title: Deep-Sequence Identification and Role in Virus Replication of a JC Virus Quasispecies in Patients with Progressive Multifocal Leukoencephalopathy.
abstract: JC virus (JCV) is a DNA virus causing progressive multifocal leukoencephalopathy (PML) in immunodeficient patients. In the present study, 22 genetic quasispecies with more than 1.5% variant frequency were detected in JCV genomes from six clinical samples of PML by next-generation sequencing. A mutation from A to C at nucleotide (nt) 3495 in JCV Mad1 resulting in a V-to-G amino acid substitution at amino acid (aa) position 392 of the large T antigen (TAg) was identified in all six cases of PML at 3% to 19% variant frequencies. Transfection of JCV Mad1 DNA possessing the V392G substitution in TAg into IMR-32 and human embryonic kidney 293 (HEK293) cells resulted in dramatically decreased production of JCV-encoded proteins. The virus DNA copy number was also reduced in supernatants of the mutant virus-transfected cells. Transfection of the IMR-32 and HEK293 cells with a virus genome containing a revertant mutation recovered viral production and protein expression. Cotransfection with equal amounts of wild-type genome and mutated JCV genome did not reduce the expression of viral proteins or viral replication, suggesting that the mutation did not have any dominant-negative function. Finally, immunohistochemistry demonstrated that TAg was expressed in all six pathological samples in which the quasispecies were detected. In conclusion, the V392G amino acid substitution in TAg identified frequently in PML lesions has a function in suppressing JCV replication, but the frequency of the mutation was restricted and its role in PML lesions was limited.
  
  
  OBJECTIVE
  DNA viruses generally have lower mutation frequency than RNA viruses, and the detection of quasispecies in JCV has rarely been reported. In the present study, a next-generation sequencer identified a JCV quasispecies with an amino acid substitution in the T antigen in patients with PML. In vitro studies showed that the mutation strongly repressed the expression of JC viral proteins and reduced the viral replication. However, because the frequency of the mutation was low in each case, the total expression of virus proteins was sustained in vivo. Thus, JC virus replicates in PML lesions in the presence of a mutant virus which is able to repress virus replication.
authors: Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Kenta
authors: K
authors: Takahashi
authors: Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Tsuyoshi
authors: T
authors: Sekizuka
authors: Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Hitomi
authors: H
authors: Fukumoto
authors: Department of Virology 1, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Kazuo
authors: K
authors: Nakamichi
authors: Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Tadaki
authors: T
authors: Suzuki
authors: Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Yuko
authors: Y
authors: Sato
authors: Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Hideki
authors: H
authors: Hasegawa
authors: Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Makoto
authors: M
authors: Kuroda
authors: Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan katano@nih.go.jp.
authors: Harutaka
authors: H
authors: Katano
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000957:Antigens, Viral, Tumor; D045744:Cell Line, Tumor; D056915:DNA Copy Number Variations; D004279:DNA, Viral / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D016679:Genome, Viral; D057809:HEK293 Cells; D006801:Humans; D007577:JC Virus / Q000235:genetics* / Q000378:metabolism; D007968:Leukoencephalopathy, Progressive Multifocal / Q000473:pathology / Q000821:virology*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009474:Neurons / Q000473:pathology / Q000821:virology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014162:Transfection; D014779:Virus Replication
chemical_list: D000957:Antigens, Viral, Tumor; D004279:DNA, Viral
keywords: JCV; PML; large T antigen; next-generation sequencer; progressive multifocal leukoencephalopathy; quasispecies; virus replication