Frederic Beseme

Development of a pan-retrovirus detection system for multiple sclerosis studies

Introduction ‐ Although recent claims implicating HTLV‐1 in multiple sclerosis (MS) have been refuted, several reports suggest that another, hitherto uncharacterised, retrovirus may be involved. We have developed and applied a novel PCR‐based strategy to explore this possibility. Methods ‐ Degenerate oligonucleotides were used in a semi‐nested format to amplify, from reverse‐transcribed RNA, a region of the pol gene which is well conserved amongst all known retroviruses. Results ‐ The ‘pan‐retrovirus’ detection system was shown to be capable of detecting diverse retroviruses including human lentivirus, human oncovirus, simian D‐type virus and murine oncovirus. The ‘pan‐retrovirus’ technique identified a novel retroviral sequence, designated MSRV‐cpol, in the serum of an MS patient and also in purified virions from MS patient‐derived tissue cultures. Sequence comparisons suggest that in the pol gene MSRV is related (˜75% homology) to the endogenous retroviral element ERV9. Conclusion ‐ These findings lend further support to the concept of retroviral involvement in MS.

Cell cultures and associated retroviruses in multiple sclerosis

Retroviral particles associated with reverse transcriptase (RT) activity in cell‐cultures from MS patients have been reported by different groups. Cell‐cultures have been used for the study and characterization of the corresponding retroviral genome which we have shown is related to ERV9 in the pol region. Previously unpublished details of a study with monocyte cultures are presented together with observations on leptomeningeal and choroid‐plexus cultures. The generation of self‐transformed cultures after inhibition of interferon, followed by the loss of retroviral expression and recurrent apoptosis, is analyzed. Retroviral particles with RT‐activity are produced in monocyte cultures with an apparent correlation with MS disease activity. However, though leptomeningeal and choroid plexus cells from MS can be passaged for a limited period, their evolution in vitro is not compatible with stable retroviral expression. These culture limitations greatly hampered progress on the elucidation of the retroviral genome sequence.