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Retroviruses and ME

Professor Greg Towers (London, UK) has studied the lifecycle of retroviruses and  spoke on the relationship between retroviruses and ME. He went through the reasons as to how and why XMRV is not a human pathogen, but a mouse gamma retrovirus.  He outlined the initial prostate study which had described XMRV as being present in prostate cancer. He outlined the basic steps of retroviral replication, and explained how endogenous retroviruses get into the genome. He showed how cells will grow if injected into mice but not in a laboratory dish. Excitement originally arose because if XMRV had been implicated in ME, it could lead to potential diagnosis and treatment. After the original XMRV discovery by the Mikovits lab, there were a series of negative studies, and the subsequent conclusion that XMRV was a laboratory contaminant. Towers had looked to see where the ancestral strains had arisen. The cell line had come from mice, and was then intermingled with the human line. They were not separate sources.

The Lipkin study provided the final closure using 150 patient samples and 150 controls, analysed blinded in different centres. There were no differences between samples and controls, and it was finally concluded that XMRV is not a human pathogen. It is a mouse virus generated around 1994 and not aetiologic of ME. Genetic evidence can be used to determine origin. It was also concluded that PCR is very sensitive and needs to manage inevitable contamination.

Towers emphasised that “This should not ever happen again” and new pathogens need more rigour.