ERVW-1 and myeloid sarcoma: The growing link between a HERV-W env gene and MS was highlighted when the Italian group – who had earlier confirmed a link between detection of MSRV in CSF on first presentation with eventual poorer prognosis – now showed that the measurable viral load of MSRV in the blood and cerebrospinal fluid of MS patients correlated closely with clinical activity score, stage and progression of MS.