Summary of MLV-related terminology and abbreviations

MLV = Murine Leukaemia Virus. MLV's are mouse retroviruses that cause cancer in certain mice.

MuLV - MLV's are also known as MuLV's.

mERV - Some types of MLV's are also known as mERV's (mouse endogenous retroviruses), but not all MLV's are endogenous.

XMRV is a human retrovirus and it is similar to (but not the same as) certain MLV's (mouse viruses). XMRV is not an MLV, but it is a human virus, known as an 'MLV-Related Virus' because of its similarities to certain MLV's. XMRV is an 'MLV-related virus' which was discovered in 2006 in prostate cancer patients.

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

MLV-Related Virus indicates that XMRV is similar to MLV's (mouse viruses), but it is genetically different enough (i.e. it has mutated) to be classified as human viruses. XMRV has never been found in mice, so far. Human 'MLV-Related Viruses' (e.g. XMRV, PMRV) have now been found in prostate cancer patients and in ME/CFS patients.

PMRV = 'Polytropic Murine Leukaemia Virus-Related Virus' ('PMRV' could be used as a possible informal abbreviation, but it doesn't seem to have been used much):
In the NIH/FDA paper, Alter and Lo discovered new viral gene sequences, similar to XMRV, but which they say are more similar to 'polytropic' MLV's than to xenotropic MLV's. This is why the new virus gene sequences can't be called 'XMRV'. These new gene sequences have been referred to as 'Polytropic-MLV-related viruses'. The prefixes 'Xenotropic' and 'Polytropic' are used describe the behaviour of the MLV viruses (see below for explanation.)

HMRV = 'Human MLV-Related Viruses' = Judy Mikovits unofficially uses this new name for both XMRV's and PMRV's (i.e. 'HMRV' would describe all the known MLV-Related Viruses). It seems that the distinction between P-type and X-type related viruses might not be particularly significant for the purposes of researching ME, and the differences are not clear-cut as the XMRV genome is a hybrid of both Xenotropic MLV's and Polytropic MLV genes sequences.

HGRV = Human Gammaretrovirus = A proposed umbrella term for all human gammaretroviruses. Gammaretroviruses are a category of retroviruses which include MLV's. XMRV and PMRV are the only known human gammaretroviruses. HIV is a 'lentivirus', not a gammaretrovirus.

Xenotropic (X-type) (XMRV = Xenotropic MLV-related virus):

Xenotropic = Cannot infect the cells of the original host species (i.e. mice) with complete, replicating viruses but can infect another species (i.e. humans) with complete and replicating viruses.

Polytropic (P-type) (PMRV = Polytropic MLV-related virus):

Polytropic viruses can infect both the cells of the original host species (i.e. mouse) and another species (i.e. humans) with complete and replicating viruses.

Extra Note:
Judy Mikovits has reportedly now found both Xenotropic and Polytropic MLV-Related Viruses in the ME patient samples from her original Science study. She sometimes refers to them, collectively, as 'HMRV'.


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