Professor Eui-Cheol Shin from KAIST Graduate School of Medical Sciences and Engineering and his team of researchers have discovered the molecular mechanism behind why the hepatitis C virus does not cause an immune reaction inside the body upon infection. Hepatitis affects 1% to 2% of the Korean population. However, because it is rarely detected by the immune system, it develops into a full disease, such as liver inflammation and even liver cancer.

When a foreign molecule such as a virus enters the human body, an immune response is initiated. The first step of the immune response involves the formation of complexes, usually with antibodies, on the surface of the viruses. This happens after the foreign object enters a cell, inciting the cell to activate a protein called interferon. This allows the T cells to recognize the infected cell, attack it, and remove it from the body. However, hepatitis C viruses somehow avoided this marking by the immune system and escaped detection.

Professor Shin and his team found that the hepatitis C virus inhibits the formation of a protein critical to the first step of immune response. More specifically, the hepatitis C virus was found to activate a protein called protein kinase R (PKR) to deactivate the immune responses and inhibit the expression of interferon. So the research team theorized that they could force the hepatitis C virus to be recognized by the immune system by controlling the PKR concentrations in cells. Their findings supported this theory and were published in the May issue of Journal of Gastroenterology.

Hepatitis A and B can both be vaccinated against, but hepatitis C cannot, and the only method of prevention is simply avoiding contact with the virus, which is not fail-proof. “While there are many new drugs that treat hepatitis C, there still are no vaccines available for the disease,” said Professor Shin, “Our findings will help with the discovery of a vaccine.”

The first author of this study, Doctor Won Suk Kang, received his Doctor of Medicine degree at Yonsei University, and is currently studying for a degree from the KAIST Graduate School of Medical Sciences and Engineering.