Prevalence and distribution of human herpesvirus 7 in normal brain

Although it has been recognised that human herpesvirus 7 (HHV-7) establishe s latent infection in CD4(+) T lymphocytes and productive infection in sali vary glands, recent data suggest that its in vivo tropism may be more wides pread. In this study, the prevalence and distribution of HHV-7 in brain tis sues of 30 consecutive post-mortems were examined by nested polymerase chai n reaction. For each postmortem, 10 fresh autopsy tissue samples were colle cted respectively from the cerebellum, frontal, temporal, parietal, and occ ipital robes of both cerebral hemispheres. These patients were aged from 20 -95 years (mean = 61.4, SD = 20.2) with a male:female ratio of 2:1. Three p atients died of intracranial haemorrhage, the others died of causes unrelat ed to the central nervous system. Overall, 5% (15/300) of the brain tissue samples were positive for HHV-7 DNA. The positive rates with respect to ana tomical positions were similar (0-3/30). When analysed by patient, 36.7% (1 1/30) were HHV-7 DNA positive. The viral DNA-positive and -negative groups did not show a significant difference in gender or age distribution. The ma jority (81.8%) of viral DNA-positive patients had HHV-7 DNA detected at onl y one anatomical position; only two patients had viral DNA detected simulta neously at three anatomical sites. These results suggest that HHV-7 persist s in brain tissues of a substantial proportion of the adult population, and in most individuals, its distribution is probably confined to one site rat her than pervasive. Further studies to elucidate the role of this ubiquitou s virus in neuropathology are warranted. J. Med. Virol. 62: 345-348, 2000. (C) 2000 Wiley-Liss, Inc.