July 26, 20232:33 PM ET By Bec Roldan
How do viruses do their job of infecting humans? Some of them are experts at evading the immune system so that it won't knock them out.
Take hepatitis C, a sneaky and potentially deadly viral infection of the liver that is transmitted by contact with human blood – for example, through needles, sex and childbirth.
Scientists have known for a long time that hep C can hide from our immune system. While the immune system might attack the invading virus at first, leading to mild symptoms like fever or fatigue, the virus eventually hides so the immune system gives up the chase. Which is why most patients with hep C never show symptoms.
That gives hep C plenty of time to replicate and spread throughout healthy liver cells, leading to a chronic case of hepatitis C.
"We have this constant battle going on with these viruses," says Jeppe Vinther, a professor of biology at the University of Copenhagen who studies hepatitis C. "We are trying to defeat them and they are trying to avoid being detected and defeated."
But scientists didn't know how hep C pulled off its hiding trick. A new study led by Vinther and published in the journal Nature offers an explanation.
The cap is the keySo how does hep C do it? The virus uses standard villain fare to evade detection: a mask.
Hepatitis C is an RNA virus – one of several viruses that rely on their RNA instead of their DNA to carry information needed to take over the body's healthy cells. Other RNA viruses include measles, mumps, influenza and SARS-CoV-2.
RNA molecules in our body have a protecting group of DNA building blocks at their end known as a cap. These caps have various functions, including sending a message to our immune system: Leave us alone! Do not destroy us!
Since RNA viruses lack caps, once they invade our body, says Vinther, the cell control alarm bells go off and the immune system is activated to kill the foreign RNA.
This new study shows that when your body is infected with hep C, the virus attracts a cap for its RNA – like the protective cap on the body's own RNA. The researchers don't know exactly how the hep C virus does this — one of the many mysteries about viruses.
TO CONTINUE READING: https://www.npr.org/sections/goatsandsoda/2023/07/26/1187040969/hep-c-has-a-secret-strategy-to-evade-the-immune-system-and-now-we-know-what-it-i