CJD: Research reveals weaker strains can protect
People could develop an immunity to variant Creutzfeldt-Jakob disease (vCJD) and similar conditions after persistent exposure to milder strains of the agent that causes them, researchers have suggested.
Scientists at Yale and Nagasaki University medical schools have found that regular doses of the weaker infection appeared to offer protection against the disease.
It is known that misfolded proteins, called prions, are present in brain and nerve tissue infected with vCJD, as well as related diseases known as 'transmissible spongiform encephalopathies (TSEs). Other TSEs include classic CJD, BSE, which infects cattle, and scrapie, which infects sheep. However, it is not known whether prions cause these diseases or are a result of them.
In the study, scientists looked at the effects of prion diseases on mouse brain cells. They found that cell cultures with a weak strain of CJD were protected from infection by two strains of sheep scrapie agent. In turn, one of these sheep strains also appeared to protect against a virulent form of CJD strain.
In addition, it was found that the presence of a weak CJD strain protected cells from infection by a more virulent and potentially lethal form. Researchers also found that the protection effect did not involve cells from the immune system.
Professor Laura Manuelidis of Yale University said: "This gives us a better idea of what to target, as the results are not consistent with the concept that abnormal forms of the prion protein are infectious."
