ERVW-1 and myalgic encephalomeyelitis/chronic fatigue syndrome: Two non-nested primer sets developed by Lombardi et al. were shown to be capable of detecting XMRV gag and env in the PBMCs of chronic fatigue syndrome patients, whereas a nested PCR assay developed in our laboratory had been used to detect XMRV env in the prostatic tissue of prostate cancer patients [2], [36].