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Expression of Oncogenic Alleles Induces Multiple Blocks to Human Cytomegalovirus Infection.
J Virol. 2016 May; 90(9):4346-4356.JV

Abstract

In contrast to many viruses, human cytomegalovirus (HCMV) is unable to productively infect most cancer-derived cell lines. The mechanisms of this restriction are unclear. To explore this issue, we tested whether defined oncogenic alleles, including the simian virus 40 (SV40) T antigen (TAg) and oncogenic H-Ras, inhibit HCMV infection. We found that expression of SV40 TAg blocks HCMV infection in human fibroblasts, whereas the replication of a related herpesvirus, herpes simplex virus 1 (HSV-1), was not impacted. The earliest restriction of HCMV infection involves a block of viral entry, as TAg expression prevented the nuclear delivery of viral DNA and pp65. Subsequently, we found that TAg expression reduces the abundance of platelet-derived growth factor receptor α (PDGFRα), a host protein important for HCMV entry. Viral entry into TAg-immortalized fibroblasts could largely be rescued by PDGFRα overexpression. Similarly, PDGFRα overexpression in HeLa cells markedly increased the levels of HCMV gene expression and DNA replication. However, the robust production of viral progeny was not restored by PDGFRα overexpression in either HeLa cells or TAg-immortalized fibroblasts, suggesting additional restrictions associated with transformation and TAg expression. In TAg-expressing fibroblasts, expression of the immediate early 2 (IE2) protein was not rescued to the same extent as that of the immediate early 1 (IE1) protein, suggesting that TAg expression impacts the accumulation of major immediate early (MIE) transcripts. Transduction of IE2 largely rescued HCMV gene expression in TAg-expressing fibroblasts but did not rescue the production of infectious virions. Collectively, our data indicate that oncogenic alleles induce multiple restrictions to HCMV replication.

IMPORTANCE

HCMV cannot replicate in most cancerous cells, yet the causes of this restriction are not clear. The mechanisms that restrict viral replication in cancerous cells represent viral vulnerabilities that can potentially be exploited therapeutically in other contexts. Here we found that SV40 T antigen-mediated transformation inhibits HCMV infection at multiple points in the viral life cycle, including through inhibition of proper viral entry, normal expression of immediate early genes, and viral DNA replication. Our results suggest that the SV40 T antigen could be a valuable tool to dissect cellular activities that are important for successful infection, thereby potentially informing novel antiviral development strategies. This is an important consideration, given that HCMV is a leading cause of birth defects and causes severe infection in immunocompromised individuals.

Authors+Show Affiliations

Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, USA.Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, USA.Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, USA josh.munger@rochester.edu.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

26889030

Citation

Xu, Shihao, et al. "Expression of Oncogenic Alleles Induces Multiple Blocks to Human Cytomegalovirus Infection." Journal of Virology, vol. 90, no. 9, 2016, pp. 4346-4356.
Xu S, Schafer X, Munger J. Expression of Oncogenic Alleles Induces Multiple Blocks to Human Cytomegalovirus Infection. J Virol. 2016;90(9):4346-4356.
Xu, S., Schafer, X., & Munger, J. (2016). Expression of Oncogenic Alleles Induces Multiple Blocks to Human Cytomegalovirus Infection. Journal of Virology, 90(9), 4346-4356. https://doi.org/10.1128/JVI.00179-16
Xu S, Schafer X, Munger J. Expression of Oncogenic Alleles Induces Multiple Blocks to Human Cytomegalovirus Infection. J Virol. 2016;90(9):4346-4356. PubMed PMID: 26889030.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Expression of Oncogenic Alleles Induces Multiple Blocks to Human Cytomegalovirus Infection. AU - Xu,Shihao, AU - Schafer,Xenia, AU - Munger,Joshua, Y1 - 2016/04/14/ PY - 2016/01/29/received PY - 2016/02/08/accepted PY - 2016/2/19/entrez PY - 2016/2/19/pubmed PY - 2016/8/25/medline SP - 4346 EP - 4356 JF - Journal of virology JO - J Virol VL - 90 IS - 9 N2 - UNLABELLED: In contrast to many viruses, human cytomegalovirus (HCMV) is unable to productively infect most cancer-derived cell lines. The mechanisms of this restriction are unclear. To explore this issue, we tested whether defined oncogenic alleles, including the simian virus 40 (SV40) T antigen (TAg) and oncogenic H-Ras, inhibit HCMV infection. We found that expression of SV40 TAg blocks HCMV infection in human fibroblasts, whereas the replication of a related herpesvirus, herpes simplex virus 1 (HSV-1), was not impacted. The earliest restriction of HCMV infection involves a block of viral entry, as TAg expression prevented the nuclear delivery of viral DNA and pp65. Subsequently, we found that TAg expression reduces the abundance of platelet-derived growth factor receptor α (PDGFRα), a host protein important for HCMV entry. Viral entry into TAg-immortalized fibroblasts could largely be rescued by PDGFRα overexpression. Similarly, PDGFRα overexpression in HeLa cells markedly increased the levels of HCMV gene expression and DNA replication. However, the robust production of viral progeny was not restored by PDGFRα overexpression in either HeLa cells or TAg-immortalized fibroblasts, suggesting additional restrictions associated with transformation and TAg expression. In TAg-expressing fibroblasts, expression of the immediate early 2 (IE2) protein was not rescued to the same extent as that of the immediate early 1 (IE1) protein, suggesting that TAg expression impacts the accumulation of major immediate early (MIE) transcripts. Transduction of IE2 largely rescued HCMV gene expression in TAg-expressing fibroblasts but did not rescue the production of infectious virions. Collectively, our data indicate that oncogenic alleles induce multiple restrictions to HCMV replication. IMPORTANCE: HCMV cannot replicate in most cancerous cells, yet the causes of this restriction are not clear. The mechanisms that restrict viral replication in cancerous cells represent viral vulnerabilities that can potentially be exploited therapeutically in other contexts. Here we found that SV40 T antigen-mediated transformation inhibits HCMV infection at multiple points in the viral life cycle, including through inhibition of proper viral entry, normal expression of immediate early genes, and viral DNA replication. Our results suggest that the SV40 T antigen could be a valuable tool to dissect cellular activities that are important for successful infection, thereby potentially informing novel antiviral development strategies. This is an important consideration, given that HCMV is a leading cause of birth defects and causes severe infection in immunocompromised individuals. SN - 1098-5514 UR - https://www.unboundmedicine.com/medline/citation/26889030/Expression_of_Oncogenic_Alleles_Induces_Multiple_Blocks_to_Human_Cytomegalovirus_Infection_ DB - PRIME DP - Unbound Medicine ER -