AM - Saturday, 3 November , 2007 08:12:00
Reporter: Jane Cowan
ELIZABETH JACKSON: If you get cold sores, that tingling feeling on your lip that signals the start of an outbreak is something you probably dread.
But now there is something else to be concerned about.
British researchers believe they've found evidence of a strong link between the herpes simplex virus and Alzheimer's disease.
Jane Cowan spoke to the leading researcher, Professor Ruth Itzhaki, from Manchester University.
PROFESSOR RUTH ITZHAKI: We found some years ago that the virus, this particular virus, is present in a high proportion of brains of elderly people, and we later found that in association with a certain genetic factor, the two together confer a strong risk of Alzheimer's disease.
And then more recently, we have been looking to see what effects the virus causes when it actually infects cells, and what we found was that it causes a large increase in the amount of a protein which is a major component of the plaque seen in Alzheimer brain, so all of these together really strongly suggest it is a cause; I don't say 'the' cause, I think the disease is multifactorial, but I think it's a cause, and probably a major one.
JANE COWAN: What could be the mechanism that is actually linking the herpes simplex virus to Alzheimer's?
PROFESSOR RUTH ITZHAKI: Well I think it affects what the virus does when it is in a cell, is to make everything in the cell - viruses live in cells, they can't live independently - and what it does to the cell is make the cell do what it wants, in other words, it causes the synthesis of parts of the cell which are useful for the virus to replicate itself, to form other viruses, and we don't quite know why.
We can explain part of the story, but not all of it.
JANE COWAN: If the cause of Alzheimer's is multifactorial, how much of an important factor do you think the cold sore virus might be?
PROFESSOR RUTH ITZHAKI: I think it could account for at least half of the cases, so it is really quite important.
JANE COWAN: If there is a causal link between cold sores and Alzheimer's, what's the potential for finding a vaccine for the cold sore virus that might also protect against Alzheimer's?
PROFESSOR RUTH ITZHAKI: Yes, well that's a good point. I think it's somewhere a long time in the future, at the moment there is no vaccine, and it would probably need to be given, if one were made, it would need to be given at quite a young age, because nearly everybody is infected with this virus sooner or later, and the point really, one of the points about it, is that once you get it, itstays in your body for life.
We are seeing that in older age we think it gets to the brain, in many cases. But a vaccine in feasible, in theory, but I think it will be quite a long way ahead.
ELIZABETH JACKSON: Professor Ruth Itzhaki from Manchester University, speaking to Jane Cowan.