The Hindu Explains | How the black hole came of age, genetic scissors and rewriting the code of life, and the seminal discovery of the Hepatitis C virus

The Hindu Explains | How did the 2020 Medicine Nobel winners identify Hepatitis C infectious agent?

This combination of photos shows, from left, Harvey J. Alter, Charles M. Rice, and Michael Houghton who jointly won the Nobel Prize for medicine on October 5, 2020, for their discovery of the hepatitis C virus.   | Photo Credit: AP

The story so far: This year’s Nobel Prize in Physiology or Medicine has been awarded to Harvey J. Alter, Michael Houghton and Charles M. Rice for their discovery of the Hepatitis C virus. The Nobel announcement said the Prize had been given 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”.

Why is the finding crucial?

Hepatitis (Greek for liver inflammation) is a disease characterised by ‘poor appetite, vomiting, fatigue and jaundice, including yellow discoloration of the skin and eyes. Chronic hepatitis leads to liver damage, which may progress to cirrhosis and liver cancer’. The Nobel release elaborately explains that “viral infection is the leading cause of hepatitis, with some forms persisting without symptoms for many years before life-threatening complications develop”.

Watch | All about the 2020 Nobel Prize in Physiology or Medicine
 

It is said the first description of hepatitis was recorded around 400 BC by the Greek physician Hippocrates. “Infectious hepatitis may be caused by five different types of RNA or DNA viruses that are the most common cause of hepatitis worldwide,” notes the Nobel communique.

Hepatitis A spreads through contaminated food and water, and through direct contact with an infected person, including some sexual activity. Until the 1960s, exposure to blood from infected individuals was a major health hazard, with up to 30% risk of contracting chronic hepatitis following surgery or multiple blood transfusions. It was Nobel laureate Baruch Blumberg, a geneticist working at the United States’ National Institutes of Health (NIH) in Bethesda, who discovered the Hepatitis B virus (HBV) and made way for almost everything that followed in the hepatic virology field. This year’s laureate, Harvey Alter, worked with Blumberg in the lab during this phase. But even the identification and classification of the HBV, and the eventual elimination of HBV-contaminated blood through testing, only partially reduced the risk of getting hepatitis from blood. Clearly, the HBV was only a part of the riddle. Efforts were renewed to identify the missing pieces.

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It was also imperative that efforts be channelled in this direction as the different types of viral hepatitis contribute substantially to the global burden of hepatic diseases. According to the WHO Global Hepatitis Report, 2017, “Viral hepatitis caused 1.34 million deaths in 2015, a number comparable to deaths caused by tuberculosis, and higher than those caused by the HIV.” However, the number of deaths due to viral hepatitis is increasing over time, while mortality caused by tuberculosis and HIV is declining.

“Most viral hepatitis deaths in 2015 were due to chronic liver disease (720,000 deaths due to cirrhosis) and primary liver cancer (470,000 deaths due to hepatocellular carcinoma). Globally, in 2015, an estimated 257 million people were living with chronic HBV infection, and 71 million people with chronic HCV [Hepatitis C virus] infection … The epidemic caused by the HCV affects all regions, with major differences between and within countries. The WHO Eastern Mediterranean Region and the European Region have the highest-reported prevalence of HCV,” the report states.

 

How was the unknown factor traced?

Back at the lab, a working name was assigned to this still unknown causative factor, “non-A, non-B hepatitis” (NANBH). As the Nobel backgrounder explained, it was clear that the agent causing NANBH was responsible for an alarming number of post-transfusion hepatitis cases, and the situation was frightening, because most infected carriers showed no clinical symptoms.

The work of Dr. Alter and Dr. Houghton established a critical link between the NANBH and the HCV infection. Thereafter, the work of Charles Rice provided conclusive evidence that HCV alone could cause transfusion-mediated hepatitis, persist for a long time, and stimulate a specific antibody response — all features of the human infection.

Why is this award important?

The Nobel Assembly at Karolinska Institutet lauded the discovery of the Hepatitis C virus as a “landmark achievement in the ongoing battle against viral diseases”. The significance of choosing the work done by virologists and geneticists, at a time when others are sweating it out trying to decode the SARS-CoV-2 virus, cannot be missed. The Nobel’s recognition of pioneering work in this field is likely to be a boost to researchers whose battle with the COVID-19 virus has probably been as challenging as the decoding of the causative factors for hepatitis.

Editorial | Vanquishing viruses

Interestingly, Science, an academic journal, notes that till 2015, 106 Nobel prizes in Physiology or Medicine had been awarded to 210 laureates, and only 33 of these prizes were related to the realm of infectious diseases, clinical microbiology, and immunology.

What more needs to be done in the field?

Once the puzzle was cracked, screening methods were developed that have now dramatically reduced the risk of acquiring hepatitis from contaminated blood. Effective antiviral drugs have also become available, the Nobel acknwoledgement states.

In 2016, the World Health Assembly endorsed the Global Health Sector Strategy (GHSS) on viral hepatitis 2016–2021, calling for the elimination of viral hepatitis as a public health threat by 2030. Ensuring access to affordable testing and to viral therapeutics that will improve the quality of life and reduce deaths due to hepatitis should be the priority of governments, the WHO Global Hepatitis Report advises.

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