2020 Nobel Prize in Physiology or Medicine
Reason for Award
for the discovery of the Hepatitis C virus
Laureates
United States of America
United Kingdom of Great Britain and Northern Ireland
United States of America
Explanation
Inside our bodies we have the liver, a factory that sorts nutrients and removes poisons. The Hepatitis C virus is a tiny enemy that quietly slips into this factory and slowly damages it. In 2020 three scientists—Harvey J. Alter, Michael Houghton and Charles M. Rice—won the Nobel Prize because they were the first to find this virus. Thanks to their discovery, hospitals can now test donated blood and make sure it is safe. New medicines that knock out the virus have also been created, saving many lives. Finding the cause of a disease is the very first step toward protecting everyone’s health.
Related Keywords
Hepatitis C virus
A positive-sense single-stranded RNA virus (~50 nm) classified in the genus Hepacivirus, family Flaviviridae. Transmission is mainly parenteral, with acute infection often silent but frequently progressing to chronicity. Long-term infection can culminate in cirrhosis and hepatocellular carcinoma. Eight major genotypes are proposed, differing in drug susceptibility and geographic prevalence. Establishment of full in-vitro culture systems accelerated life-cycle studies and antiviral discovery.
RNA virus
A collective term for viruses whose genomes are RNA. Their RNA-dependent RNA polymerases lack efficient proofreading, leading to high mutation rates. HCV exemplifies this, and its genetic diversity drives immune evasion and drug resistance. Accumulated mutations form quasispecies that facilitate host adaptation. Scientists exploit this error-prone replication to design antivirals; thus RNA virology connects public health with evolutionary biology.
Blood screening
A set of tests to ensure transfusion or transplant materials are free from pathogens. Before HCV discovery, only HBV screening was routine, leaving 80 % of post-transfusion hepatitis cases unchecked. Introduction of anti-HCV antibody assays and nucleic-acid testing (NAT) has virtually eliminated transfusion-related HCV in high-income countries. High-sensitivity NAT shortens the window period, boosting safety. Implementing comparable screening in low- and middle-income regions remains a challenge.
Direct-acting antivirals (DAAs)
A class of drugs that directly inhibit viral proteins or enzymes; for HCV the main targets are NS3/4A, NS5A and NS5B. First-generation protease inhibitors faced rapid resistance when used alone. Current standard therapy combines DAAs with different mechanisms, achieving sustained virologic response (functional cure) rates above 95 % after about 12 weeks. They have mild side-effects and removed the need for interferon, a major breakthrough. Wider access to generic DAAs is essential for global hepatitis elimination.
Cirrhosis
A condition in which chronic liver injury leads to repeated cycles of cell death, regeneration and fibrosis, resulting in a hardened, nodular liver architecture. Complications include portal hypertension, ascites and esophageal variceal bleeding. In industrialized nations HCV was the second leading cause of cirrhosis after alcohol. Viral clearance with DAAs slows fibrosis progression and partial reversal has been documented. Nonetheless, advanced cirrhosis leaves residual hepatocellular carcinoma risk, necessitating ongoing surveillance.
Hepatocellular carcinoma
A primary malignant tumor of the liver; major risk factors include chronic infections with HCV or HBV and alcohol-induced liver disease. Persistent inflammation and fibrosis drive DNA damage and uncontrolled cell proliferation. HCV accounts for roughly 20 % of global HCC cases, notably prevalent in Japan, Egypt and Italy. Incidence is declining as DAAs spread, yet patients with established fibrosis remain at risk. Regular ultrasound and AFP monitoring are advised for early detection.
Flaviviridae family
A family of enveloped positive-sense RNA viruses that also includes Dengue, Zika and Yellow fever viruses. HCV belongs to the genus Hepacivirus and shares genome organization and polyprotein processing with other flaviviruses. Conserved enzymatic domains such as NS3 protease and NS5 polymerase are attractive drug targets. Comparative virology within Flaviviridae enhances understanding of both vector-borne and blood-borne diseases. Phylogenetic analyses are used to study viral evolution and host adaptation.
Interferon therapy
An immune-stimulating drug once standard for hepatitis C, administered by weekly subcutaneous injections for six months or longer. Side-effects such as flu-like symptoms, depression and cytopenia led to high discontinuation rates. Sustained virologic response reached only 40–50 %, particularly low for genotype 1 infections. With the advent of DAAs it is now relegated to second-line or adjunct therapy. Nonetheless, interferon’s immunomodulatory properties are being revisited in certain refractory cases and other viral diseases.