Multiple Sclerosis, 1 February 2003, vol. 9, no. 1, pp. 6-15(10)
Christensen T.; Sørensen P.; Hansen H.; Møller-Larsen A.
 Department of Medical Microbiology and Immunology, University of Aarhus, DK-8000 Aarhus C, Denmark  Biotechnological Institute, Kogle Alle 2, DK-2970 Hørsholm, Denmark  Department of Neurology, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
The human endogenous retrovirus HERV-H is associated with multiple sclerosis (MS).
Previously performed reverse transcriptase polymerase chain reactions (RT-PCR) on virion-RNA demonstrated sequence variants of the HERV-H family located in the particulate fraction of MS patient plasma samples and not in controls.
In this study a significantly elevated level of antibodies towards peptides derived from HERV-H/RG H-2 DNA sequences in serum and cerebrospinal fluid (CSF) from MS patients is demonstrated.
Further, Wistar rats immunized with purified virions develop a specific serologic response, indicating that some virion proteins are encoded by HERV-Hrelated sequences.
Also shown is that in RNA from blood cells, a HERV-H protease-env splice variant can be found together with an env splice variant in about 40% of MS patients but only in 10% of controls.
The results substantiate the association between activated HERV-H and MS, but a causal relationship is yet to be demonstrated.
HERV-H could represent a causal factor either by eliciting an autoimmune response or through the pathogenic potential of the retrovirus itself.