Monday, August 2, 2010


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This past spring, Dr. Ila Singh at the University of Utah conducted one of three recent studies testing HIV antiretrovirals against XMRV in vitro (in the test tube).  Singh discovered that two drugs—tenofovir and raltegravir—killed the XMRV retrovirus, and corroborated an earlier study by the Mayo Clinic that concluded that AZT is also effective against XMRV.  In addition, Singh found any two combinations of these three drugs were synergistic.  She didn’t test all three drugs together, so it’s not known if a triple cocktail would be even more effective.  It’s also possible that the triple cocktail could be less effective than a two-drug combo.

Likewise, a June 2010 study by the National Cancer Institute also found that AZT, tenofovir and raltegravir inhibit XMRV in vitro.  Here’s a capsule view of the three drugs:

Nucleoside Analogue Reverse Transcriptase Inhibitors
Zidovudine (brand name AZT).  FDA-approved in 1987, AZT was the first drug used to treat HIV/AIDS, though it was developed in the 1960s as a cancer drug.  In 1974, German scientist Max Planck discovered that AZT was active against a mouse retrovirus called Friend murine leukemia virus, a close cousin of XMRV.  In HIV, AZT works by stopping the enzyme reverse transcriptase from converting the retrovirus’s RNA into DNA, which is then integrated into the genetic material of the host’s cells. Normally DNA transcribes (converts) RNA.  Reverse transcription is the reverse: RNA transcribes DNA.  Nucleoside analogue reserve transcriptase inhibitors are often abbreviated NRTIs.

Common side effects of AZT include:  nausea, loss of appetite, headache, tiredness, vomiting, constipation, asthenia (weakness).  Less common side effects:  anemia, bone-marrow suppression, bruising, muscle pain and myopathy (muscle weakness), mitochondrial toxicity and lactic acidosis, body-fat redistribution, elevated liver enzymes and liver damage, a bluish discoloration of fingernails and toenails, and allergic reactions.  Nausea is the most common side effect from AZT and can be minimized by taking the drug with food.  However, high-fat meals tend to exacerbate the nausea.

Nucleotide Analogue Reverse Transcriptase Inhibitors
Tenofovir (brand name Viread).  Nucleoside analogs are converted into nucleotide analogs by the body. If you take nucleotide analog reverse transcriptase inhibitors (often abbreviated NtRTIs), you bypass that step.  FDA-approved in 2008, Tenofovir, like AZT, blocks the retroviral attack on the host’s healthy cells by preventing the reverse transcriptase enzyme from doing its job of transcribing single-stranded viral RNA into double-stranded viral DNA.

Common side effects of tenofovir include: diarrhea, headache, pain, depression, rash, asthenia (weakness), nausea.  Less common side effects:  vomiting, gas, loss of appetite, weight loss, insomnia, dizziness, sweating, muscle pain and myopathy (muscle weakness), mitochondrial toxicity and lactic acidosis, kidney and liver damage, Fanconi syndrome, exacerbation of hepatitis, decrease in bone density, elevated blood sugar, fast or irregular heartbeat, and allergic reactions.  Kidney toxicity can occur within the first few months of taking Tenofovir, so kidney function must be monitored.  Dehydration contributes to kidney toxicity and can be minimized by drinking more water.

Integrase Inhibitors
Raltegravir (brand name Isentress):  FDA-Approval in 2007, it’s the first and only approved integrase inhibitor, though others are in the pipeline.  Integrase inhibitors block a later phase of retroviral integration than NtRTIs or NRTIs do.  Raltegravir prevents the enzyme called integrase from inserting double-stranded viral DNA into the host cells’ DNA. 

Common side effects of raltegravir include: rash, headache, nausea, asthenia (weakness) and fatigue.  Less common side effects:  gastritis, abdominal pain, insomnia, dizziness, fever, anemia, diarrhea, insomnia, rash, kidney damage, kidney failure, high blood sugar, depression, and allergic reactions.

With HIV patients, one drug is started and a second drug in added one to two weeks later, and a third drug is added one to two weeks after that. 

Dr. Ila Singh discussing XMRV and the HIV drugs being tested in animals inoculated with XMRV:

Video Courtesy of

This post should not be construed as medical advice.  Nor is this post an endorsement of the use of antiretrovirals for ME/CFS patients and an XMRV diagnosis.  I am a science writer, not a physician or a researcher.  Consult your health-care professional before beginning any treatment plan.

Coming up:  Drugs that may help clear XMRV reservoirs.  Plus an interview with the CDC's Dr. Steve Monroe, director of the CDC’s division of High Consequence Pathogens and Pathology.

This article is copyright CFS Central 2010.  All Rights Reserved. You may quote up to 150 words from this article as long as you indicate in the body of your post (as opposed to a footnote or an endnote) that the excerpt is by Mindy Kitei for CFS Central.  You may not reprint more than 150 words from this article on blogs, forums, websites or any other online or print venue.  Instead, refer readers to this blog to read the article.


  1. On April 1, 2010, Dr. Singh did an interview with a local Utah television station (, discussing the results of her PLoS One article on Raltegravir:

    In the TV interview, Dr. Singh discusses studies already underway with Colorado State Univ. designed to assess the effectiveness of ARV therapy targeting XMRV in lab animals.

  2. Thanks, CBS. I just embedded the Dr. Singh interview in the post.

  3. It's great to have you Mindy. Your articles makes the waiting for progress a little less unbearable. The lack of news can be mindnumbing sometimes. THANK YOU!

  4. Thank you for another excellent article. It is so good to have the information on these three drugs condensed in one place.
    --Patricia Carter

  5. Thanks, Mindy. People keep talking about the nasty side-effects of antiretrovirals, but aside from the potential for kidney and/or liver damage, the side-effects sound pretty much like what ME/CFS patients live with everyday anyway. I wonder if the people warning about how bad the side-effects are to live with have any idea what living with ME/CFS is like.

    Interesting clip of Dr Singh. And a good reminder of how much needs to happen before those drugs are ready for XMRV patients (assuming the evidence ends up showing that XMRV causes disease). We've got a long wait ahead of us.

  6. I agree,I am an FM patient and acknowledge that these symptoms are indeed what we live with daily,My concern though,Would taking these meds not exacerbate the the already nasty symptoms of FM.

  7. Would one need to take these drugs indefinitely?

    I have a mild case of CFS, so from where I stand, the side effects look pretty bad. If I could take it for a while and kill the retrovirus, it would be worth it. If I had to take it forever, not a good deal for me.

  8. unfortunately, you would have to take the drugs forever...unless they come up with a way to eradicate retrovirus from all latent cells, which is a long way off i think.

    mindy....great article. i hadn't heard about research to get at the XMRV reservoirs yet! is this brand new info?

    thank you


  9. Anonymous, The reservoir stuff is theoretical at present, but interesting. There's been some exploration to clearing the HIV reservoirs, but actual therapies are still years away. If you could completely clear the retroviral reservoirs, theoretically you could conceivably be cured of HIV, discontinue therapy and remain healthy.

  10. This info may seem off the wall to many of you but here goes: I have fibromyalgia/CFS. A 50 year old cousin was originally rx'd with Parkinsons but two years later told he has Lyme. He landscapes wild animal parks, zoos, etc. Lyme makes a lot of sense. I researched and researched and discovered If you Google Carnivora HIV you will see studies whereby it successfully treated HIV. Same with Lyme. Carnivora is based on the Venus Fly Trap plant. After three months my cousin is feeling well enough to go back to work. After this info re MFRV reached me I put myself on Carnivora. Too soon to tell but I am hopeful. Think it sure beats HIV cocktails. Personal opinion of course.
    Barbara Lochner

  11. This is very great thing you have shared with us. Now I found enough resources by your tips about this issue, Thank you.


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