Phosphorylation of Herpes Simplex Virus 1 dUTPase Regulates Viral Virulence and Genome Integrity by Compensating for Low Cellular dUTPase Activity in the Central Nervous System

Abstract

A mutation in herpes simplex virus 1 dUTPase (vdUTPase), which precluded its phosphorylation at Ser-187, decreased viral neurovirulence and increased mutation frequency in progeny virus genomes in the brains of mice where endogenous cellular dUTPase activity was relatively low, and overexpression of cellular dUTPase restored viral neurovirulence and mutation frequency altered by the mutation. Thus, phosphorylation of vdUTPase appeared to regulate viral virulence and genome integrity by compensating for low cellular dUTPase activity in vivo. IMPORTANCEMany DNA viruses encode a homolog of host cell dUTPases, which are known to function in accurate replication of cellular DNA genomes. The viral dUTPase activity has long been assumed to play a role in viral replication by preventing mutations in progeny virus genomes if cellular dUTPase activity was not sufficient. Here, we showed that a mutation in herpes simplex virus 1 dUTPase, which precluded its phosphorylation at Ser-187 and reduced its activity, decreased viral neurovirulence and increased mutation frequency in progeny virus genomes in the brains of mice where endogenous cellular dUTPase activity was relatively low. In contrast, overexpression of cellular dUTPase restored viral neurovirulence and mutation frequency altered by the mutation in the brains of mice. This is the first report, to our knowledge, directly showing that viral dUTPase activity regulates viral genome integrity and pathogenicity by compensating for insufficient cellular dUTPase activity in vivo. Preserving the integrity of their genetic information during genome replication is of vital importance for all organisms. Noncanonical nucleotides are constantly generated during nucleotide metabolism, and their misincorporation into the genome during replication may result in increased mutagenesis and overload of the DNA excision repair system, leading to multiple DNA strand breaks and cell death (1, 2). The most common noncanonical nucleoside triphosphate is dUTP, which is continuously produced in the pyrimidine biosynthesis pathway by phosphorylation of dUDP or deamination of dCTP (1, 3). dUTPase catalyzes dUTP cleavage to dUMP and pyrophosphate, thereby reducing misincorporation of dUTP into the genome (4, 5). In addition, dUTPase also plays a role in providing a substrate for thymidylate synthase, which converts dUMP to TMP, a major biosynthetic pathway for TTP (6-8). Interestingly, a number of viruses, including herpesviruses, poxviruses, adenoviruses, D-type retroviruses, and African swine fever virus (ASFV), encode their own dUTPases, suggesting the importance of dUTPases in the life cycles of these viruses (4, 9-11).In this study, we focused on the dUTPase encoded by herpes simplex virus 1 (HSV-1), one of the best-studied members of the Herpesviridae family, which causes a variety of diseases such as mucocutaneous diseases, keratitis, skin diseases, and encephalitis (12). HSV-1 dUTPase (vdUTPase) is encoded by the UL50 gene and is conserved throughout the Herpesviridae family (13,1...

p53 Is a Host Cell Regulator during Herpes Simplex Encephalitis

“…2). We note that an approximately 3-fold difference in the level of HSV-1 replication in the brains of mice has been reported to lead to significant changes in the survival rates of mice (19,23,24).…”

“…All animal experiments were carried out in accordance with the Guidelines for Proper Conduct of Animal Experiments of the Science Council of Japan (20). The protocol was approved by the Institutional Animal Care and Use Committee, Institute of Medical Science, the University of Tokyo (IACUC protocol approval [19][20][21][22][23][24][25][26].…”

Targeting Nucleotide Biosynthesis: A Strategy for Improving the Oncolytic Potential of DNA Viruses

“…Herpes simplex virus-1 dUTPase mutants also show decreased neurovirulence and exhibit defects in exit from latency ( 250 , 251 ). The need for a functional dUTPase appears to be cell type or tissue dependent and is likely affected by the availability of cellular dUTPase.…”

“…These defects can be complemented by human dUTPase, either overexpressed by the host cell or encoded by the virus ( 252 ). The dUTPase also helps maintain the integrity of the virus genome, as dUTPase mutants isolated from brains of infected mice exhibited greater numbers of mutations per genome than wild-type viruses ( 251 ).…”

Genômica, evolução e caracterização funcional de genes de baculovírus

“…This difference in migration could be related to a type of post-translational modification such as phosphorylation. Herpes simplex virus 1 (HSV-1) dUTPase phosphorylation regulates viral virulence and genome integrity by compensating for the low cellular dUTPase activity in the central nervous system (Kato et al, 2015). We found also that HAPelu112 and HA-Erel005 presented different patterns of cytolocalization upon infection progression.…”