RNASEL and myalgic encephalomeyelitis/chronic fatigue syndrome: Regardless of which virus infection may trigger ME/CFS, specific immunological changes that CFS and viral infections have in common include altered antiviral response elements, for example, the 2-5A synthetase/ribonuclease L (RNase L) antiviral defense pathway in monocytes, which is mediated by interleukins [3,31,56], and elevated cytokine levels.