NR ASNJ
AU Wise,J.
TI Agents of new variant CJD and BSE are identical
QU British Medical Journal 1997 Saturday 4 October; 315(7112)
PT Letter
VT
Two independent studies have confirmed that the new variant form of Creutzfeldt-Jakob disease (nvCJD) is caused by the same prion strain as bovine spongiform encephalopathy (BSE) in cattle. This makes it highly likely that people who developed nvCJD contracted it by eating meat from cattle with BSE.
In one of the studies Moira Bruce and colleagues from the Institute of Animal Health in Edinburgh injected mice with infectious brain samples from cows, patients with nvCJD, patients with sporadic CJD, and farmers who died of CJD after working with animals with BSE (Nature 1997;389:498-501). They found that the histological presentation, symptoms, and course of nvCJD is identical to that of BSE in mice and distinct from other forms of CJD. They also confirmed that CJD occurring in farmers in recent years is the sporadic form and is not related to BSE.
In the other study Professor John Collinge and colleagues from the Prion Disease Group at the Imperial School of Medicine, London, used a biochemical assay to show that the BSE and nvCJD agents are the same and are distinct from other forms of CJD in humans (Nature 1997; 389:448-50). They used ordinary and transgenic mice - the latter genetically modified so that they were highly sensitive to typical CJD. The infectious agents produced in the mice brains infected with BSE agent and those infec-ted with nvCJD agent isolated from human brain tissue were indistinguishable, indicating that they are the same strain.
Professor Collinge said: "We believe that the combined weight of the epidemiological evidence, experimental transmission to primates published last year by the Paris group, our molecular strain typing work, and now these latest studies, leads to the same inescapable conclusion: new variant CJD is the human counterpart of BSE." Professor Collinge believes that the most likely explanation is exposure to bovine offal before it was banned.
Jeffrey Almond from Reading University and John Pattison from University College, London, comment that the two new studies provide "compelling" evidence that nvCJD is human BSE. There have been 21 confirmed instances of nvCJD in the United Kingdom, but the rate of new cases is not increasing, and so they say that there is hope that the overall number of cases will be relatively small. They say, however, that "much depends on the average incubation time of nvCJD: the longer the time the higher the final figure will be."
ZR 0
SP englisch