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Prototype blood test for vCJD

Fergus Walsh | 14:34 UK time, Thursday, 3 February 2011

Variant Creutzfeldt-Jakob disease is a terrible legacy of the BSE outbreak. The fatal degenerative brain disorder is the human form of Bovine Spongiform Encephalopathy, commonly referred to as "mad-cow disease". It first emerged in 1995. The disease, which affects the brain, is believed to have passed from cattle to humans through consumption of meat products contaminated with BSE.

The issue gets little publicity these days, but news in The Lancet medical journal of a prototype blood test for the condition is a significant moment. Researchers at the Medical Research Council Prion Unit at University College London have managed to devise a test which can spot the infectious proteins - prions - responsible.

The blood test was able to detect blood laced with a solution of vCJD to within one part per ten billion. It was around 70% accurate, so clearly there is work still to do, but the scientists are confident that accuracy will improve rapidly in the near future.

An accurate blood test would have far-reaching implications. Firstly, it would speed up diagnosis. Patients with vCJD are usually diagnosed late, only when they have begun to display symptoms. A sample of tonsils can usually tell doctors if they infected, but for a definitive diagnosis, a biopsy of brain tissue is required. So a blood test would mean simple and rapid diagnosis.

It would also provide the first accurate assessment of the extent of vCJD in Britain. This is a disease which began in Britain and most of those affected are here: out of 220 cases worldwide, 174 are British. Four of the British patients are still alive. Cases outside Britain are likely to be a significant underestimate, because doctors elsewhere often don't actively look for the condition.

Prions, which cause vCJD and other fatal diseases, can inhabit a person's body for 50 years before presenting symptoms. So there has always been a suspicion that the true scale of the vCJD infection has remained hidden. A study of tonsil samples suggested that 1 in 4,000 Britons might have the disease, but no-one really knows whether that is an accurate estimate (opens pdf). One positive fact is that the number of deaths from vCJD has been falling steadily since a peak of 28 in 2000.

An accurate blood test would also have implications for the National Blood Service. Currently, white blood cells are removed from donations and plasma products are imported. Blood donations are screened for HIV and Hepatitis B and C. If detected, donors are advised to speak to their doctor. But what if you were found to be infected with vCJD? If the test was not 100% accurate then it would raise the issue of so-called false-positive results. A commentary on the Lancet article says: "Communication to the public of the uncertainty around a positive test result will be challenging and could result in fewer donors as well as causing unnecessary anxiety to deferred uninfected donors."

The knowledge that you are harbouring vCJD, would be an extremely difficult issue to address. Some of those identified might never go on to develop to condition, so would have to confront an issue they would otherwise never have to face.

Variant CJD is a fatal condition for which there no proven treatment - although a number of experimental therapies have been tried. But there is scope for optimism here as well. Professor John Collinge, Director of the MRC Prion Unit was interviewed on Today on Radio 4 (listen again here). He said his team has been able to create human antibodies to the prion protein which blocked the disease in mice. Human clinical trials will begin in due course. Professor Collinge said: "There is an opportunity if we find people who are incubating the disease, in principle, to rescue them before they develop the disease itself."

That really would be a remarkable achievement.

Comments

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  • 1. At 3:47pm on 03 Feb 2011, pandatank wrote:

    There is a significant body of research pointing towards a different mechanism for vCJD. Prions exist in the body anyway. Research suggests that upsetting the Copper/Manganese balance within naturally occurring prions is what starts these prions creating such problems within the brain and CNS. The reindeer equivalent of CJD occurs in geographic hot spots where the common factor is the existence of manganese mine tailings. There are many commercial reasons why it is preferable for this research to remain in obscurity. Compensation for the "anti British Beef" campaign is just one. The other is the widespread use of chemicals known to have a significant effect in altering this balance, organophosphates being one category.

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  • 2. At 4:02pm on 03 Feb 2011, angelscomeinthrees wrote:

    Pandatank, I heard something years ago about deer getting a variant of CJD and organophosphates being the likely culprit.

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  • 3. At 5:51pm on 03 Feb 2011, concerned attorney wrote:

    It would be excellent news indeed if an early diagnostic test was found for CJD generally. However it appears that the latest news from Professor Collinge relating to a blood test for vCJD is just hype against the latest developments in Japan (as reported on 31st January 2011). Microbiologist Ryuichiro Atarashi and his team of Nagasaki University have developed an assay test known as real time quaking-induced conversion (RT QUIC) which correctly disgnoses CJD more than 83% of the time. If that is right it is more accurate than the alleged blood test developed by Professor Collinge. Furthermore Professor Collinge only seems to refer to diagnosing vCJD which represents less than 15% of all CJD cases. Surely an early diagnostic test is essential for all CJD and not just vCJD. But perhaps Professor Collinge is concentrating on vCJD (which is the minority) because there is a compensation scheme in place for the vCJD victims but not sCJD (which is the majority) or indeed for genetic or iotragenic CJD.
    Whilst an early diagnostic test is without doubt very desirable what about a treatment or a cure for CJD. The only currently available treatment (although not a cure) is Pentosan Polysulphate (PPS). Professor Collinge and his team at Queen Square refuse to administer PPS on CJD patients even though there are vCJD patients survising as long as 9 and 8 years on this treatment. There is also a sCJD patient surviving for almost 3 years on PPS. What news from Professor Collinge about a treatment and why does Professor Collinge refuse to administer the only treatment currently available?

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  • 4. At 11:58am on 06 Feb 2011, Graham Steel wrote:

    I completely agree with all the points mentioned by concerned attorney.

    Moreover, as mentioned in the Lancet Manuscript under discussion, there is a distinct COI issue in relation to two of the authors of it:-

    "Conflicts of interest
    JC is a director and JC and GSJ are shareholders and consultants for
    D-Gen (London, UK), an academic spinout company working in the fi eld
    of prion disease diagnosis, decontamination, and therapeutics. D-Gen
    markets the antibody used in this study. All other authors declare that
    they have no confl icts of interest".

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  • 5. At 1:03pm on 09 Feb 2011, SAH wrote:

    The progress of British scientists in developing an accurate test for vCJD must be applauded. It has the potential to enable early diagnosis of this insidious disease. It may also represent a first step towards developing a screening test for blood donors or for testing people considered at risk for public health purposes. The latter test, however, requires a great deal of additional work and could be several years away from completion.

    What seems to be lost in the euphoria is the excellent work that has been done by other British scientists at ProMetic Biosciences Ltd in Cambridge, working in collaboration with French and American counterparts, in developing a filter that significantly reduces the risk of transmission of vCJD through blood transfusion.

    As reported by the BBC, in late 2009, the Advisory Committee on the Safety of Blood, TIssue and Organs "SaBTO", recommended the adoption of a prion reduction filter to pre-treat red blood cells destined for children born since 1 January 1996. Studies evaluating the safety of filtered red cells have just been successfully completed using the P-CaptĀ® filter which has been CE marked and commercially available since 2006.

    It is laudable that British scientists have made progress on different fronts to address an intractable British public health issue. I would hope that the BBC would join me in encouraging the government to act now to adopt the P-Capt filter for all age groups while supporting future work to develop a screening test for vCJD. This two pronged approach will help improve blood safety and minimise the risk of vCJD transmission through blood transfusion for everyone.

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  • 6. At 12:36pm on 14 Feb 2011, sensiblegrannie wrote:

    pandatank' at post 1
    I wonder if what you are saying is nearer to the truth than the more popularized explanations given?

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  • 7. At 4:12pm on 25 Feb 2011, diamond281 wrote:

    I know that the test is a good few years away yet but I'm glad that a test is being researched on. You say that having the knowledge that you have it would be a burden for people. However, I know that for some people it will be a relief to know either way, like people who were infected with blood products in the 1980s, who recieved HIV and Hepatitis C. A lot of them have recieved letters stating that they could be at risk of vCJD. I know this because my Mum was one of those people. I think it would be relief for her and the whole family to find out if she has it or not since its an issue that is always on our minds already!

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