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

Abstract

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.