1In the early 1950s, Kuru disease was prevalent in the virgin forest of the western highlands of New Guinea, a South Pacific island country. Gajdusek is determined to conquer this disease. At first, he thought that the pathogen was microorganism, but no microorganism was found from the patient. Later, according to the virus tracing, there was still no result. As a result, Gajdusek gave up the idea of finding the cause in microorganisms or viruses, and turned his attention to people's daily food. He made a thorough examination of the diet of the local ethnic groups and found no cause of disease. He also suspected that metal was the cause of the disease, and checked the composition of local drinking water and soil, but still could not find out the reason. In order to find out the cause of this strange disease, Gajdusek and the Fulu people live together every day and observe it carefully, but in the end they deny the idea that the pathogen exists in daily life.

A respected elder in the village died of kuru disease. In order to remember the kindness of the elder, family members and relatives and friends gathered all night, cut off the head of the elder, cut the brain into pieces and distributed it to the people attending the ceremony. They put the brain pieces in their mouths and ate them. Gajdusek has been watching carefully beside, come forward to get a piece of brain. He took the brain back and ground it, carefully detecting whether there were microorganisms or viruses on it, but still found nothing. He transplanted the protein particles extracted from this brain into the brain of the orangutan. However, the orangutan did not have the symptoms he expected.

However, after a while, the orangutan became ill. He selected a small piece of the brain of the deceased with Kuru disease, re-grinded it, filtered it with a filter that microorganisms could not pass through, and removed other substances, leaving only the protein part. Finally, the protein particles cut into many small pieces were transplanted into the brain of healthy orangutans. As a result, this orangutan got sick again. He also extracted the brain of this orangutan, processed it according to the above process and transplanted it to a healthy orangutan. This orangutan also showed symptoms of kuru disease. In further experiments, he found that if the protein particle was treated by proteolytic enzyme and then transplanted, the orangutan would not get sick. From these experimental results, Gajdusek came to the conclusion that the pathogen of Kulu disease is a chronic virus that invades the brain and nervous system. It takes brain tissue as the main host and can lurk for a long time. It turned out that the pathogen was a prion.