3 biologists win 2020 Nobel Prize for Hepatitis C discovery

Biologists Harvey Alter, Michael Houghton and Charles Rice have jointly won the 2020 Nobel Prize in Physiology or Medicine for discovering the Hepatitis C virus.

Announcing this year’s winners at the Swiss Karolinska Institute, the Nobel Committee said the three made a significant contribution to the world's fight to control and eradicate Hepatitis C, which is carried and spread through the blood.

"The 2020 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," the committee said in a statement.

The three scientists made important discoveries that led to the identification of the novel Hepatitis C virus.

Before their crucial discoveries, other researchers had identified Hepatitis A and B viruses in the 1940s.

The Nobel Prize honors scientific research, writing and actions that the Nobel Foundation sees as important service to humanity.

For winners, this prize comes with a diploma, a medal and a cash award. Each year, the Nobel Foundation decides on the cash prize awarded to each laureate.

The cash prize is 8 million Swiss Francs (SEK), approximately $1.1 million or Sh119 million.

Sometimes the prize goes to a single individual or is split between two or among three recipients.

Early stages

Hepatitis or liver inflammation is mainly caused by viral infections. Other significant causes include autoimmune disease, environmental toxins and over consumption of alcohol abuse, and autoimmune disease.

In the 1960’s, Prof Baruch Blumberg found out that one form of blood-borne hepatitis was caused by a virus that became known as Hepatitis B virus

His discovery opened doors to the development of diagnostic tests and an effective vaccine.

For his groundbreaking discovery, Prof Blumberg won the Nobel Prize in Physiology or Medicine in 1976

There are two common types of infectious hepatitis. Hepatitis A is transmitted by polluted water or food and does not adversely affect the patient while Hepatitis B is transmitted through blood and bodily fluids and can lead to a chronic condition as it results in the patient developing cirrhosis and liver cancer.

Type B can silently live in the patient's body for years before they develop serious complications.

The other form of Hepatitis is caused by Hepatitis B or Hepatitis C viruses. It is usually a chronic disease that may go on to cause cirrhosis and hepatocellular carcinoma, which are liver diseases.

Blood-based hepatitis kills more than a million people every year across the globe, and is regarded as a global health concern.

Despite previous knowledge of Hepatitis A and B, the cause of the majority of blood-borne hepatitis cases had remained a mystery to scientists.

"The discovery of Hepatitis C virus revealed the cause of the remaining cases of chronic hepatitis and made possible blood tests and new medicines that have saved millions of lives," the statement said.

Alter’s work

At that time of Blumberg's discovery, Prof Alter was based at the US National Institutes of Health.

His work focused on hepatitis in patients who had received blood transfusions.

Although blood tests for the newly-discovered Hepatitis B virus had significantly reduced the number of cases of hepatitis attributed to blood transfusions, Prof Alter and his colleagues still managed to show that the disease was still present in a large number of blood samples.

Since the tests for Hepatitis A virus infection were also developed around this time, scientists realised that Hepatitis A was not the cause of the unexplained blood-borne hepatitis cases.

Prof Alter and his colleagues were able to show that blood from these hepatitis patients could transmit the disease to chimpanzees, which are the only species besides humans that can be infected by the virus.

"Subsequent studies also demonstrated that the unknown infectious agent had the characteristics of a virus. Alter’s methodical investigations had in this way defined a new, distinct form of chronic viral hepatitis. The mysterious illness became known as “non-A, non-B” hepatitis," said the statement.

In a bid to identify the virus, scientists used the conventional methods for the process, but were unable to make headway for 10 years.

Houghton’s contribution

In 1989, Prof Houghton, a researcher at the pharmaceutical firm Chiron, led his team that included Qui-Lim Choo, George Kuo and Daniel Bradley, in isolating DNA samples from nucleic acids found in the blood of an infected chimpanzee.

Although most of these fragments came from the genome of the chimpanzee itself, the scientists predicted that some would come from the unknown virus.

The investigators then used serum drawn from hepatitis patients' blood to identify cloned DNA fragments that produced viral proteins and helped them identify antibodies against the virus.

After a thorough search, scientists identified one positive clone derived from a novel RNA virus belonging to the Flavivirus family.

Researchers named it the Hepatitis C virus.

This was because the presence of antibodies in chronic hepatitis patients strongly implicated this virus as the missing agent.

In summary, studies on transfusion-related hepatitis by Prof Harvey Alter showed that an unknown virus was a common cause of chronic hepatitis.

Prof Houghton then used a unique method to isolate the genome of the new virus that was named Hepatitis C virus.

Rice’s evidence

Prof Rice provided the final evidence showing that Hepatitis C virus could cause hepatitis on its own.

The discovery of Hepatitis C virus was important but it was not yet known whether the virus alone could cause hepatitis.

Working with other scientists, Prof Rice, of the Washington University in St Louis, identified a region located in the end of the Hepatitis C virus genome which his team believed to be the one responsible for the reproduction of the virus

Through genetic engineering, Prof Rice produced an RNA sample of Hepatitis C virus that included the newly defined region of the viral genome that could replicate the virus.

When the team injected the RNA into the liver of chimpanzees, the virus was detected in the blood, along with the symptoms and physical changes similar seen in infected humans.

The process proved that the Hepatitis C virus alone could cause the unexplained cases of transfusion-mediated hepatitis.

The discovery has enabled the development of highly sensitive blood tests for the virus.

"These tests have eliminated post-transfusion hepatitis in many parts of the world, greatly improving global health. Their discovery also allowed the rapid development of antiviral drugs directed at hepatitis C. For the first time in history, the disease can now be cured, raising hopes of eradicating Hepatitis C virus from the world population," said the Karolinska Institutet.

"This breakthrough also enabled the development of antiviral drugs that can cure the disease. Hepatitis C remains a major global health concern, but the opportunity now exists to eliminate the disease.”

To achieve this goal, international efforts for availing cheap and effective blood testing as well as making antiviral drugs available across the globe will be required.