In early papers on CFS, it was noted that EBNA1 antibody levels tended to be low relative to the levels of viral capsid antigens (VCA, a term stemming from the time of immunofluorescence diagnosis, including capsid antigens p18 and p23, and glycoprotein gp125) in sera from CFS patients relative to those of healthy controls (49). This evidence concerns the gene ART4 and myalgic encephalomeyelitis/chronic fatigue syndrome.