MLV related viruses - a simpler explanation

MLV related viruses - a simpler explanation

For a more in-depth discussion of MLV-related viruses, please see my previous blog entry, here: MLV-related viruses - an explanation

MLV = Mouse Leukaemia virus

MLV's are mouse retroviruses that cause cancer in certain mice.

Judy Mikovits and Harvey Alter have discovered a variety of MLV-related viruses in ME/CFS patients.

These MLV-related viruses are not MLV's (mouse viruses) but they are closely related to them.

The only difference between Alter's viruses and Mikovits' viruses are that they are related to slightly different types of MLV's.

Judy Mikovits' viruses are related to Xenotropic MLV's, and so they are 'Xenotropic MLV-related viruses'.

Whereas Alter's viruses are related to Polytropic MLV's and so they are 'Polytropic MLV-related viruses'.

So the only difference between them is the use of the terms 'Xenotropic' and 'Polytropic'.

The terms 'Xenotropic' and 'Polytropic' indicate a slightly different behaviour of a virus.

XMRV = 'Xenotropic MLV-related virus':
X = Xenotropic
M = MLV (Murine Leukaemia Virus)
R = Related
V = Virus

Alter's viruses are 'Polytropic MLV-related viruses', and so he could have named them 'PMRV' (instead of XMRV). He hasn't named them PMRV, yet. Instead, he refers to them as Polytropic MLV-related viruses, or just MLV-related viruses.

All of the viruses found so far in the two papers, are MLV-related viruses, and they are Human Gamma Retroviruses (HGRV's), which is an umbrella term.

'Xenotropic' means that a virus cannot infect, or exist as a complete, replicating virus in its original host species (i.e. mice), but it can jump to another species (i.e. humans) where it can become a whole, complete, replicating virus.

'Polytropic' means that a virus can infect both its original host species (i.e. mice) and it can jump to another species (i.e. humans).

The difference in the meaning of the two terms is why the new viruses that Alter has detected cannot be called XMRV. Alter's viruses are related to Polytropic MLV's, not Xenotropic MLV's.

It remains to be seen how all of these new viruses, or variants, will be labelled and categorised.
XMRV's (more than one variant of XMRV has now been detected by Judy Mikovits) are clearly a subset of a larger group of viruses (MLV-related viruses and Human Gamma Retroviruses).
We might end up with a new collective name for all of these MLV-related viruses.

[UPDATE: It was reported, from the 1st International XMRV Conference, that Judy Mikovits suggested the name Human-MLV-Related-Virus (HMRV) to encompass Xenotropic and Polytropic MLV-Related Viruses.]

Are Alter's viruses and Mikovits' viruses different variants of the same virus, or are they totally different viruses?
Obviously there are differences, but the similarities seem to be more significant than the differences.

Alter says that these differences are exactly what he expects to see in a retrovirus, so these observed virus mutations support the type of human retrovirus infection that Mikovits' XMRV research indicated.
Alter says that the Hep C and HIV viruses exhibit the same pattern of variants as this new type of human retrovirus that Alter and Mikovits have found in ME/CFS patients.

Indications from Alter are that all these viruses might be referred to as variants of a single disease associated virus, just the same as the multiple Hep C virus variants are often referred to as the Hep C virus (singular).

Of course, it might turn out that these retroviruses are also associated with other diseases, such as Fibromyalgia, Gulf War Syndrome, MS and Autism.

It has recently been reported that Judy Mikovits has also now found polytropic MLV-related viruses in some of the samples from her original Science study. This means that Mikovits is finding more than one virus type in individual patient samples.

But in the months since then, they have continued to study the CFS patients included in the Science paper and Mikovits says that almost all of them are positive for one or more MLV-related viruses, including X and P.

See here for a diagram, extracted from the Alter & Lo paper, of a 'phylogenetic tree' (i.e. a virus family tree) of MLV-related viruses... Specifically, the diagram shows the relationship of viral gag gene sequences, taken from blood samples of CFS patients and blood donors in Alter's paper, with other MLV's:

One other interesting thing to note is that the 'commentary' in PNAS says that:
...XMRV genomes are actually hybrids between polytropic endogenous MLV sequences ... and xenotropic MLV ...
So I believe that whether these new viruses are related to either polytropic, or xenotropic MLV's, is not clear-cut and is not particularly significant... It's just a case of wording, and possibly an unfortunate case of using an 'X' in the naming of XMRV.



Has there been any research or theory into how this family of viruses produces the symptoms we see? Thanks very much for your work.
And more importantly, what treatment is beneficial? It's a virus....great. Many of us knew that...what next?
Hi Christopher, I have read (sorry, can't remember where) that Judy Mikotits has now done some research that links XMRV with immune system abnormalities. I think she said that the work will be published towards the end of the year, before Christmas. This is a significant piece of research because it is the first time that XMRV has been shown to be linked to the symptoms that we experience. I'm sorry that I don't know any more details.
Hi The Spitfire, I believe that there are a number of research projects being set up to start to investigate the possibility of treating ME/CFS (XMRV positive) patients with anti-retrovirals. Also, there has been some reported success in treating a subset of ME/CFS patients with other anti-virals (not anti-retrovirals). Dr Lerner, and others have been looking into these anti-viral treatments. Unfortunately you have to seek out specialist clinicians to receive this sort of treatment, or do a good job of persuading your own doctor if you live in the USA (no hope of doing this in the UK on the NHS). The XMRV research is at such an early stage, that it's going to take a bit of time for all of these studies to get going. Some individual ME/CFS patients have been blogging about their own experiences of taking anti-retrovirals, and at least one blogger (there maybe more, but I haven't been following these stories closely) has reported experiencing considerable improvements
Thanks Bob,

I will have to check this out. I know that valcyte just about killed some of my friends livers. It was such a rough treatment. I have it and I am scared to try it.
Hi The Spitfire,
I don't know anything about anti-retrovirals, but I would suggest that, if you were thinking about taking them, then you see a clinician...
As you say, anti-retrovirals can be dangerous.
Also, you would need to know which drugs were effective for XMRV (not all of them are), and what doses to take.
And I don't know if your blood would need to be constantly monitored for toxins and damage to the liver etc.
I would suggest doing some solid research before even seeing a clinician about it as well... because, unless you see an ME specialist, then they probably won't have even heard of XMRV.

Here's some extra info:

Here's an interesting blog entry by m0joey about antiretrovirals, other antivirals, clinicians and proposed research projects:

And here's some news about possible trials:

"Judy A. Mikovits, the senior author of the Science paper, said she hoped to organize clinical trials of anti-retrovirals by the end of the year, noting that they could lead to answers about whether a retrovirus causes the disease as well as to effective treatments. (Mikovits is director of research at the Whittemore Peterson Institute for Neuro-Immune Disease at the University of Nevada, Reno, which collaborated on the XMRV study with the National Cancer Institute and the Cleveland Clinic.)

Cara Miller, a spokeswoman for Gilead, which makes one of the HIV drugs tested against XMRV, said the company was interested but proceeding cautiously".

And here's an interesting discussion post by George:
Hi CFScandy...
Sorry to hear about your health problems... it sounds like you've been through a lot of pain and heartache...
I'm afraid that I'm not qualified to answer your questions...
If ME/CFS turns out to be caused by a retrovirus, then yes, I think we can assume that it would be infectious.
But also, there are triggers for ME/CFS which can involved other pathogens and toxins.
I got ill while working in a hospital, so I imagine that i was exposed to a trigger pathogen, or it was related to the three Hep B vaccine boosters that I received.
It seems that not everyone who carries XMRV, or a similar virus, has ME, so I guess it might be possible that your husband is an XMRV carrier... but the research is in such early stages yet, we really don't know much about it.

Some of the well known US physicians have ME patients who have had rare forms of cancer, but I don't know the details about this... I believe that the WPI have been studying some of these patients.
Also, Autism has been linked to the MMR vaccines, which included mumps, and there is research going on for a link between Autism and XMRV... so there might be a (tenuous?) link there between your early episode of mumps, and what you are experiencing now... But this is just guess work on my part. I don't know if mumps has ever been linked to ME/CFS or other neuro-immune diseases.

Sorry i can't be more help,
Best wishes,
Bob, this is the first good explanation i read about the PNAS paper and i really appreciate the clear and simple way you laid it out!

I would suggest to Cort to make this blog a head line article as a summary of the PNAS paper , which should replace all the other confusing and misleading articles
Hi aruschima, thanks for the positive feedback... very kind of you... I'm glad that it helped you... yes, feel free to post it on another board... maybe you could include a link (to this blog page).

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