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Microtubules and intermediate filaments of herpes simplex virus infected cells
Abstract:
The fate of microtubules and of vimentin or keratin containing intermediate filaments during infection with fusion or rounding producing strains of herpes simplex virus (HSV) was investigated. Microtubules polymerize early after fusion of cells. However, they do not reconstitute 6-7 hours post infection (p.i.) after release of a colcemid block. Keratin and vimentin are maintained around the original nucleus still inside of recruited cells in the polykaryocyte. Cells of fibroblastic and epithelial origin fuse. Inside of polykaryocytes keratin or vimentin containing fibers seem to polymerize. Keratin is to be found in invaginations in the nuclei surrounded by the inner layer of the nuclear membrane. Anti-keratin antibodies specifically label HSV envelopes located in the cytoplasm or outside of the cell. Controls of the procedure allowed to exclude labelling of HSV envelopes via gpE, which represents HSV induced Fc receptors. Late stages of infected cells contain thickened and condensed keratin fibers. Conversely, vimentin fibers late after infection appear to be evenly distributed and to be thin. Microtubules decay late after infection with rounding producing strains of HSV, whereas keratin and vimentin fibers are still present late after infection.
Insights
Herpes simplex virus (HSV) infection disrupts microtubules but preserves keratin and vimentin intermediate filaments. These filaments, particularly keratin, show altered structures and localization within infected cells, even at late stages.
Area of Science:
- Cell Biology
- Virology
- Cytoskeleton Dynamics
Background:
- Herpes simplex virus (HSV) infection is known to affect cellular structures.
- The behavior of intermediate filaments like vimentin and keratin, and microtubules during viral infections is not fully understood.
Purpose of the Study:
- To investigate the fate of microtubules, vimentin, and keratin intermediate filaments during herpes simplex virus (HSV) infection.
- To determine how different strains of HSV (fusion-inducing vs. rounding-producing) impact these cytoskeletal components.
Main Methods:
- Observation of microtubule and intermediate filament organization in HSV-infected fibroblastic and epithelial cells.
- Use of colcemid to assess microtubule recovery post-infection.
- Immunofluorescence microscopy with anti-keratin and anti-vimentin antibodies.
- Control experiments to rule out non-specific antibody binding to viral envelopes.
Main Results:
- Microtubules polymerize early post-fusion but fail to reconstitute after colcemid release 6-7 hours post-infection.
- Keratin and vimentin filaments are maintained around the nucleus in polykaryocytes and appear to polymerize within them.
- Keratin localizes to nuclear invaginations, and anti-keratin antibodies specifically label HSV envelopes.
- Late-stage infection shows thickened keratin fibers and evenly distributed, thin vimentin fibers, while microtubules decay.
Conclusions:
- HSV infection significantly alters microtubule dynamics, leading to their decay.
- Keratin and vimentin intermediate filaments exhibit differential stability and reorganization during HSV infection.
- Keratin's interaction with viral envelopes suggests a potential role in viral assembly or egress.