Herpes Simplex Virus Type 1 Immediate-Early Gene Expression Is Required for the Induction of Apoptosis in Human Epithelial HEp-2 Cells

ABSTRACT Wild-type herpes simplex virus type 1 (HSV-1) induces apoptosis in human epithelial HEp-2 cells, but infected cell proteins produced later in infection block the process from killing the cells. Thus, HSV-1 infection in the presence of the translational inhibitor cycloheximide (CHX) results in apoptosis. Our specific goal was to gain insight as to the viral feature(s) responsible for triggering apoptosis during HSV-1 infection. We now report the following. (i) No viral protein synthesis or death factor processing was detected after infection with HSV-1(HFEMtsB7) at 39.5°C; this mutant virus does not inject its virion DNA into the nucleus at this nonpermissive temperature. (ii) No death factor processing or apoptotic morphological changes were detected following infection with UV-irradiated, replication-defective viruses possessing transcriptionally active incoming VP16. (iii) Addition of the transcriptional inhibitor actinomycin D prevented death factor processing upon infection with the apoptotic, ICP27-deletion virus HSV-1(vBSΔ27). (iv) Apoptotic morphologies and death factor processing were not observed following infection with HSV-1(d109), a green fluorescent protein-expressing recombinant virus possessing deletions of all five immediate-early (IE) (or α) genes. (v) Finally, complete death factor processing was observed upon infection with the VP16 transactivation domain-mutant HSV-1(V422) in the presence of CHX. Based on these findings, we conclude that (vi) the expression of HSV-1 α/IE genes is required for the viral induction of apoptosis and (vii) the transactivation activity of VP16 is not necessary for this induction.

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Recruitment of the Transcriptional Coactivator HCF-1 to Viral Immediate-Early Promoters during Initiation of Reactivation from Latency of Herpes Simplex Virus Type 1

Journal of Virology ◽

10.1128/jvi.01115-09 ◽

2009 ◽

Vol 83 (18) ◽

pp. 9591-9595 ◽

Cited By ~ 26

Author(s):

Zackary W. Whitlow ◽

Thomas M. Kristie

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Rna Polymerase Ii ◽

Virus Type ◽

Herpes Simplex Virus Type ◽

Immediate Early ◽

Transcriptional Coactivator ◽

Simplex Virus ◽

Hsv 1

ABSTRACT The transcriptional coactivator host cell factor 1 (HCF-1) is critical for the expression of immediate-early (IE) genes of the alphaherpesviruses herpes simplex virus type 1 (HSV-1) and varicella-zoster virus. HCF-1 may also be involved in the reactivation of these viruses from latency as it is sequestered in the cytoplasm of sensory neurons but is rapidly relocalized to the nucleus upon stimulation that results in reactivation. Here, chromatin immunoprecipitation assays demonstrate that HCF-1 is recruited to IE promoters of viral genomes during the initiation of reactivation, correlating with RNA polymerase II occupancy and IE expression. The data support the model whereby HCF-1 plays a pivotal role in the reactivation of HSV-1 from latency.

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Recruitment of Herpes Simplex Virus Type 1 Immediate-Early Protein ICP0 to the Virus Particle

Journal of Virology ◽

10.1128/jvi.00126-10 ◽

2010 ◽

Vol 84 (9) ◽

pp. 4682-4696 ◽

Cited By ~ 20

Author(s):

Kevin Maringer ◽

Gillian Elliott

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Virus Type ◽

Herpes Simplex Virus Type ◽

Early Gene ◽

Immediate Early ◽

Independent Manner ◽

Early Protein ◽

Simplex Virus

ABSTRACT Although the herpes simplex virus type 1 (HSV-1) tegument is comprised of a large number of viral and cellular proteins, how and where in the cell these proteins are recruited into the virus structure is poorly understood. We have shown previously that the immediate-early gene product ICP0 is packaged by a mechanism dependent on the major tegument protein VP22, while others have shown a requirement for ICP27. We now extend our studies to show that ICP0 packaging correlates directly with the ability of ICP0 to complex with VP22 in infected cells. ICP27 is not, however, present in this VP22-ICP0 complex but is packaged into the virion in a VP22- and ICP0-independent manner. Biochemical fractionation of virions indicated that ICP0 associates tightly with the virus capsid, but intranuclear capsids contained no detectable ICP0. The RING finger domain of ICP0 and the N terminus of VP22 were both shown to be essential but not sufficient for ICP0 packaging and complex formation. Strikingly, however, the N-terminal region of VP22, while unable to form a complex with ICP0, inhibited its translocation from the nucleus to the cytoplasm. PML degradation by ICP0 was efficient in cells infected with this VP22 mutant virus, confirming that ICP0 retains activity. Hence, we would suggest that VP22 is an important molecular partner of ICP0 that controls at least one of its activities: its assembly into the virion. Moreover, we propose that the pathway by which VP22 recruits ICP0 to the virion may begin in the nucleus prior to ICP0 translocation to its final site of assembly in the cytoplasm.

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