Epstein consoled Karumanchi by saying that he had fulfilled "Koch's postulates"-a reference to the Nobel laureate Robert Koch, who argued that the cause of a disease could be established by injecting animals with bacteria from sick patients.

They injected animals with two signaling proteins, known as cytokines, that are known to make bone marrow stem cells proliferate and rush out into the bloodstream.

Laboratory tests confirmed that the disease could be transmitted like scrapie by injecting healthy animals with ground-up brain tissue from diseased mink.

Previously, antibodies had been produced through a laborious and imprecise process, injecting animals like goats with antigens and then extracting antibodies of less than optimum purity from their blood.

But an application now before the Food and Drug Administration raises the issue of whether injecting even individual animals may interfere with human medical treatments.

The prion proponents, though they have found a protein that they say is a prion, have been unable to cause a disease when they inject animals with pure prion proteins.

He and his team inject animals with blue fluid and make them invisible.

When scientists inject animals with angiotensin, the animals have heart attacks and strokes.

Dr. Janeway said that about a year ago, immunologists noticed that if they injected animals with superantigens from bacteria, the animals' T4 cells would divide, but then many of the T4 cells would disappear.