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Search for human herpesvirus 6 DNA in cerebrospinal fluid from AIDS patients with progressive multifocal leukoencephalopathy

Recent studies have demonstrated a high frequency of cells containing human herpesvirus 6 (HHV6) genome in progressive multifocal leukoencephalopathy (PML) lesions, as well as coinfection of oligodendrocytes by JC virus (JCV) and HHV6, suggesting a role of HHV6 as a cofactor in the pathogenesis of PML (Blumberg et al, 2000; Mock et al, 1999). To explore the possibility that genome of HHV6 might be detected in cerebrospinal fluid (CSF) from acquired immunodeficiency syndrome (AIDS) patients with PML, we reviewed all cases of human immunodeficiency virus (HIV)–infected patients with a diagnosis of PML in whom a multiplex polymerase chain reaction (PCR) assay for herpesviruses was performed in CSF during the diagnostic work-up. This multiplex PCR assay for herpesviruses, described elsewhere (Quereda et al, 2000; Tenorio et al, 1993), may detect in a single run herpes simplex virus, cytomegalovirus, varicella-zoster virus, Epstein-Barr virus, and HHV6. Forty-one CSF specimens from 40 AIDS patients with a diagnosis of PML (Table 1) were tested for herpesviral DNA. Neuroimaging studies demonstrated in all the patients the characteristic nonenhancing demyelinating lesions without mass effect. JCV DNA was detected in CSF in 17 out of 22 patients studied by means of a multiplex PCR for polyomaviruses (Fedele et al, 1999). CSF was obtained a mean of 31 days after the onset of neurological symptoms, and a median of 62 days before death in 30 fatal cases. In none of the 41 CSF specimens was the HHV6 DNA detected by the multiplex PCR.