Presentation Speech by Professor Erling Norrby of the Karolinska Medico-Chirurgical Institute

Translation from the Swedish text

Your Majesties, Your Royal Highnesses, Ladies and Gentlemen,

An occasional encounter with infectious agents is part of our daily life. The smallest among these infectious agents are called viruses. In spite of their small size viruses may cause many different types of infections. When the virus of common cold comes into contact with our respiratory tract, certain well known symptoms appear after a few days. However, the body can defend itself against the attack by the virus. Under normal conditions we recover after a few days of illness.

Occasionally infections occur which take a completely different course. The Nobel prize winners of this year have described mechanisms involved in such infections. They have studied diseases of two different kinds.

Baruch Blumberg investigated, in the beginning of 1960, the inheritance of specific blood proteins. In connection with this, he discovered a new protein. Eventually it was shown that Blumberg, like the princes of Serendip, had found something completely different from the types of substances he was looking for. The protein he had discovered was not a part of normal body constituents but instead a virus causing jaundice.

It has been known since 1940 that there are two different forms of virus-induced jaundice. One form of the disease is transmitted as an intestinal infection whereas the other form is propagated primarily by blood transmission. The virus discovered by Blumberg caused the latter form of the disease. After exposure to this virus, disease of the liver may appear after 3-4 months. Normally symptoms of the disease wane after a few weeks. However, in certain individuals the body lacks the capacity to eliminate the virus infection, which therefore persists throughout life. Such a persistent infection occurs in about one out of 1000 persons in an industrialized society and altogether in more than 100 million individuals around the world. Individuals who carry this kind of persistent infection represent the source of further virus transmission. Due to Blumberg’s discovery it is possible today to identify these individuals. Such a person, for example, should not become a blood donor. New possibilities for prevention of this type of jaundice have also become available. A vaccine is currently being tested.

Carleton Gajdusek studied in the end of 1950 a remarkable disease in a neolithic people living in the highlands of New Guinea. The disease, named kuru, involved a progressive destruction of the brain, which eventually resulted in death. Kuru lacks the regular signs of an infectious disease, e.g. fever and inflammation. In spite of this Gajdusek showed that the disease was caused by an infectious agent which in chimpanzees gave a disease identical with kuru in man. It took 1 1/2-3 years before the first symptoms appeared in infected animals. By this discovery it was made possible to clarify the origin of the disease kuru.

Amongst the people suffering from this infection about 3000 of 35,000 persons have died of the disease during a study period of 20 years. Transmission of the disease occurred in connection with a mourning ceremony at which dead relatives were cannibalized. This form of funeral ceremony ceased in 1959 and as a consequence kuru no longer occurs among children born after that year. However, cases of kuru still appear among adults. This implies that the infectious agent may remain in a dormant stage in the organism for many decades prior to appearance of disease.

However, the Karolinska Institute has not awarded the Nobel prize for this year to Gajdusek for his demonstration of the danger of cannibalism. The importance of his discovery of the origin of the kuru disease lies in the identification of a new class of human diseases caused by unique infectious agents. The fact that kuru, which lacks the classic signs of infections, still is caused by a contagious agent implies that we must investigate whether certain other diseases may arise in a similar way. An unusual form of presenile dementia of wide dissemination has also been shown by Gajdusek to be caused by an infectious agent.

Our normal defence mechanisms appear not to protect us against infectious agents of this kind. Furthermore, these infectious agents display a much greater resistance against destruction by e.g. boiling and irradiation than regular viruses. Thus, we are dealing with a completely different type of infectious agent the exact nature of which still remains to be demonstrated.

Baruch Blumberg and Carleton Gajdusek.

You have made discoveries giving us new views on mechanisms of infectious diseases. The impact of your conceptual reformulations is wide. New directions have been given for future research. On behalf of the Karolinska Institute, I wish to convey to you our warmest congratulations, and I now ask you to receive your Nobel prizes from the hands of His Majesty the King.