It was discovered that the drug Raltegravir (Isentress) is effective against all herpesviruses through a different mechanism than that of HIV. As it turns out, all Herpesviruses (HHV-1, HHV-2, Eppstein-Barr virus, Cytomegalovirus, HHV-8) contain the UL89 protein, which is responsible for DNA maturation. Without it, the virus cannot leave the cell to continue infection. This discovery will lead to the discovery of a class of safer drugs to treat herpesviral infections. For CFS patients, it provides a one-two punch, knocking out XMRV and Herpesvirus co-infections.
Previously, certain drugs against herpesviruses were trialled in CFS patients with only small improvements at best. The drawback to the current generation of drugs are that they are fraught with side effects. Foscarnet is extremely nephrotoxic; Ganciclovir and Valganciclovir (Valcyte) causes myelosuppresion, GI symptoms, as well as neurological symptoms; and Valacyclovir and famciclovir lack broad spectrum anti-viral efficacy. Many persons taking Valcyte report horrendous side effects, comparable to AZT. Typically, Valcyte costs $800 a month, and Isentress costs $950 a month. Raltegravir on the other hand has a very favorable side effect profile - when taken alone, it does not cause fat redistribution or raised cholesterol like other classes of HIV medications. It is rather unfortunate that very little research has been devoted to developing new classes of antiherpesvirals with better side effect profiles, since there is evidence that XMRV proliferates in EBV transformed B cells. It is also of note that B cell depletion through Rituximab provides a substantial improvement in CFS patients that lasts 3-4 months, but then returns, which leads to the conclusion that Lymphoblasts may very likely be where the secrets of CFS lie - unfortunately I do not know of any significant ongoing studies that have been conducted using bone marrow aspirations on CFS patients.