Herpesviruses and human endogenous retroviral sequences in the cerebrospinal fluid of multiple sclerosis patients

Objective To analyze the possible role of human herpesvirus ( HHVs) and human endogenous retroviruses ( HERVs) infection in multiple sclerosis ( MS) pathogenesis. Methods A total of 92 cerebrospinal fluid ( CSF) samples were collected: 48 from MS patients at the first clinically evident demyelinating event, 23 from patients with other inflammatory neurological diseases ( OINDs) and 21 from patients with other non-inflammatory neurological diseases (ONINDs). Total DNA and RNA were isolated, and the prevalences and viral loads of herpes simplex virus ( HSV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), HHV-6, HERV-H and HERV-W in the CSF of MS patients and controls were evaluated using a quantitative real-time polymerase chain reaction assay. Results (i) For HSV, 1/48 (2.1%, 86 copies/ml of CSF) MS patients and 1/23 (4.3%, 115.2 copies/ml of CSF) OIND patients ( a myelitis case) had HSV sequences in the CSF; ( ii) for EBV, only 1/48 ( 2.1%, 72 copies/ml of CSF) MS patients was positive for EBV; (iii) for HHV-6, only 5/48 (10.4%) MS patients had HHV-6 genomes in their CSF (128.1 copies/ml of CSF); (iv) we did not find any positive cases for VZV, CMV, HERV-H and HERV-W among MS patients or controls; ( v) no cases of co-infections were found; ( vi) the whole prevalence of HHVs was 7/48 (14.6%) for MS patients and 1/44 (2.3%) for controls (p=0.038). Conclusion The findings described here show that HHV infection is more frequent in the CSF of MS patients than in patients with other neurological diseases; however, only HHV-6 seems to be involved in the pathogenesis of MS in a subset of patients.