This year’s Nobel Prize is awarded to three scientists who have made a decisive contribution to the fight against blood-borne hepatitis, a major global health problem that causes cirrhosis and liver cancer in people around the world.
Harvey J. Alter, Michael Houghton, and Charles M. Rice made fundamental discoveries that led to the identification of a new virus, the hepatitis C virus. Prior to their work, the discovery of the hepatitis A and B viruses had been a critical step forward, but the majority of blood-borne hepatitis cases remained unexplained. The discovery of the hepatitis C virus revealed the cause of the remaining cases of chronic hepatitis and enabled blood tests and new drugs that have saved millions of lives.
Hepatitis: a global threat to human health
Inflammation of the liver, or hepatitis, is caused primarily by viral infections, although alcohol abuse, environmental toxins, and autoimmune diseases are also major causes.
Specifically, hepatitis C is an infectious disease of the liver, the causative agent of which is known as the hepatitis C virus (HCV). Approximately 71 million people worldwide have a chronic HCV infection, making hepatitis C a major source of chronic liver disease.
The burden of HCV infection varies by country and population. In Egypt, for example, approximately 10-15% of people between the ages of 15 and 59 are chronically infected with HCV. In Sweden, by contrast, the prevalence is around 0.5%.
The achievements of the awardees
For the first time in history, the hepatitis C virus can now be cured. The 2020 Medicine Awards discoveries revealed the cause of the remaining cases of chronic hepatitis and made possible blood tests and new drugs that have saved millions of lives.
Harvey J. Alter, Michael Houghton, and Charles M. Rice made seminal discoveries that led to the identification of the new virus, the hepatitis C virus. Methodical studies of transfusion-associated hepatitis conducted by the 2020 Harvey J. Alter showed that an unknown virus was a common cause of chronic hepatitis.
Michael Houghton used an unproven strategy to isolate the genome of the new virus called the hepatitis C virus. Charles M. Rice, for his part, provided the final evidence showing that the hepatitis C virus alone can cause hepatitis.
Identification of the hepatitis C virus, a priority
All the traditional techniques for searching for viruses were put into practice, but despite this, the virus eluded isolation for more than a decade. Michael Houghton, who worked for the pharmaceutical company Chiron, undertook the hard work necessary to isolate the genetic sequence of the virus. Houghton and his collaborators created a collection of DNA fragments from nucleic acids found in the blood of an infected chimpanzee. Most of these fragments come from the chimpanzee’s own genome, but the researchers predicted that some would be derived from the unknown virus.
Assuming that antibodies to the virus would be present in blood drawn from hepatitis patients, the researchers used patient sera to identify cloned viral DNA fragments that encode viral proteins. After an exhaustive search, a positive clone was found. Later work showed that this clone was derived from a new RNA virus belonging to the Flavivirus family, and was named hepatitis C virus. The presence of antibodies in patients with chronic hepatitis strongly implicated this virus as the missing agent.
