This year’s Nobel Prize for Medicine goes to three virus discoverers – in keeping with the corona pandemic. The award goes to the physicians Harvey Alter, Michael Houghton and Charles Rice for the discovery of the viral pathogen causing hepatitis C. This virus, which can be transmitted via blood and body fluids, causes the third form of hepatitis alongside A and B and is responsible for millions of diseases and deaths worldwide. Only the discovery of the pathogen made targeted blood tests and the development of a cure possible. “It is a groundbreaking milestone in the ongoing fight against viral diseases,” said the Nobel Prize Committee.
Viral hepatitis is one of the most common infectious diseases worldwide: According to the World Health Organization, more than 325 million people live with chronic hepatitis infection. 1.7 million people are infected with hepatitis C every year. The fatal thing about it: Hepatitis viruses cause liver inflammation and destroy liver tissue over time. This can lead to liver cirrhosis and liver cancer – and lead to death. Today medical professionals know five different viruses that can cause hepatitis. However, that was not the case for a long time. Until the 1960s, only two forms were known: the hepatitis A virus, which is transmitted via contaminated water or food, and the hepatitis B virus, which is transmitted via blood and other body fluids.
There must be a third pathogen …
But there was a large proportion of hepatitis illnesses that could not be traced back to either of these two known pathogens – this was also noted by Harvey Alter, who worked at the US National Institutes of Health in the 1960s. After tests for hepatitis A and B, there were still many cases of liver inflammation in the patient blood samples he examined, for which there was no explanation. Alter and his team decided to put it to the test: they took blood from these unexplained cases and passed it on to chimpanzees – these great apes, like us, can get hepatitis. And then the monkeys actually got sick. This made it clear that the blood must contain an as yet unknown pathogen. More detailed investigations – including through prior filtration of the administered samples – showed that it must be a virus.
The second step in the search for the pathogen was taken by the British Michael Houghton, who was then doing research at the University of Alberta in Canada. He first looked in the blood of the infected chimpanzees for pieces of DNA whose signature could have come from a virus. To do this, Houghton and his team isolated antibodies from the blood of infected hepatitis patients and allowed them to react with the isolated DNA fragments. There was a hit: the antibodies bound to one of the genetic material. More detailed analyzes showed that this piece of DNA was produced by the monkey’s cells, but that its “template” was the genetic make-up of an RNA virus. Accordingly, the pathogen we were looking for was a single-stranded RNA virus with positive polarity – such as the coronavirus SARS-CoV-2, the Zika virus, the TBE virus or the dengue virus. Houghton and his colleagues also narrowed down the pathogen as a member of the flaviviruses.
“Milestone in the fight against viruses”
Finally, the last step was taken by Charles Rice of Washington University St. Louis. Because even if it was now clear that there was apparently a third hepatitis virus, there was still no proof that this pathogen actually caused the liver inflammation and damage observed in the patients. To test this, Rice created a special variant of the new hepatitis C virus and injected it in pure form into the livers of chimpanzees. It was found that the animals then developed the same pathological changes in their liver tissue as the human patients with chronic hepatitis C. The same biomarkers were also found in the blood. This finally proved that the newly discovered hepatitis C virus must actually be the cause of the millions of previously unexplained hepatitis cases.
It was only with this discovery of the hepatitis C virus that it was possible to develop blood tests that have since prevented unwitting transmission during blood transfusions. In addition, since then, antiviral drugs have been developed that contain the virus disease and prevent severe liver damage. “The discovery of the hepatitis C virus by the three Nobel Prize winners is a milestone in the ongoing fight against viral diseases,” stated the Nobel Prize Committee. “It can now cure hepatitis C and that raises hope of eradicating this virus entirely from the population.”
Source: Nobelprize.org