuclear delivery pathway exploited by HCMV and suggests that targeting nuclear–endosomal communication may represent a novel antiviral strategy.

Details

Original languageEnglish
Article numbere1014224
Number of pages13
JournalPLoS Pathogens
Volume22
Issue number5
Publication statusPublished - 18 May 2026
Peer-reviewedYes

External IDs

Scopus 105039508478

Keywords

Keywords

  • VOR complex, Cytomegalovirus, tegument protein, nuclear transport