How hepatitis C virus avoids immune system: Scientists solve age-old puzzle

The result of the research may have an impact on how viral diseases in general are tracked and treated. Photo: IANS

London: An old riddle about how the Hepatitis C virus avoids the human body's immune defences has been solved by a team of Danish researchers. The result may have an impact on how we track and treat viral diseases in general.

An estimated 50 million people worldwide are infected with chronic hepatitis C. The hepatitis C virus can cause inflammation and scarring of the liver, and in the worst case, liver cancer.

Hepatitis C was discovered in 1989 and is one of the most studied viruses on the planet. Yet for decades, how it manages to evade the human immune system and spread through the body has been a riddle.

Researchers at the University of Copenhagen and Hvidovre Hospital found that the virus just puts on a "mask", helping it to remain hidden while making copies of itself to infect new cells. The mask cloaks the virus in the form of a molecule already in our cells.

Disguised by the molecule, our immune systems confuse the virus with something harmless that needn't be reacted to. "How the Hepatitis C virus manages to hide in our liver cells without being detected by the immune system has always been a bit of a mystery. Our revelation of the virus' masking strategy is important, as it could pave the way for new ways of treating viral infections. And it is likely that other types of viruses use the same trick," said Jeppe Vinther, Associate Professor of the university’s Department of Biology.

The mask used by the hepatitis virus to hide in our cells is called FAD, a molecule composed of Vitamin B2 and the energy-carrying molecule ATP. FAD is vital for our cells to convert energy. The FAD molecule's importance and familiarity with our cells make it ideal camouflage for a malicious virus.

For several years, the research team had a good idea that FAD was helping the virus hide in infected cells, but they lacked a clear way to prove it. To solve the challenge, they turned to Arabidopsis, a well-known experimental plant among researchers. "We were getting desperate to find a way to prove our hypothesis, which is when we purified an enzyme from the Arabidopsis plant that can split the FAD molecule in two," explained Anna Sherwood from the Department of Biology. Using the enzyme, the researchers were able to split the FAD and prove that the hepatitis C virus used it as a mask.

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