Intermittent bulk release of human cytomegalovirus

ABSTRACT: Human Cytomegalovirus (HCMV) significantly remodels host cell processes and membranes to enable effective production of virus progeny. Nascent capsids exit the nucleus and undergo a final morphogenesis process in the cytoplasm where they associate with tegument and membranes. During this process called secondary envelopment, fully assembled virions are formed which are wrapped inside of host vesicles. Both the origin of the receiving membrane as well as the dynamic organization of the envelopment and exocytosis process are not well understood. Enveloped virus particles can be both found individually wrapped in small vesicles but also as accumulations in multivesicular bodies (MVBs). While individually wrapped particles are believed to exit the cell by exocytosis, it is unclear if particles in MVBs ever leave the cell or are actually targeted for lysosomal degradation. Using a novel correlative light and electron microscopy workflow that allows three-dimensional imaging of whole cells, we present evidence that HCMV capsids can bud into MVBs, generating large intracellular accumulations of enveloped virions. Immunofluorescence and fusion assays suggest that these MVBs are positive for markers of the exosomal pathway. Time-lapse as well as functional live-cell imaging showed that MVBs fuse with the plasma membrane and release patch-like accumulations of virus particles. Our data suggests a so far undescribed envelopment and exocytosis pathway of HCMV, possibly involving the late-endosome/exosome pathway, leading to the intermittent bulk release of virus particles.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Human Cytomegalovirus (hhv-5) (human Herpesvirus 5)

TISSUE(S): Cell Culture, Fibroblast

DISEASE(S): Human Cytomegalovirus Infection

SUBMITTER: Hannah Britt  

LAB HEAD: Konstantinos Thalassinos

PROVIDER: PXD023444 | Pride | 2022-06-23

REPOSITORIES: Pride