By Eleanor Bradford
BBC Scotland Health Correspondent:
Dr Neil Abbot, of ME Research UK, said it was " fascinating to discover evidence of a persistent or reactivating viral infection".
"Although the cause of ME is unknown, more than half of all patients say their illness started with an infection," he said.
"The study undoubtedly adds greater scientific weight to the existence of a condition which, sadly, many still fail to acknowledge in spite of its severity."