Low prevalence of TT virus in the cerebrospinal fluid of viremic patients with central nervous system disorders

TT virus (TTV) is a widespread infectious agent of humans identified in 199 8. In infected individuals, TTV induces persistent viremia but its life cyc le and pathogenic potential are still poorly understood. In the present stu dy, the presence of TTV DNA in 32 consecutive paired serum and cerebrospina l fluid (CSF) samples from patients with neurological (mainly multiple scle rosis) disorders was investigated by means of a sensitive quantitative real -time PCR assay. Of the 24 patients who were found to carry TTV DNA in seru m, 3 also had detectable TTV DNA in their CSF. Two TTV positive CSF samples had markers indicative of blood contamination or a disrupted blood-brain b arrier and contained considerably lower TTV loads as compared with the corr esponding serum samples, thus suggesting that the virus they contained was of plasma origin. These findings indicated that in general TTV does not per meate effectively an intact blood-brain barrier. Furthermore, the CNS does not represent a common site of TTV replication and persistence. However, at least one exception was observed: the third TTV positive CSF sample (obtai ned from a patient with subacute dementia of unknown origin) showed no mark ers suggestive of disrupted blood-brain barrier or blood contamination and had a TTV DNA concentration similar to that found in the patient's serum. I n addition, the TTV isolates detected in the two body fluids were distinct genetically. The detection of TTV DNA in CSF is of considerable interest bu t the clinical significance remains unknown. (C) 2001 Wiley-Liss, Inc.