A Simpler Explaination

Just found this post at Phoenix Rising. It is a great explaination of the two studies that have just been published that found MLV viruses in 80% of CFS patients. For the entire article with comments and links to other papers click here.



MLV related viruses - a simpler explanation
by Bob
on August 30th, 2010 at 07:36 PM
11 Comments

I've already posted a blog about MLV-related viruses but I thought it might be quite difficult to follow for some people who can't follow the science easily... So I've now written this shortened, simpler, version, which hopefully might be easier to grasp. (feedback welcome.)


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 replicate 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.

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, Autism.