richvank - The retroviruses Will you please comment on the newly discovered MLV-related retroviruses in CFS patients, and what relationship they might have to the other infectious pathogens you have found in CFS. Thanks. Rich Van Konynenburg Reply: Hi Rich, The newly evolving field of human gamma retroviruses (HGV), also called XMRV , and chronic illnesses like CFS/FMS is fascinating. This type of virus has now been found at high incidence in some but not all studies on CFS patients. There may be technical reasons why some groups have not found these infections, but the field is new and in constant flux. My guess is that similar to other related retroviruses the HGV may cause changes in our immune systems rather than directly causing the most obvious signs and symptoms associated with CFS. Their effect may thus be indirect, just like the HIV-1 retrovirus causing immune suppression in AIDS rather than directly causing the symptoms of AIDS. Thus HGV may set up patients for other opportunistic infections, such as Mycoplasma, Chlamydia, Borrelia, CMV, HHV6 and other bacteria and viruses that actually cause most CFS symptoms. This is why patients who have these other infections, such as bacterial infections, benefit from their specific treatment in the absence of anti-viral treatment. This would not occur if the symptoms were entirely caused by a retrovirus. Thus I predict that anti-retrovirus treatment will not eliminate most symptoms in CFS patients, because they are more likely caused by other infections. However, modulating immune responses by suppressing viruses that could affect immune systems could have some positive effects. Eventually this will all be worked out, and we will find out what role retroviruses, along with other bacteria and viruses, play in chronic illnesses like CFS and FMS.