More than 250 million people world-wide are chronically infected with the hepatitis B virus (HBV). This virus is transmitted by the blood and other body fluids. Hepatitis B is a major risk factor for the development of liver cirrhosis and liver cancer. Researchers of the Paul-Ehrlich-Institut, Federal Institute for Vaccines and Biomedicines in co-operation with other research groups have investigated how HBV evades the defences of the immune system. Viruses reports in the results in its online edition of 29 May 2020.