title: Novel DNA sequence isolated from blood donors with high transaminase levels.
abstract: OBJECTIVE
  In Japan, the etiology of 10-20% of cases of acute hepatitis remains unclarified. This study was conducted to verify the agent causing non-A-E hepatitis.
  
  
  METHODS
  Serum samples from 500 blood donors with elevated alanine aminotransferase (ALT) levels were screened by polymerase chain reaction using primers constructed from conserved areas of RNA virus helicase. The sequence obtained was investigated for viral properties.
  
  
  RESULTS
  Four blood samples were found to contain a novel DNA sequence of 9496 bp, which was designated KIs-V. KIs-V was sensitive to the restriction enzyme SalI and BstXI. Rolling-circle amplification produced an excessive amount of KIs-V DNA. In sucrose density gradient ultracentrifugation, KIs-V banded at a 1.158-g/cm(3)  density. Detergent treatment increased the density of KIs-V. There was no KIs-V DNA amplification from human leukocyte DNA. Serial filtration suggested that KIs-V was included in a 30-50-nm size particle. In silico analysis revealed that KIs-V contained 13 potential genes, none of which showed homology to any viral proteins reported. One gene showed similarity to a DNA polymerase domain. Strong signals for transcription initiation and a CpG island were identified. The nucleotide composition of KIs-V showed a characteristic feature of circular DNA genomes that contain a replication origin and a terminus. In a preliminary study, KIs-V was frequently identified among hepatitis E virus antibody positive individuals with elevated ALT levels.
  
  
  CONCLUSIONS
  A new sequence KIs-V was isolated from blood donors with elevated ALT levels. It was suggested that KIs-V is a double-stranded circular DNA genome derived from a novel category of enveloped viruses.
authors: Central Blood Institute, Japanese Red Cross, Tokyo             Department of Population Genetics, National Institute of Genetics, Mishima             Saitama Blood Center, Japanese Red Cross, Saitama, Japan.
authors: Koei
authors: K
authors: Satoh
authors: Akiko
authors: A
authors: Iwata-Takakura
authors: Naoki
authors: N
authors: Osada
authors: Akira
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authors: Yoshikawa
authors: Yuji
authors: Y
authors: Hoshi
authors: Keiko
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authors: Miyakawa
authors: Yuko
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authors: Gotanda
authors: Masahiro
authors: M
authors: Satake
authors: Kenji
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authors: Tadokoro
authors: Hideaki
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authors: Mizoguchi