title: Detection of human herpesviruses 6 and 7 genomic sequences in brain tumours.
abstract: BACKGROUND
  Human herpesviruses 6 and 7 (HHV-6, HHV-7) are ubiquitous, with primary infection occurring early in life followed by persistence, which may involve neural tissue. While HHV-6 and HHV-7 are predominantly T lymphotropic, the extent of tissue tropism in persistent infection is not known.
  
  
  OBJECTIVE
  To investigate neuropersistence and the role of HHV-6 and HHV-7 in brain tumorigenesis.
  
  
  METHODS
  Nested polymerase chain reaction was used to detect HHV-6 and HHV-7 genomic sequences in preparations of total DNA extracted from 98 formalin fixed, paraffin embedded primary brain tumours. HHV-6 detected was further characterized into variants A and B by restriction fragment length analysis.
  
  
  RESULTS
  HHV-6 was detected in 8.2% of cases and HHV-7 in 14.3% (14/98). None of the positive samples contained both viruses. Among the eight HHV-6 positive tumours, three harboured variant A and five variant B. Four of the five ependymomas studied contained viral DNA. Otherwise, both HHV-6 and HHV-7 were present at similar low frequencies in most of the tumour types investigated.
  
  
  CONCLUSIONS
  The findings do not support an aetiological role of HHV-6 and HHV-7 in primary brain tumour, but they suggest that HHV-6 and HHV-7 are neurotropic in vivo and that the central nervous system seems to be one of the reservoirs for persistent infection.
authors.affiliation: Department of Microbiology, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, China. paulkschan@cuhk.edu.hk
authors.forename: P K
authors.initials: PK
authors.lastname: Chan
authors.forename: H K
authors.initials: HK
authors.lastname: Ng
authors.forename: A F
authors.initials: AF
authors.lastname: Cheng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000032:analysis*; D005260:Female; D015654:Herpesvirus 6, Human / Q000302:isolation & purification*; D016199:Herpesvirus 7, Human / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction
chemical_list: D004279:DNA, Viral