ACCESSION NO:  96-97-1641
       TITLE:  Deadly Enigma
      AUTHOR:  BEARDSLEY, TIM
     JOURNAL:  Scientific American
    CITATION:  December, 1996, 275: 16, 18.
        YEAR:  1996
    PUB TYPE:  Article
 IDENTIFIERS:  PROTEINS; MAD COW DISEASE; TRANSMISSIBLE SPONGIFORM 
               ENCEPHALOPATHIES; CREUTZFELDT-JAKOB DISEASE; PRION PROTEIN; 
               BRAIN DISEASES; DISEASE TRANSMISSION
    ABSTRACT:       An abnormal form of a protein present in all mammals 
               causes at least 15 different lethal brain diseases affecting 
               a wide variety of animals. Some mysterious agent that resists 
               standard chemical disinfection and high temperatures can 
               transmit these diseases--such as scrapie in sheep, mad cow 
               disease in cattle, and Creutzfeldt-Jakob disease in humans--
               between individuals and even between species. It is unknown 
               how the agent spreads under natural conditions and how it 
               destroys brain tissue. The diseases are called transmissible 
               spongiform encephalopathies (TSEs) because of the 
               characteristic spongelike appearance of brain tissue.
                    Mad cow disease has turned into a national crisis in 
               Great Britain, and there is fear that the disease, which 
               causes animals to become nervous and develop an unsteady 
               gait, will spread to people. British researchers have 
               identified 14 unusual cases of Creutzfeldt-Jakob disease in 
               young people they suspect were a human manifestation of mad 
               cow disease, and new studies appear to strengthen that 
               conclusion.
                    Researchers now theorize that a ubiquitous mammalian 
               protein called prion protein can, rarely, refold itself into 
               a toxic form that then spreads conversion of more healthy 
               protein in a runaway process. Some mutant forms of the 
               protein are more likely to convert spontaneously than others, 
               accounting for the rare sporadic cases of TSE in humans. TSEs 
               are both inherited and transmittable, and unlike any other 
               known diseases, the pathogen lacks DNA and RNA.
                    A test for TSEs in humans and in a few animals was 
               announced in September 1996, but so far it seems to perform 
               well only when clear symptoms of illness have already 
               developed.