- Several Hepatitis C drugs have been found to inhibit a crucial protein enzyme in the novel coronavirus SARS-CoV-2. The experiments were led by researchers at the US Department of Energy’s Oak Ridge National Laboratory. The results are published in the journal structure.
- Once it has entered the human cell using its spike protein, the coronavirus uses an enzyme called the main protease to replicate. The coronavirus expresses long chains of compounds, which must be cut by the main protease to become functional proteins. Inhibiting the functioning of the main protease, therefore, is vital to stopping the virus from spreading in patients with Covid-19.
- The new study is part of efforts to quickly develop treatments for Covid-19 by repurposing existing drugs for other viral diseases.
- Researchers looked at several well-known drug molecules for potential repurposing efforts. These included three hepatitis C protease inhibitors: telaprevir, narlaprevir and boceprevir.
- The team performed room-temperature X-ray measurements to build a three-dimensional map of chemical bonds formed between the protease and the drug molecules. The experiments yielded promising results for certain hepatitis C drugs in their ability to bind and inhibit the main protease — particularly boceprevir and narlaprevir.
- The study used a technique called in vitro enzyme kinetics. This enables researchers to study the protease and the inhibitor in a test tube to measure the inhibitor’s binding affinity with the protease. The higher the binding affinity, the more effective the inhibitor is at blocking the protease from functioning.
- The study also sheds light on a peculiar behaviour of the protease’s ability to change or adapt its shape according to the size and structure of the inhibitor molecule it binds to. Pockets within the protease where a drug molecule would attach are highly flexible, and can either open or close to an extent.
Hepatitis C Virus
- Hepatitis C virus (HCV) is a bloodborne virus and causes liver diseases. It refers to an inflammatory condition of the liver.
- The novel virus caused several deaths in the 1960s and 1970s — but remained unknown until its discovery in the late 1980s.
Other Hepatitis Viruses
- Before the discovery of the Hepatitis C virus, two other viruses were known to cause hepatitis in patients.
- The Hepatitis A virus was known to spread mainly through contaminated food and water and caused a relatively milder form of liver inflammation.
- Hepatitis B, discovered in the 1960s, was known to transmit mainly through infected blood and caused a more serious form of the disease.
- Incidentally, the discovery of the Hepatitis B virus too was rewarded with a Nobel Prize in Medicine, given to Baruch Blumberg in 1976. There are vaccines available for this disease now.