scholarly journals The Epstein-Barr Virus Thymidine Kinase Does Not Phosphorylate Ganciclovir or Acyclovir and Demonstrates a Narrow Substrate Specificity Compared to the Herpes Simplex Virus Type 1 Thymidine Kinase

1998 ◽  
Vol 42 (11) ◽  
pp. 2923-2931 ◽  
Author(s):  
Erik A. Gustafson ◽  
Antoinette C. Chillemi ◽  
David R. Sage ◽  
Joyce D. Fingeroth
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Substrate Specificity ◽  
Thymidine Kinase ◽  
Epstein Barr Virus ◽  
Barr Virus ◽  
Epstein Barr ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT The Epstein-Barr virus (EBV) thymidine kinase (TK) was expressed in mammalian 143B TK− cells to investigate its substrate specificity. The herpes simplex virus type 1 (HSV-1) TK was similarly expressed for comparison. Both viral TKs conferred a TK+ phenotype on 143B TK− cells. The nucleoside analog ganciclovir (GCV) did not affect the growth of 143B EBV TK or 143B TK− cells but effectively killed 143B HSV-1 TK cells. Furthermore, lysates of 143B EBV TK cells could not phosphorylate GCV, which was confirmed by high-performance liquid chromatography. EBV TK, HSV-1 TK, and EBV TK N−, a truncated EBV TK missing 243 N-terminal amino acids, were purified as fusion proteins expressed in bacteria, and all had TK activity. In addition, EBV TK was observed to have a thymidylate kinase activity but could not phosphorylate GCV, acyclovir, or 2′-deoxycytidine. In competition assays, only nucleoside analogs of thymidine significantly inhibited thymidine phosphorylation by EBV TK, with the following rank order: 5-bromodeoxyuridine > zidovudine > stavudine > sorivudine. These results demonstrate that EBV TK substrate specificity is narrower than those of alphaherpesvirus TKs and that thymidine analogs may be the most suitable nucleoside antivirals to target the enzyme. Clinical implications for gammaherpesviruses are discussed.

scholarly journals The Epstein-Barr Virus SM Protein Is Functionally Similar to ICP27 from Herpes Simplex Virus in Viral Infections

2002 ◽  
Vol 76 (18) ◽  
pp. 9420-9433 ◽  
Author(s):  
Julie L. Boyer ◽  
Sankar Swaminathan ◽  
Saul J. Silverstein
Keyword(s):  
Gene Expression ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Epstein Barr Virus ◽  
Common Mechanism ◽  
Barr Virus ◽  
Epstein Barr ◽  
Simplex Virus ◽  
Sm Protein ◽  
Hsv 1

ABSTRACT The herpes simplex virus type 1 (HSV-1) ICP27 protein is an essential RNA-binding protein that shuttles between the nucleus and cytoplasm to increase the cytoplasmic accumulation of viral late mRNAs. ICP27 homologs have been identified in each of the herpesvirus subfamilies, and accumulating evidence indicates that homologs from the gammaherpesvirus subfamily function similarly to ICP27. In particular, the Epstein-Barr virus (EBV) SM protein posttranscriptionally regulates gene expression, binds RNA in vitro and in vivo, and shuttles between the nucleus and cytoplasm. To determine if these two proteins function through a common mechanism, the ability of EBV SM to complement the growth defect of an HSV-1 ICP27-null virus was examined in a transient-expression assay. ICP27 stimulated the growth of the null mutant more efficiently than did SM, but the ability of SM to compensate for the ICP27 defects suggests conservation of common functions. To assay for complementation in the context of a viral infection, the growth properties of an HSV recombinant expressing SM in an ICP27-null background were analyzed. SM stimulated growth of the recombinant, although this growth was reduced by comparison to that of an ICP27-expressing virus. By contrast, an HSV recombinant expressing an SM mutant allele defective for transactivation activity and nucleocytoplasmic shuttling did not grow at all. These results suggest that SM and ICP27 may regulate gene expression through a common pathway that is evolutionarily conserved in herpesviruses.

scholarly journals Antiherpesvirus Activities of Two Novel 4′-Thiothymidine Derivatives, KAY-2-41 and KAH-39-149, Are Dependent on Viral and Cellular Thymidine Kinases

2014 ◽  
Vol 58 (8) ◽  
pp. 4328-4340 ◽  
Author(s):  
Natacha Coen ◽  
Sophie Duraffour ◽  
Kazuhiro Haraguchi ◽  
Jan Balzarini ◽  
Joost J. van den Oord ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Antiviral Activity ◽  
Epstein Barr Virus ◽  
Varicella Zoster ◽  
Barr Virus ◽  
Epstein Barr ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACTThe emergence of drug-resistant herpesviruses represents a significant problem in clinical practice, primarily in immunocompromised patients. Furthermore, effective antiviral therapies against gammaherpesvirus-associated diseases are lacking. Here, we present two thiothymidine derivatives, KAY-2-41 and KAH-39-149, with different spectra of antiviral activity from those of the reference antiherpetic drugs, showing inhibitory activities against herpes simplex virus, varicella-zoster virus (VZV), and particularly against Epstein-Barr virus, with high selectivityin vitro. While KAY-2-41- and KAH-39-149-resistant herpesviruses were found to harbor mutations in the viral thymidine kinase (TK), these mutations conferred only low levels of resistance to these drugs but high levels to other TK-dependent drugs. Also, antiviral assays in HeLa TK-deficient cells showed a lack of KAY-2-41 and KAH-39-149 activities against herpes simplex virus 1 (HSV-1) and HSV-2 TK-deficient mutants. Furthermore, enzymatic TK assays showed the ability of HSV-1 TK, VZV TK, and cellular TK1 and TK2 to recognize and phosphorylate KAY-2-41 and KAH-39-149. These results demonstrate that the compounds depend on both viral and host TKs to exert antiviral activity. Additionally, the antiviral efficacy of KAH-39-149 proved to be superior to that of KAY-2-41 in a mouse model of gammaherpesvirus infection, highlighting the potential of this class of antiviral agents for further development as selective therapeutics against Epstein-Barr virus.

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