THE normally staid Nobel Assembly plunged headlong into controversy this week
when it awarded its 1997 prize for medicine to Stanley Prusiner, the biochemist
who proposed that proteins, like viruses and bacteria, can cause infectious
disease.
Prusiner鈥檚 theory is now the leading explanation for the mysterious group of
degenerative brain disorders that includes Creutzfeldt-Jakob disease, scrapie
and BSE. But with a sizable minority of researchers still believing that a more
conventional infectious agent is to blame, reactions to the award have been
mixed.
In the early 1980s, Prusiner and his colleagues at the University of
California at San Francisco tried to purify the protein that builds up in the
brains of animals with scrapie. Even when their isolate seemed to contain only
protein, it still caused disease if injected into rodents. Prusiner proposed
that the agent, which he called a prion, was a protein that could adopt more
than one shape, one of which causes disease. The misshapen version, he
suggested, could force the normal version into the diseased shape. Over time,
this insidious conversion would cause the misshapen protein to build up, slowly
destroying the brain.
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Prusiner went on to clone the gene for the prion protein, called PrP,
and showed that its mutation could lead to neurological disease. Meanwhile,
others found that mice lacking the PrP gene were immune to injections
of scrapie-infected brain tissue. The PrP protein appeared to be required for
disease to set in.
Prusiner鈥檚 doggedness in pursuing his theory in the face of widespread
scepticism is not disputed. 鈥淧rusiner is a true pioneer and an iconoclast,鈥� says
Charles Weissmann of the University of Zurich. 鈥淗e has done great science and
pushed ahead the field,鈥� agrees Allen Roses, chief of neurology at Duke
University Medical Center in Durham, North Carolina.
But sceptics point out that copper-bottomed proof of Prusiner鈥檚 theory is
still lacking. Protein purified from the brains of diseased animals might
contain an elusive virus, they argue. The acid test would be to show that prions
synthesised in the laboratory cause disease. But nobody has yet been able to
make enough of the material to run the experiment.
Even Prusiner now argues that some other protein, which he dubs 鈥減rotein X鈥�,
must be required for the prion conversion to take place. His critics suggest
that protein X is actually virus X.
鈥淚鈥檝e always said that if the prion hypothesis were proven, then he would
deserve the Nobel prize,鈥� says Hugh Fraser, formerly director of the
Neuropathogenesis Unit at the Institute for Animal Health in Edinburgh, and a
long-time opponent of Prusiner. 鈥淏ut all that the genetics proves is the need
for a protein.鈥�
Neurologist Laura Manuelidis of Yale University, another prominent sceptic,
is more barbed: 鈥淚 congratulate him on winning the Nobel prize. It鈥檚 a great
honour. But the real prize is scientific truth.鈥�
Even some of those who think Prusiner may in the end be proved right believe
the prize is premature. One researcher, who wishes to remain anonymous, calls
the award 鈥渉igh-level approval of propaganda as science鈥�. He fears that the
publicity it generates could interfere with further research to get to the
bottom of the mystery. 鈥淧eople may just waltz off and assume it鈥檚 a done
诲别补濒.鈥�
Breaking his usual rule of not speaking to the press, Prusiner earlier this
week acknowledged the continuing controversy surrounding his work. 鈥淎wards do
not vindicate a piece of science,鈥� he told the small band of reporters who
tracked him down to a meeting near Washington DC. 鈥淥nly data does that.鈥�
While many researchers say they are still waiting for those data, some
applaud the Nobel Assembly鈥檚 courage in not shying away from controversy. 鈥淭hey
do it for the peace prize, they should do it for this,鈥� says Roses.