Viral hepatitis is a major public health problem throughout the world affecting several hundreds of millions of people. Viral hepatitis is a cause of considerable morbidity and mortality in the human population, from both acute infection and chronic sequelae which include, with hepatitis B and hepatitis C infection, chronic active hepatitis, cirrhosis and primary liver cancer.

The hepatitis viruses include a range of unrelated and often unusual human pathogens:

	•	Hepatitis A virus (HAV): a small unenveloped symmetrical RNA virus, which shares many of the characteristics of the picornavirus family. This virus has been classified in the hepatovirus genus, and is the cause of infectious or epidemic hepatitis transmitted by the faecal–oral route.
	•	Hepatitis B virus (HBV): a member of the hepadnavirus group of double-stranded DNA viruses which replicate by reverse transcription. Hepatitis B virus is endemic in the …