No Evidence of Murine Leukemia Virus-Related Viruses in Live Attenuated Human Vaccines

6 Jan

There has been much discussion of XMRV, Xenotropic murine leukemia virus-related virus, here at Left Brain/Right Brain and elsewhere in the past few months. The reason for the discussion here is the (now shown to be false) idea that XMRV is implicated in autism causation. Two papers have addressed this question and found no evidence of a link. XMRV came to prominence as a possible candidate in causing chronic fatigue syndrome (CFS). Multiple papers have found no evidence of a link between XMRV and CFS (fan example is discussed here) and the original paper on the topic was withdrawn by editors of the journal Science after it became clear that those results were suspect.

The idea that autism and XMRV was promoted by David Kirby, whose efforts also strongly promoted the debunked autism-epidemic-caused-by-mercury idea. Mr. Kirby’s article at the Huffington Post was Is Autism Associated with A Viral Infection?. In this he quoted CFS/XMRV researcher Judy Mikovits:

And then Dr. Mikovits dropped a bombshell that is sure to spark controversy.

“On that note, if I might speculate a little bit,” she said, “This might even explain why vaccines would lead to autism in some children, because these viruses live and divide and grow in lymphocytes — the immune response cells, the B and the T cells. So when you give a vaccine, you send your B and T cells in your immune system into overdrive. That’s its job. Well, if you are harboring one virus, and you replicate it a whole bunch, you’ve now broken the balance between the immune response and the virus. So you have had the underlying virus, and then amplified it with that vaccine, and then set off the disease, such that your immune system could no longer control other infections, and created an immune deficiency.”

Mr. Kirby went on to write:

So there you have it – a possible explanation of regressive autism in a significant number of cases associated with immune system deregulation triggered by vaccination.

Of course, much more work is needed to nail down the exact significance of such an association. For example, is the virus implicated in the cause of autism, or do children harbor the virus as a result of autism?

Yes, Ms. Mikovits and David Kirby were proposing a possible link between autism, XMRV and (of course) vaccines.

That was October 2009. Fast forward to today, two years later and we see

A) Neither Ms. Mikovits nor anyone else has published the data supposedly linking XMRV and autism

B) Two studies have looked for evidence (and failed to find any) of a link between XMRV and autism,

Lack of infection with XMRV or other MLV-related viruses in blood, post-mortem brains and paternal gametes of autistic individuals.

PCR and serology find no association between xenotropic murine leukemia virus-related virus (XMRV) and autism.

C) Evidence has arisen that much of the data linking XMRV to CFS is faulty.

Studies on XMRV are still ongoing. If experience from the vaccine-autism-epidemic idea tell us anything, the idea that XMRV causes CFS and/or autism will die slowly and even more data are needed.

To that end, a recent study explored whether XMRV is a contaminant in live virus vaccines. (note that in other vaccines, the XMRV is likely as dead as the other constituents of the vaccine). You can tell the result from the title: No Evidence of Murine Leukemia Virus-Related Viruses in Live Attenuated Human Vaccines.


The association of xenotropic murine leukemia virus (MLV)-related virus (XMRV) in prostate cancer and chronic fatigue syndrome reported in previous studies remains controversial as these results have been questioned by recent data. Nonetheless, concerns have been raised regarding contamination of human vaccines as a possible source of introduction of XMRV and MLV into human populations. To address this possibility, we tested eight live attenuated human vaccines using generic PCR for XMRV and MLV sequences. Viral metagenomics using deep sequencing was also done to identify the possibility of other adventitious agents.


All eight live attenuated vaccines, including Japanese encephalitis virus (JEV) (SA-14-14-2), varicella (Varivax), measles, mumps, and rubella (MMR-II), measles (Attenuvax), rubella (Meruvax-II), rotavirus (Rotateq and Rotarix), and yellow fever virus were negative for XMRV and highly related MLV sequences. However, residual hamster DNA, but not RNA, containing novel endogenous gammaretrovirus sequences was detected in the JEV vaccine using PCR. Metagenomics analysis did not detect any adventitious viral sequences of public health concern. Intracisternal A particle sequences closest to those present in Syrian hamsters and not mice were also detected in the JEV SA-14-14-2 vaccine. Combined, these results are consistent with the production of the JEV vaccine in Syrian hamster cells.


We found no evidence of XMRV and MLV in eight live attenuated human vaccines further supporting the safety of these vaccines. Our findings suggest that vaccines are an unlikely source of XMRV and MLV exposure in humans and are consistent with the mounting evidence on the absence of these viruses in humans.

Yes, there is no evidence of XMRV in vaccines. This is rather anticlimactic given the evidence already in place that XMRV is not linked to autism, and the fact that the XMRV/CFS link is already tenuous at best.

The blogger erv has done the most thorough job following the XMRV study out there, including discussing the paper above. Others have taken up where David Kirby left off and promoted the idea that XMRV and autism are linked, and that vaccines are a possible part of that link. I would hope that those people would see the value in letting their readers know about this paper (and others, and the retractions).

9 Responses to “No Evidence of Murine Leukemia Virus-Related Viruses in Live Attenuated Human Vaccines”

  1. Neuroskeptic January 6, 2012 at 11:02 #

    So a virus that doesn’t do anything, is not present in vaccines, which don’t cause autism.

    Check mate.

  2. Jack January 6, 2012 at 11:43 #

    Great to see you covering this paper. I would like to think that Kirby will also cover this – he must have some idea of how hopes can be so easily and wrongly raised by mere speculation. He is therefore morally obliged at least to cover the retractions and this lack of association with vaccines. He knows the score.

  3. _Arthur January 6, 2012 at 14:34 #

    A throwaway hypothesis takes just minutes to be uttered on the web, and take years and hundred of thousands of dollars of research grants to scientifically disprove.

    Like, say, the throwaway hypothesis that “autistic children are bad mercury excretors”.

    And no matter how soundly the -throwaway- hypothesis has been disproven, it will be used again and again and again by the denialists. They don’t need research, they just need to feed their own inner certainties.

  4. Chris January 6, 2012 at 18:31 #


    He is therefore morally obliged at least to cover the retractions and this lack of association with vaccines. He knows the score.

    If Kirby was moral he would have withdrawn is book Evidence of Harm. Especially after he predicted autism would decrease four years after thimerosal was removed from pediatric vaccines in 2002.

  5. Prometheus January 6, 2012 at 20:17 #

    As has been noted above, this study shows that a virus – XMRV – that hasn’t been shown to cause disease in humans isn’t present in vaccines.

    So, an off-the-cuff comment by a researcher results in the need to spend thousands of dollars and who knows how much research time to show that something that isn’t a problem in humans also isn’t present in vaccines.

    The terrible reality is that this study – no matter how good it is – will have absolutely no effect on those people who are now “convinced” that XMRV in vaccines causes autism, because they also believe that anyone who contradicts their beliefs – even if the have real data – is conspiring to hide the “True Cause of Autism”.

    What a mess!


  6. bullybeef January 6, 2012 at 21:23 #

    The specifics of the “XMRV” is pretty complicated.

    You see “XMRV” means a number of different things simply because it was mis-termed in the Mikovits/Lombardi paper. And Mikovits didn’t wish to specifically use “XMRV” when the paper was published.

    “XMRV” was first coined as a new human retrovirus, the first since HIV, when it was discovered by Robert Silverman of the Cleveland Clinic when it was found in prostate cancer cells in 2006:

    The reason for this discovery was due to a RNASE-L enzyme deficiency in people with a particular prostate cancer.

    Mikovits discovered this same deficiency in people with ME, and that led to her finding a human gamma retrovirus within her ME patients. I am unaware whether this deficiency exists in children with autism, but it is worth looking up.

    The issue then was Mikovits isolated her virus, whilst Silverman only cloned his discovery; he made 3 clones, one of which was termed VP62/XMRV. Mikovits at first thought her “XMRV” was the same as what Silverman discovered.

    Then every study that has since looked to replicate the Mikovits paper used VP62 as their positive control. They actually looked for a new virus using a clone that doesn’t exist in nature – it was man-made. They didn’t use the isolate that Mikovits found. So they didn’t even attempt to replicate.

    It was later admitted by Silverman that VP62/XMRV was a man made contamination, and not the same as he found in the prostate cells.

    And it also wasn’t the same as what Mikovits found in her patients. The problem has remained though that every denialist that researched the human gamma retrovirus(HGRV)link in ME insists that VP62 was the same thing Mikovits discovered. Yet there is no proof of that accusation whatsoever.

    Because Mikovits isolated her sample, it couldn’t be the same because Silverman’s VP62/XMRV was a man made artefact from his lab only.

    So basically nomenclature and confusion has been used to stall the science involved in accepting this new discovery publicly.

    There are many possible reasons to stall this discovery, and one that stands out is whether vaccines have been contaminated with HGRV throughout history. HGRVs are Murine-like Leukaemia viruses, and they mutated from wild mice, were they are called MuLV. Obviously health officials would be very nervous if this was the case.

    Another reason is prevalence. Early studies have estimated the infectious rates of HGRVs at around 7% of the healthy population that could be unknowing carriers. That would equate to 1 in 14 healthy people carrying an new retrovirus of unknown pathogen. Or half a billion people globally.

    So, if HIV is an epidemic with around 35million people globally infected, what would 500,000,000 HGRV infected people be? Scary. And that figure doesn’t even include the people whom have developed disease.

    When I first heard this news back in 2009, I did the maths and predicted that there would be more reasons for governments to put this genie back in the bottle, than to admit it.

    But obviously a conspiracy theory is only that until the facts are admitted by the governments themselves.

    So the retraction of recent “XMRV” papers isn’t a big surprise to me. But the story doesn’t end there.

    As we speak, Dr. Ian Lipkin of the National Institutes of Health is organising another federal study into “XMRV” and murine-like leukaemia viruses (MLV) in ME.

    He recent blogged about it on his his university’s website:

    Interesting, out of all the participants in that study, four scientists have located HGRVs in humans, and two haven’t, but they admitted in their papers that they used the VP62/XMRV as their positive clone.

    Obviously it will be interesting whether this study actually uses a true positive control to find HGRVs. For this reason much of the ME community remain pessimistic that this study will again be negative because they won’t use a natural HGRV positive control to locate the virus.

    All I can say is stay tuned.

    • Sullivan January 6, 2012 at 22:11 #


      you are probably unaware of how familiar your story is. Substitute “vaccines” or “mercury” or “persistent measles infection” for XMRV. Substitute autism for CFS/ME. Go back in time about 10 years.

      The hope that there is something in this, even though there is no evidence, is palpable. The idea that “Well, they are funding more research, so there must be something there” is a direct echo from the past, right down to Ian Lipkin being involved.

      Prof. Lipkin is not “organizing” another federal study. He is head of one he already organized. Prof. Lipkin was also the head of the team that tried to replicate Andrew Wakefield’s claims of measles virus in the guts of autistic children. Heck, he’s even teamed with Maddy Hornig (who was lead author on the autism paper).

      Sure, the idea isn’t dead. It isn’t very alive either.

      As you state, Prof. Lipkin has blogged about it. The final line: “Thus, irrespective of study outcome there will be unprecedented opportunity to explore hypotheses other than that disease is due to XMRV or MLV infection.”

      When I first heard this news back in 2009, I did the maths and predicted that there would be more reasons for governments to put this genie back in the bottle, than to admit it.

      But obviously a conspiracy theory is only that until the facts are admitted by the governments themselves.

      Change 2009 to 1999 and you are channeling a number of the autism “advocates” of old.

      I hope should the Lipkin study go against your views you have the courage to change your mind. Those who have rigidly adhered to the failed hypotheses in autism have done a great deal of damage.

  7. Prometheus January 7, 2012 at 21:49 #

    Bullybeef raises some interesting points, but the problem with all of them is that “HGRVs” (human gamma retroviruses) haven’t been shown to exist – not even one. XMRV was thought to be the first HGRV and now it looks as though all of the reports – perhaps even those in human prostatic cancer cells – are the result of contamination.

    As a result, all of the scary maths Bullybeef has done come to nought.

    Mikovits has been involved in enough questionable activity to call the results of her team into question, even if there hadn’t been a problem replicating her results. As of now, it is an open question whether XMRV or any gamma retrovirus can infect humans. Only further research will tell.

    Even if we assume – against the available data – that the XMRV findings from research groups other than the Mikovits group are real and not due to contamination, we are left with another “dog that didn’t bark” problem: if 7% of the general population is infected with XMRV, why aren’t we seeing an explosion of leukaemia?

    Of course, Bullybeef shows his/her colours near the end of the comment:

    “But obviously a conspiracy theory is only that until the facts are admitted by the governments themselves.”

    It’s hard to imagine that a “conspiracy” of the magnitude proposed by Bullybeef wouldn’t have already been exposed. It doesn’t take an admission by “the governments themselves”, just a GS-4 clerk who wants to be on the “Oprah” show. Massive conspiracies don’t work – there are too many people who can leak information.

    Nice try, though. Bullybeef might try selling the idea to John Grisham or Dan Brown, but it might be too far-fetched for even them.


  8. Jack January 7, 2012 at 22:23 #

    You know having listened to the Nevada Newsmakers coverage linked to in Kirby’s article – he might have done better quoting the clarification that followed from Annette Whittemore – to the effect that ‘we are not saying that vaccines cause autism’.
    As for the rest of that broadcast – a very scary reminder of how it all began…
    n.b. to find it you have to search for mikovits as guest and download – 10/03/09 I think.

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